Younger patients are at increased risk for graft rupture and contralateral injury after anterior cruciate ligament reconstruction

External validation of the Norwegian anterior cruciate ligament reconstruction revision prediction model using patients from the STABILITY 1 Trial

PURPOSE

A machine learning-based anterior cruciate ligament (ACL) revision prediction model has been developed using Norwegian Knee Ligament Register (NKLR) data, but lacks external validation outside Scandinavia. This study aimed to assess the external validity of the NKLR model (https://swastvedt.shinyapps.io/calculator_rev/) using the STABILITY 1 randomized clinical trial (RCT) data set. The hypothesis was that model performance would be similar.

METHODS

The NKLR Cox Lasso model was selected for external validation owing to its superior performance in the original study. STABILITY 1 patients with all five predictors required by the Cox Lasso model were included. The STABILITY 1 RCT was a prospective study which randomized patients to receive either a hamstring tendon autograft (HT) alone or HT plus a lateral extra-articular tenodesis (LET). Since all patients in the STABILITY 1 trial received HT ± LET, three configurations were tested: 1: all patients coded as HT, 2: HT + LET group coded as bone-patellar tendon-bone (BPTB) autograft, 3: HT + LET group coded as unknown/other graft choice. Model performance was assessed via concordance and calibration.

RESULTS

In total, 591/618 (95.6%) STABILITY 1 patients were eligible for inclusion, with 39 undergoing revisions within 2 years (6.6%). Model performance was best when patients receiving HT + LET were coded as BPTB. Concordance was similar to the original NKLR prediction model for 1- and 2-year revision prediction (STABILITY: 0.71; NKLR: 0.68-0.69). Concordance 95% confidence interval (CI) ranged from 0.63 to 0.79. The model was well calibrated for 1-year prediction while the 2-year prediction demonstrated evidence of miscalibration.

CONCLUSION

When patients in STABILITY 1 who received HT + LET were coded as BPTB in the NKLR prediction model, concordance was similar to the index study. However, due to a wide 95% CI, the true performance of the prediction model with this Canadian and European cohort is unclear and a larger data set is required to definitively determine the external validity. Further, better calibration for 1-year predictions aligns with general prediction modelling challenges over longer periods. While not a large enough sample size to elicit the true accuracy and external validity of the prediction model when applied to North American patients, this analysis provides more support for the notion that HT plus LET performs similarly to BPTB reconstruction. In addition, despite the wide confidence interval, this study suggests optimism regarding the accuracy of the model when applied outside of Scandinavia.

LEVEL OF EVIDENCE

Level 3, cohort study.

Ten-year outcomes of anterior cruciate ligament reconstruction with hamstring tendon autograft and femoral fixation with a cortico-cancellous screw suspension device

PURPOSE

To evaluate the clinical and radiographic outcomes of anterior cruciate (ACL) reconstruction at minimum 10-year follow-up.

METHODS

Ninety-three patients who underwent primary unilateral ACL reconstruction with hamstring tendon autograft, transtibial technique and femoral cortico-cancellous screw suspension device (Athrax, Leader Medica s.r.l) between 2010 and 2012 were retrospectively reviewed. Mean follow-up was 136 months. Evaluation was performed using the International Knee Documentation Committee score (IKDC), Knee injury and Osteoarthritis Outcome Score (KOOS), Lysholm Knee Score and Tegner Activity Level Scale. Incidence of OA was determined by comparing standard anteroposterior and lateral weightbearing radiographs of the ACL-reconstructed and contralateral knee. Osteoarthritis severity was graded according to the Kellgren-Lawrence (KL) score.

RESULTS

Median Tegner activity level was 6 (5-7). Lysholm and IKDC scores were 100 (95-100) and 90 (86-95), respectively, KOOS was 98 (95-100). Of ACL-reconstructed knees, 41 (50%) had radiographic OA, of which 6 (7.3%) had severe OA (KL III). Of the contralateral healthy knees, 28 (34.1%) had radiographic evidence of OA. Of these 22 (26.8%) and 6 (7.3%) patients had, respectively, KL-I and KL-II. 11 patients (11.8%) underwent subsequent knee surgery: 5 (5.4%) revisions, 3 (3.2%) meniscal surgeries, 2 (2.2%) other surgeries, 1 (1.1%) contralateral ACL reconstruction.

CONCLUSIONS

The study demonstrates that ACL reconstruction with HT autograft and cortico-cancellous screw suspension device determines satisfying clinical results after 10 years of follow-up. From our cohort, a low rate of graft failure has been reported, even though almost 50% of patients present a knee OA greater or equal to grade II KL.

Estimation Failure Risk by 0.5-mm Differences in Autologous Hamstring Graft Diameter in Anterior Cruciate Ligament Reconstruction: A Meta-analysis

BACKGROUND

Because grafts are made in 0.5-mm increments clinically for anterior cruciate ligament (ACL) reconstruction, it is important to clarify how the failure rate decreases as the diameter increases. Moreover, it is important to know whether even a slight increase in the graft diameter decreases the risk of failure.

HYPOTHESIS

The risk of failure decreases significantly with each 0.5-mm increase in hamstring graft diameter.

STUDY DESIGN

Meta-analysis; Level of evidence, 4.

METHODS

The systematic review and meta-analysis have estimated the diameter-specific failure risk for each 0.5-mm increase in ACL reconstruction using autologous hamstring grafts. We searched for studies describing the relationship between graft diameter and failure rate published before December 1, 2021, in leading databases, such as PubMed, EMBASE, Cochrane Library, and Web of Science, according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. We included studies using single-bundle autologous hamstring grafts to investigate the relationship between failure rate and graft diameter of 0.5-mm intervals with >1-year follow-up. Then, we calculated the failure risk caused by 0.5-mm differences in autologous hamstring graft diameter. Assuming Poisson distribution for the statistical model, we employed an extended linear mixed-effects model in the meta-analyses.

RESULTS

Five studies containing 19,333 cases were eligible. The meta-analysis revealed that the estimated value of the coefficient of diameter in the Poisson model was -0.2357 with a 95% CI of -0.2743 to -0.1971 (P < .0001). With every 1.0-mm increase in diameter, the failure rate decreased by 0.79 (0.76-0.82) times. In contrast, the failure rate increased by 1.27 (1.22-1.32) times for each 1.0-mm decrease in diameter. The failure rate significantly decreased with each 0.5-mm increase in graft diameter in the range of <7.0 to >9.0 mm from 3.63% to 1.79%.

CONCLUSION

The risk of failure decreased correspondingly with each 0.5-mm increase in graft diameter in the range of <7.0 to >9.0 mm. Failure is multifactorial; however, increasing the graft diameter as much as possible to match each patient's anatomic space without overstuffing is an effective precaution that surgeons can take to reduce failures.

Differences in Short-Term Sport-Specific Functional Recovery After Primary ACL Reconstruction in the Adolescent Athlete

BACKGROUND

Although anterior cruciate ligament (ACL) injury rates have been studied extensively, it is unclear whether levels of functional and psychological readiness for return-to-sport after primary ACL reconstruction (ACLR) differ based on an athlete's primary sport.

HYPOTHESIS

Youth athletes in different primary sports will demonstrate differences in short-term functional recovery, as well as patient-reported psychological and functional recovery after primary ACLR.

STUDY DESIGN

Retrospective cohort study of consecutive patients treated for ACL injury in pediatric sports medicine clinics.

LEVEL OF EVIDENCE

Level 3.

METHODS

Patients included underwent primary ACLR between December 1, 2015 and December 31, 2019 and reported sports participation at the time of injury. Demographic data, sports participation, surgical data, functional testing scores (Y-Balance Test [YBT]), functional and psychological patient-reported outcome measures (PROMs), and timing of return-to-play clearance were reviewed. YBT scores were the primary metric for clearance. Four groups were studied: soccer, football, basketball, and other.

RESULTS

A total of 220 male and 223 female athletes were included; 65.28% of soccer players were female and 100% of football players were male (P < 0.01). At initial postoperative YBT testing (6-9 months), soccer players had higher operative (P < 0.01) and nonoperative (P < 0.01) leg composite scores when compared with basketball players. No significant differences were found between sports in functional or psychological PROMs at presurgical baseline or 6 months postoperatively. When compared with football, soccer players completed functional clearance in a shorter time from surgery (P = 0.02). Multivariate analysis showed level of competition as a significant independent variable for clearance in female athletes.

CONCLUSION

After primary ACLR, athletes, especially female athletes, demonstrated short-term sport-specific differences in YBT scores. Soccer players attained clearance sooner than football players. Level of competition influenced YBT composite scores in all athletes and time to clearance in female athletes.

CLINICAL RELEVANCE

Sport-specific differences in reinjury should be investigated to determine whether changes in return-to-play evaluation should be implemented.

Risk Factors for Ipsilateral Versus Contralateral Reinjury After ACL Reconstruction in Athletes: A Systematic Review and Meta-analysis

Background

Anterior cruciate ligament (ACL) reinjury after ACL reconstruction (ACLR) can occur on the ipsilateral or contralateral side. Limited evidence exists regarding the difference between the incidence of reinjury to either knee, which is important in developing interventions to prevent ACL reinjury.

Purpose

To compare the reinjury rate of the ACL on the ipsilateral side versus the contralateral side in athletes after ACLR and investigate the risk factors that may cause different reinjury rates between the sides.

Study Design

Systematic review; Level of evidence, 4.

Methods

A systematic review was performed based on the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. Studies that involved ACL reinjury in athletes after ACLR were reviewed. Considering several risk factors, including age and sex, a comparison of ACL reinjury incidence on the ipsilateral and contralateral sides was performed using a meta-analysis.

Results

Of the 17 selected studies, 3 were found to be at high risk of bias, and thus, 14 (n = 3424 participants) studies were included in the meta-analysis. In this athletic population, the contralateral ACL had a significantly higher rupture rate than the ipsilateral graft (risk ratio [RR], 1.41; P < .0001). Female athletes were found to have a greater risk of ACL reinjury on the contralateral versus the ipsilateral side (RR, 1.65; P = .0005), but different results were found in male athletes. (RR, 0.81; P = .21). There was no statistical difference in the incidence rate of ACL reinjury to either side in adolescent athletes (RR, 1.15; P = .28).

Conclusion

The contralateral ACL was more vulnerable to reinjury than the ipsilateral side in athletes after ACLR. Female athletes were more likely to reinjure their contralateral native ACL, while the same trend was not found in their male counterparts. The reinjury rate was comparable in both knees in adolescent athletes.

Remnant tissue enhances early postoperative biomechanical strength and infiltration of Scleraxis-positive cells within the grafted tendon in a rat anterior cruciate ligament reconstruction model

When ruptured, ligaments and tendons have limited self-repair capacity and rarely heal spontaneously. In the knee, the Anterior Cruciate Ligament (ACL) often ruptures during sports activities, causing functional impairment and requiring surgery using tendon grafts. Patients with insufficient time to recover before resuming sports risk re-injury. To develop more effective treatment, it is necessary to define mechanisms underlying ligament repair. For this, animal models can be useful, but mice are too small to create an ACL reconstruction model. Thus, we developed a transgenic rat model using control elements of Scleraxis (Scx), a transcription factor essential for ligament and tendon development, to drive GFP expression in order to localize Scx-expressing cells. As anticipated, Tg rats exhibited Scx-GFP in ACL during developmental but not adult stages. Interestingly, when we transplanted the flexor digitorum longus (FDP) tendon derived from adult Scx-GFP+ rats into WT adults, Scx-GFP was not expressed in transplanted tendons. However, tendons transplanted from adult WT rats into Scx-GFP rats showed upregulated Scx expression in tendon, suggesting that Scx-GFP+ cells are mobilized from tissues outside the tendon. Importantly, at 4 weeks post-surgery, Scx-GFP-expressing cells were more frequent within the grafted tendon when an ACL remnant was preserved (P group) relative to when it was not (R group) (P vs R groups (both n = 5), p<0.05), and by 6 weeks, biomechanical strength of the transplanted tendon was significantly increased if the remnant was preserved (P vsR groups (both n = 14), p<0.05). Scx-GFP+ cells increased in remnant tissue after surgery, suggesting remnant tissue is a source of Scx+ cells in grafted tendons. We conclude that the novel Scx-GFP Tg rat is useful to monitor emergence of Scx-positive cells, which likely contribute to increased graft strength after ACL reconstruction.

Early- and Late-Stage Benefits of Blood Flow Restriction Training on Knee Strength in Adolescents After Anterior Cruciate Ligament Reconstruction

Background

Blood flow restriction training (BFRT) after anterior cruciate ligament reconstruction (ACLR) is rising in popularity because of its benefits in reducing muscle atrophy and mitigating knee strength deficits.

Purpose

To investigate the impact BFRT has on adolescent knee strength after ACLR at 2 postoperative time points: at 3 months and the time of return to sport (RTS).

Study Design

Cohort study; Level of evidence, 3.

Methods

A prospective intervention (BFRT) group was compared to an age-, sex-, and body mass index-matched retrospective control group. Patients aged 12 to 18 years who underwent primary ACLR with a quadriceps tendon autograft were included. Along with a traditional rehabilitation protocol, the BFRT group completed a standardized BFRT protocol (3 BFRT exercises performed twice weekly for the initial 12 weeks postoperatively). Peak torque values for isometric knee extension and flexion strength (at 3 months and RTS) and isokinetic strength at 180 deg/s (at RTS) as well as Pediatric International Knee Documentation Committee (Pedi-IKDC) scores were collected. Differences between the BFRT and control groups were compared with 2-way mixed analysis of variance and 1-way analysis of variance.

Results

The BFRT group consisted of 16 patients (10 female; mean age, 14.84 ± 1.6 years) who were matched to 16 patients in the control group (10 female; mean age, 15.35 ± 1.3 years). Regardless of the time point, the BFRT group demonstrated significantly higher isometric knee extension torque compared to the control group (2.15 ± 0.12 N·m/kg [95% CI, 1.90-2.39] vs 1.74 ± 0.12 N·m/kg [95% CI, 1.49-1.98], respectively; mean difference, 0.403 N·m/kg; P = .024). The BFRT group also reported significantly better Pedi-IKDC scores compared to the control group at both 3 months (68.91 ± 9.68 vs 66.39 ± 12.18, respectively) and RTS (89.42 ± 7.94 vs 72.79 ± 22.81, respectively) (P = .047).

Conclusion

In adolescents, the addition of a standardized BFRT protocol to a traditional rehabilitation protocol after ACLR significantly improved knee strength and patient-reported function compared to a traditional rehabilitation program alone.

Effect of Age and Femoral Tunnel Drilling Technique on the Prevalence of Intra-articular Pathology at Both Primary and Revision ACL Reconstruction

Background

Studies have shown that meniscal and chondral lesions are more common at the time of revision anterior cruciate ligament reconstruction (ACLR) compared with primary surgery; however, few have evaluated the same patients through both primary and revision surgery.

Purpose

To describe the prevalence of meniscal and chondral lesions at the time of primary and subsequent revision ACLR and to determine the effect of age and femoral tunnel drilling technique on the development of intra-articular pathology over time.

Study Design

Case series; Level of evidence, 4.

Methods

All patients who had primary and subsequent revision ACLR in the same knee between 1997 and 2022 were identified from a prospectively collated database. The grading of chondral surfaces in each compartment, the presence of any meniscal tears, and treatment performed were recorded. Patients were grouped according to age and femoral tunnel drilling technique to allow subgroup analysis.

Results

Overall, 262 patients were included. Median age at primary surgery was 20.2 years. Lateral meniscal tears were more prevalent than medial tears at both primary (34.7% vs 28.2%; P = .11) and revision surgery (44.3% vs 40.8%; P = .43). Chondral lesions were most frequently found on the patella (8.8%) and the medial femoral condyle (MFC; 8.0%) at primary surgery. Between surgeries, new lesions developed most commonly on the MFC (13.0%) and the lateral femoral condyle (LFC; 11.1%). It was significantly more common for lateral meniscal tears treated with repair or left in situ at primary surgery to be healed at the time of revision surgery than medial tears (P = .01). Significantly more patients who had transtibial drilling of the femoral tunnel had a new meniscal tear at revision surgery (P = .001). Age did not have a significant influence on the prevalence of meniscal pathology.

Conclusion

The prevalence of intra-articular pathology increased between primary and revision ACLR. Lateral meniscal tears were more prevalent than medial tears at both surgeries. At revision surgery, new chondral lesions were more commonly found on the MFC than the LFC. The higher incidence of new meniscal tears observed in the transtibial group may reflect the more vertical graft orientation with this technique and its inferior ability to control rotation.

Pain Early After Anterior Cruciate Ligament Reconstruction is Associated With 6-Month Loading Mechanics During Running

BACKGROUND

Anterior cruciate ligament reconstruction (ACLR) results in persistent altered knee biomechanics, but contributing factors such as pain or patient function, leading to the altered loading, are unknown.

HYPOTHESIS

Individuals with worse self-reported pain after ACLR would have poorer biomechanics during running, and poor loading mechanics would be present in the ACLR limb compared with contralateral and control limbs.

STUDY DESIGN

Cohort pilot study.

LEVEL OF EVIDENCE

Level 3.

METHODS

A total of 20 patients after ACLR (age, 18.4 ± 2.7 years; height, 1.7 ± 0.1 m; mass, 84.2 ± 19.4 kg) completed visual analog scale and Knee Injury and Osteoarthritis Outcomes Score (KOOS) at 1 and 6 months postsurgery. At 6 months postsurgery, patients underwent biomechanical testing during running. A total of 20 control individuals also completed running biomechanical analyses. Associations between patient outcomes and biomechanics were conducted, and differences in running biomechanics between groups were analyzed.

RESULTS

KOOS pain score 1 month after surgery was associated with peak ACLR knee abduction moment (R2 = 0.35;P = 0.01). At 6-months, KOOS sport score was related to peak abduction moment in the ACLR limb (R2 = 0.23; P = 0.05). For change scores, the improvement in pain scores related to ACLR limb peak knee abduction moment (R2 = 0.55; P = 0.001). The ACLR limb had lower knee excursion, extension moments, and ground-reaction forces compared with the uninvolved and control limb. The uninvolved limb also had higher ground-reaction forces compared with the ACLR limb and control limb.

CONCLUSION

These results suggest that patient-reported outcomes 1 and 6 months after surgery are associated with running mechanics 6 months after ACLR. Further, the underloading present in the ACLR limb and overloading in the uninvolved limb indicates greater need for running rehabilitation after ACLR.

CLINICAL RELEVANCE

Understanding pain and how it may be linked to movement dysfunction is important for improving long-term outcomes.

The Effect of Staged Versus Usual Care Physiotherapy on Knee Function Following Anterior Cruciate Ligament Reconstruction

CONTEXT

The long duration and high cost of anterior cruciate ligament reconstruction (ACLR) rehabilitation can pose barriers to completing rehabilitation, the latter stages of which progress to demanding sport-specific exercises critical for a safe return to sport. A staged approach shifting in-person physiotherapy sessions to later months of recovery may ensure patients undergo the sport-specific portion of ACLR rehabilitation. Design/Objective: To compare postoperative outcomes of knee function in patients participating in a staged ACLR physiotherapy program to patients participating in usual care physiotherapy through a randomized controlled trial.

METHODS

One hundred sixty-two patients were randomized to participate in staged (n = 80) or usual care physiotherapy (n = 82) following ACLR and assessed preoperatively and postoperatively at 2 weeks, 6 weeks, 3 months, and 6 months. The staged group completed the ACLR rehabilitation protocol at home for the first 3 months, followed by usual care in-person sessions. The usual care group completed in-person sessions for their entire rehabilitation. Outcome measures included the Lower Extremity Functional Scale, International Knee Documentation Committee Questionnaire, pain, range of motion, strength, and hop testing.

RESULTS

There were no statistically significant between-group differences in measures of knee function at 6 months postoperative. Patients in the usual care group reported significantly higher International Knee Documentation Committee scores at 3 months postoperative (mean difference = 5.8; 95% confidence interval,  1.3 to 10.4; P = .01).

CONCLUSION

A staged approach to ACLR rehabilitation does not appear to impede knee function at 6 months postoperative but may result in worse patient reported outcomes at early follow-ups.

Concurrent Validity of The Expanded Cutting Alignment Scoring Tool (E-CAST)

Background

The Expanded Cutting Alignment Scoring Tool (E-CAST) has been previously shown to be reliable when assessing lower extremity alignment during a 45-degree sidestep cut, however, the validity of this tool remains unknown. The purpose of this study was to assess the concurrent validity of the E-CAST by comparing visually identified movement errors from two-dimensional (2D) video with three-dimensional (3D) biomechanical variables collected using motion capture.

Study Design

Cross Sectional.

Methods

Sixty female athletes (age 14.1 ± 1.5 years) who regularly participated in cutting/pivoting sports performed a sidestep cut with 2D video and 3D motion capture simultaneously recording. One clinician scored the 2D videos for each limb using the E-CAST criteria. Joint angles and moments captured in 3D were computed for the trunk and knee. Receiver operating characteristic (ROC) curve analyses were performed to determine the accuracy of each E-CAST item and to provide cut-off points for risk factor identification.

Results

ROC analyses identified a cut-off point for all biomechanical variables with sensitivity and specificity ranging from 70-85% and 55-89%, respectively. Across items, the area under the curve ranged from 0.67 to 0.91.

Conclusion

The E-CAST performed with acceptable to outstanding area under the curve values for all variables except static knee valgus.

Level of evidence

3b.

Risk Factors for Contralateral Tendon Rupture in Patients With Acute Achilles Tendon Rupture

The present study was performed to determine the incidence and risk factors of contralateral Achilles tendon rupture after an initial tendon rupture, and to identify the associated patient characteristics. Medical records of 181 adult patients with acute Achilles tendon rupture were reviewed. We investigated the risk factors for contralateral Achilles tendon rupture and calculated the incidence density (per 100 person-years), survival rate, hazard ratios, and 95% confidence intervals. The risk factors were extracted, including blood type, age, body mass index (BMI), occupation, underlying comorbidities, history of alcohol intake or smoking, injury mechanism, and fluoroquinolone antibiotic or steroid use. Military personnel and manual laborers, including farmers and firefighters were considered to have an occupation involving physical activity. Ten patients (5.5%) were identified as having nonsimultaneous, contralateral Achilles tendon rupture a mean of 3.3 years (range 1.0-8.3 years) after the initial tendon rupture. The incidence density of contralateral tendon rupture was 0.89 per 100 person-years. The 8-year survival rate of contralateral tendon rupture was 92.2%. Unadjusted and adjusted hazard ratios (with 95% confidence intervals, p value) of blood type O were 3.71 (1.07-12.82, p = .038) and 2.90 (0.81-10.32, p = .101), respectively, and those of occupations involving physical activity were 5.87 (1.64-20.98, p = .006) and 4.69 (1.27-17.28, p = .02), respectively. Based on the present data, blood type O and occupations involving physical activity are significantly associated with an increased risk of contralateral tendon rupture in adult patients who have sustained Achilles tendon rupture.

Risk Factors for Revision or Rerupture After Anterior Cruciate Ligament Reconstruction: A Systematic Review and Meta-analysis

BACKGROUND

The rerupture or need for revision after anterior cruciate ligament reconstruction (ACLR) is a serious complication. Preventive strategies that target the early identification of risk factors are important to reduce the incidence of additional surgery.

PURPOSE

To perform a systematic review and meta-analysis to investigate risk factors for revision or rerupture after ACLR.

STUDY DESIGN

Systematic review and meta-analysis; Level of evidence, 4.

METHODS

Literature searches were performed in PubMed, Embase, and Web of Science from database inception to November 2021 and updated in January 2022. Quantitative, original studies reporting potential adjusted risk factors were included. Odds ratios (ORs) were calculated for potential risk factors.

RESULTS

A total of 71 studies across 13 countries with a total sample size of 629,120 met the inclusion criteria. Fifteen factors were associated with an increase in the risk of revision or rerupture after ACLR: male sex (OR, 1.27; 95% CI, 1.14-1.41), younger age (OR, 1.07; 95% CI, 1.05-1.08), lower body mass index (BMI) (OR, 1.03; 95% CI, 1.00-1.06), family history (OR, 2.47; 95% CI, 1.50-4.08), White race (OR, 1.32; 95% CI, 1.08-1.60), higher posterolateral tibial slope (OR, 1.15; 95% CI, 1.05-1.26), preoperative high-grade anterior knee laxity (OR, 2.30; 95% CI, 1.46-3.64), higher baseline Marx activity level (OR, 1.07; 95% CI, 1.02-1.13), return to a high activity level/sport (OR, 2.03; 95% CI, 1.15-3.57), an ACLR within less than a year after injury (OR, 2.05; 95% CI, 1.81-2.32), a concomitant medial collateral ligament (MCL) injury (OR, 1.62; 95% CI, 1.31-2.00), an anteromedial portal or transportal technique (OR, 1.36; 95% CI, 1.22-1.51), hamstring tendon (HT) autografts (vs bone-patellar tendon-bone [BPTB] autografts) (OR, 1.60; 95% CI, 1.40-1.82), allografts (OR, 2.63; 95% CI, 1.65-4.19), and smaller graft diameter (OR, 1.21; 95% CI, 1.05-1.38). The other factors failed to show an association with an increased risk of revision or rerupture after ACLR.

CONCLUSION

Male sex, younger age, lower BMI, family history, White race, higher posterolateral tibial slope, preoperative high-grade anterior knee laxity, higher baseline Marx activity level, return to a high activity level/sport, an ACLR within less than a year from injury, a concomitant MCL injury, an anteromedial portal or transportal technique, HT autografts (vs BPTB autografts), allografts, and smaller graft diameter may increase the risk of revision or rerupture after ACLR. Raising awareness and implementing effective preventions/interventions for risk factors are priorities for clinical practitioners to reduce the incidence of revision or rerupture after ACLR.

Return to active duty after anterior cruciate ligament reconstruction (ACLR) in Chinese male military aircrews

Background

Surgically treated anterior cruciate ligament (ACL) injuries may be a waivable condition and allow return to full flight status, but waivers are based on expert opinion rather than recent published data. The purpose of this study was to evaluate return to flight after anterior cruciate ligament reconstruction (ACLR) in male military aircrews with ACL injuries and to identify factors that affect flight clearance.

Method

A single-center retrospective review was conducted by the authors for all active-duty aircrew who underwent ACLR at an authorized military medical center from January 2010 to December 2019. Demographic characteristics, occupational information, surgical data, and flight readiness evaluation outcomes were collected. Based on the final medical evaluation, subjects were divided into a qualified group (N = 64) and a disqualified group (N = 9), and the difference in data collected between the two groups was then analyzed to identify factors affecting flight clearance.

Results

A total of 73 patients underwent successful ACLR with a mean age of 31.6 ± 5.6 years. Non-contact injury was the main type of ACL injury, accounting for 84.9% of the total injuries. 55 cases (75.3%) occurred during daily sports activities and 18 (24.7%) during military training. 64 of the 73 crewmembers (87.7%) were able to return to flight at their last follow-up evaluation. The preoperative interval time (PIT) was significantly less in the qualified group than in the disqualified group (P = 0.002). Patients who underwent ACLR within three months were more likely to return to flying than those who underwent the procedure three months later (97.4% vs. 76.5%, P = 0.010). The incidence of failure to return to flight duty was significantly higher in aircrews with ACL injuries combined with meniscal injuries than in aircrews with isolated ACL injuries (21.4% vs. 0.0%, P = 0.017).

Conclusion

ACLR appears to be safe for military aircrew suffering ACL injuries with or without meniscal injury, and return to flight status is the most likely outcome for the majority of postoperative pilots. Prolonged PIT, PIT > 3 months, and ACL injury combined with meniscus injury had a negative impact on postoperative flight readiness.

No increase in adverse events with lateral extra-articular tenodesis augmentation of anterior cruciate ligament reconstruction - Results from the stability randomized trial

OBJECTIVES

Results from the Stability Study suggest that adding a lateral extra-articular tenodesis (LET) to a hamstring tendon autograft reduces the rate of anterior cruciate ligament reconstruction (ACLR) failure in high-risk patients. The purpose of this study is to report adverse events over the 2-year follow-up period and compare groups (ACLR alone vs. ACLR + LET).

METHODS

Stability is a randomized clinical trial comparing hamstring tendon ACLR with and without LET. Patients aged 14-25 years with an ACL deficient knee were included. Patients were followed and adverse events documented (type, actions taken, resolution) with visits at 3, 6, 12, and 24 months postoperatively. Adverse events were categorized as none, minor medical, minor surgical, contralateral ACL rupture, or graft rupture. Patient reported outcome measures (PROMs) collected at each visit included the Knee Injury and Osteoarthritis Outcome Score (KOOS), International Knee Documentation Committee Score (IKDC), and ACL Quality of Life Questionnaire (ACL-QOL).

RESULTS

In total, 618 patients were randomized (mean age 18.9 years, 302 (49%) male). Forty-five patients (7%) suffered graft rupture; 34 (11%) in the ACLR group compared to 11 (4%) in the ACLR + LET group (RRR = 0.67, 95% CI 0.36 to 0.83, p < 0.001). There were no differences in effusion or infection rates between groups. The ACLR + LET group experienced an increased number of hardware removals (10 vs. 4). Overall, the rate of minor medical events (11%), minor surgical events (7%), and ipsilateral or contralateral ACL tears (10%) were low considering the high-risk patient profile. Increasing severity of adverse events was associated with lower PROMs at 24 months post-operative. Patients in the ACLR + LET group reported greater degree of pain at 3 months only. There were no clinically significant differences in range of motion between groups.

CONCLUSIONS

The addition of LET to hamstring tendon autograft ACLR in young patients at high risk of re-injury resulted in a statistically significant reduction in graft rupture. While the addition of LET may increase rates of hardware irritation, there was no significant increase in overall rates of minor medical adverse events, minor surgical events, or overall re-operation rates. The concerns regarding complications associated with a LET did not materialize in this study.

LEVEL OF EVIDENCE

Level I.

LigaNET: A multi-modal deep learning approach to predict the risk of subsequent anterior cruciate ligament injury after surgery

Anterior cruciate ligament (ACL) injuries are a common cause of soft tissue injuries in young active individuals, leading to a significant risk of premature joint degeneration. Postoperative management of such injuries, in particular returning patients to athletic activities, is a challenge with immediate and long-term implications including the risk of subsequent injury. In this study, we present LigaNET, a multi-modal deep learning pipeline that predicts the risk of subsequent ACL injury following surgical treatment. Postoperative MRIs (n=1,762) obtained longitudinally between 3 to 24 months after ACL surgery from a cohort of 159 patients along with 11 non-imaging outcomes were used to train and test: 1) a 3D CNN to predict subsequent ACL injury from segmented ACLs, 2) a 3D CNN to predict injury from the whole MRI, 3) a logistic regression classifier predict injury from non-imaging data, and 4) a multi-modal pipeline by fusing the predictions of each classifier. The CNN using the segmented ACL achieved an accuracy of 77.6% and AUROC of 0.84, which was significantly better than the CNN using the whole knee MRI (accuracy: 66.6%, AUROC: 0.70; P<.001) and the non-imaging classifier (accuracy: 70.1%, AUROC: 0.75; P=.039). The fusion of all three classifiers resulted in highest classification performance (accuracy: 80.6%, AUROC: 0.89), which was significantly better than each individual classifier (P<.001). The developed multi-modal approach had similar performance in predicting the risk of subsequent ACL injury from any of the imaging sequences (P>.10). Our results demonstrate that a deep learning approach can achieve high performance in identifying patients at high risk of subsequent ACL injury after surgery and may be used in clinical decision making to improve postoperative management (e.g., safe return to sports) of ACL injured patients.

Chronological Changes in the Expression and Localization of Sox9 between Achilles Tendon Injury and Functional Recovery in Mice

Tendons help transmit forces from the skeletal muscles and bones. However, tendons have inferior regenerative ability compared to muscles. Despite studies on the regeneration of muscles and bone tissue, only a few have focused on tendinous tissue regeneration, especially tendon regeneration. Sex-determining region Y-box transcription factor 9 (Sox9) is an SRY-related transcription factor with a DNA-binding domain and is an important control factor for cartilage formation. Sox9 is critical to the early-to-middle stages of tendon development. However, how Sox9 participates in the healing process after tendon injury is unclear. We hypothesized that Sox9 is expressed in damaged tendons and is crucially involved in restoring tendon functions. We constructed a mouse model of an Achilles tendon injury by performing a 0.3 mm wide partial excision in the Achilles tendon of mice, and chronologically evaluated the function restoration and localization of the Sox9 expressed in the damaged sites. The results reveal that Sox9 was expressed simultaneously with the formation of the pre-structure of the epitenon, an essential part of the tendinous tissue, indicating that its expression is linked to the functional restoration of tendons. Lineage tracing for Sox9 expressed during tendon restoration revealed the tendon restoration involvement of cells that switched into Sox9-expressing cells after tendon injury. The stem cells involved in tendon regeneration may begin to express Sox9 after injury.

Recurrent Instability Rate and Subjective Knee Function following Accelerated Rehabilitation after ACL Reconstruction in Comparison to a Conservative Rehabilitation Protocol

INTRODUCTION

The Purpose of the present study was to assess the outcome of anterior cruciate ligament reconstruction (ACLR) with an accelerated rehabilitation protocol and to compare it to a conservative rehabilitation protocol. It was hypothesized that an accelerated rehabilitation protocol, including brace-free early weight bearing, would result in a higher rate of recurrent instability and revision surgery compared to a conservative rehabilitation protocol.

METHODS

From 2016 to 2017, two different rehabilitation protocols for isolated ACLR were used at a high-volume knee surgery center. A total of 65 consecutive patients with isolated hamstring ACLR, of whom n = 33 had been treated with an accelerated (AccRehab) and n = 32 with a conservative rehabilitation protocol (ConRehab), were retrospectively included in the study. Patients were evaluated for recurrent instability, revision surgery, and other complications at a mean follow-up period of 64 ± 7.4 months. In addition, Tegner Activity Scale, Lysholm Score, and IKDC-subjective Score were evaluated. Statistical comparison between the two groups was performed utilizing Fisher's exact test and Student's t-test.

RESULTS

Mean age (29.3 vs. 26.6 years) and preoperative Tegner Score (6.4 vs. 5.9) were comparable between both groups. At 64 ± 7.4 months after ACLR, six cases of recurrent instability were reported in the AccRehab group (18%) in comparison to three cases (9%) in the ConRehab group (p = n.s.). There was no significant difference regarding revision surgery and further complications. Furthermore, no significant difference was found between both groups regarding Tegner (5.5 ± 1.9 vs. 5.5 ± 1.2), Lysholm (93.6 ± 6.3 vs. 89.3 ± 10.7), and IKDC score (89.7 ± 7.9 vs. 86.7 ± 12.1).

CONCLUSION

No significant disadvantage of an accelerated rehabilitation protocol following ACLR was found in terms of recurrent instability rate, revision surgery, or patient-reported outcome. However, a trend towards a higher reinstability rate was found for an accelerated rehabilitation protocol. Future level one trials evaluating brace-free early weight bearing following ACLR are desirable.

Long-Term Bilateral Neuromuscular Function and Knee Osteoarthritis after Anterior Cruciate Ligament Reconstruction

Neuromuscular function is thought to contribute to posttraumatic osteoarthritis (PTOA) risk in anterior cruciate ligament (ACL)-reconstructed (ACLR) patients, but sensitive and easy-to-use tools are needed to discern whether complex muscle activation strategies are beneficial or maladaptive. Using an electromyography (EMG) signal analysis technique coupled with a machine learning approach, we sought to: (1) identify whether ACLR muscle activity patterns differed from those of healthy controls, and (2) explore which combination of patient outcome measures (thigh muscle girth, knee laxity, hop distance, and activity level) predicted the extent of osteoarthritic changes via magnetic resonance imaging (MRI) in ACLR patients. Eleven ACLR patients 10-15 years post-surgery and 12 healthy controls performed a hop activity while lower limb muscle EMG was recorded bilaterally. Osteoarthritis was evaluated based on MRI. ACLR muscle activity patterns were bilaterally symmetrical and differed from those of healthy controls, suggesting the presence of a global adaptation strategy. Smaller ipsilateral thigh muscle girth was the strongest predictor of inferior MRI scores. The ability of our EMG analysis approach to detect meaningful neuromuscular differences that could ultimately be related to thigh muscle girth provides the foundation to further investigate a direct link between muscle activation patterns and PTOA risk.

Differences in psychological readiness for return to sport after anterior cruciate ligament injury is evident in thigh musculature motor unit characteristics

Background

Following anterior cruciate ligament (ACL) injury, many athletes that undergo surgery and 6-9 months of rehabilitation struggle to return to sport. Evidence suggests that psychological factors contribute to this failure to return-to-sport.

Objective

Determine the motor control relationship between thigh musculature motor unit characteristics and psychological readiness to return to sport between ACL-injured and healthy controls.

Study design

A longitudinal cohort study.

Methods

Athletes longitudinally completed the ACL Return to Sport after Injury (ACL-RSI) survey and isometric strength measures with a measurement of electromyography (EMG) of the vastus lateralis, vastus medialis, biceps femoris, and semitendinosus. A score cut-off of 61 on the ACL-RSI was used to divide ACL-injured groups. EMG was decomposed to provide each identified motor unit's characteristics (amplitude, average firing rate, etc).

Results

Data demonstrated increased average firing rate for hamstrings (p<0.001), decreased average firing rate for vastus lateralis (p<0.001) and decreased motor unit size for both the quadriceps and hamstrings at return-to-sport post-ACL reconstruction compared with sex-matched and age-matched healthy controls (p<0.001). Furthermore, there were marked differences in disparate ACL-RSI scores between ACL-injured athletes.

Conclusions

At return to sport, ACL-injured athletes have major alterations of thigh musculature motor control, with smaller motor units used by those with low ACL-RSI scores. This study uniquely demonstrates objective thigh muscle motor unit characteristics that coincide with subjective reports of psychological readiness. This information will be important to address psychomotor complexes of injury for future rehabilitation protocols.

Comparison of Patient-Reported Outcomes, Strength, and Functional Performance in Primary Versus Revision Anterior Cruciate Ligament Reconstruction

BACKGROUND

Clinical outcomes after revision anterior cruciate ligament reconstruction (ACLR) are not well understood.

HYPOTHESIS

Patients undergoing revision ACLR would demonstrate worse patient-reported outcomes and worse limb symmetry compared with a cohort undergoing primary ACLR.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

672 participants (373 with primary ACLR, 111 with revision ACLR, and 188 uninjured) completed functional testing at a single academic medical center. Descriptive information, operative variables, and patient-reported outcomes (International Knee Documentation Committee score, Knee injury and Osteoarthritis Outcome Score, and Tegner Activity Scale score) were assessed for each patient. Quadriceps and hamstring strength tests were conducted using a Biodex System 3 Dynamometer. Single-leg hop for distance, triple hop test, and the 6-m timed hop test were also assessed. Limb symmetry index (LSI) between the ACLR limb and contralateral limb was calculated for strength and hop testing. Normalized peak torque (N·m/kg) was calculated for strength testing.

RESULTS

No differences were found in group characteristics, excluding body mass (P < .001), or in patient-reported outcomes. There were no interactions between revision status, graft type, and sex. Knee extension LSI was inferior (P < .001) in participants who had undergone primary (73.0% ± 15.0%) and revision (77.2% ± 19.1%) ACLR compared with healthy, uninjured participants (98.8% ± 10.4%). Knee flexion LSI was inferior (P = .04) in the primary group (97.4% ± 18.4%) compared with the revision group (101.9% ± 18.5%). Difference in knee flexion LSI between the uninjured and primary groups, as well as between the uninjured and revision groups, did not reach statistical significance. Hop LSI outcomes were significantly different across all groups (P < .001). Between-group differences in extension in the involved limb (P < .001) were noted, as the uninjured group exhibited stronger knee extension (2.16 ± 0.46 N·m/kg) than the primary group (1.67 ± 0.47 N·m/kg) and the revision group (1.78 ± 0.48 N·m/kg). As well, differences in flexion in the involved limb (P = .01) were found, as the revision group exhibited stronger knee flexion (1.06 ± 0.25 N·m/kg) than the primary group (0.97 ± 0.29 N·m/kg) and the uninjured group (0.98 ± 0.24 N·m/kg).

CONCLUSION

At 7 months postoperatively, patients who had undergone revision ACLR did not demonstrate inferior patient-reported outcomes, limb symmetry, strength, or functional performance compared with patients who had undergone primary ACLR. Patients who had undergone revision ACLR exhibited greater strength and LSI than their counterparts with primary ACLR, but these parameters were still inferior to those of uninjured controls.

Effect of Age and Sex on Psychological Readiness and Patient-Reported Outcomes 6 Months After Primary ACL Reconstruction

Background

Successful return to sport after anterior cruciate ligament (ACL) reconstruction (ACLR) can be affected by a patient's physical and psychological state throughout the rehabilitation process.

Purpose

To prospectively compare differences in patients at 6 months after primary ACLR with the ACL-Return to Sport after Injury (ACL-RSI), International Knee Documentation Committee (IKDC) or pediatric (Pedi)-IKDC, Hospital for Special Surgery Pediatric Functional Activity Brief Scale (Pedi-FABS), and Patient-Reported Outcomes Measurement Information System-Psychological Stress Experiences (PROMIS-PSE) scores.

Study Design

Prospective cohort study; Level of evidence, 2.

Methods

Patients enrolled were 8 to 35 years old who underwent primary ACLR and had their 6-month follow-up appointments between December 2018 and March 2020. Patients were divided into 3 age groups as follows: (1) preadolescents (10-14 years); (2) adolescents (15-18 years); and (3) adults (>18 years). Outcomes on the ACL-RSI, IKDC/Pedi-IKDC, Pedi-FABS, and PROMIS-PSE were compared according to age group, graft type (hamstring, patellar tendon, quadriceps, or iliotibial band autograft), and sex.

Results

A total of 176 patients (69 male, 107 female), with a mean age of 17.1 ± 3.1 years were included in the study. The mean ACL-RSI scores were significantly different among age groups (preadolescents, 75 ± 18.9; adolescents, 61.5 ± 20.4; and adults, 52.5 ± 19.8 [P < .001]) and graft types (P = .024). The IKDC and PROMIS-PSE scores were also significantly different among age groups (P < .001 and P = .044, respectively) and graft types (P = .034 and P < .001, respectively), with the iliotibial graft and the younger age group performing the best. There was no significant difference in the Pedi-FABS either by age group (P = .127) or graft type (P = .198). Female patients had lower ACL-RSI scores and higher (worse) scores on PROMIS-PSE than their male counterparts (P = .019 and P < .001, respectively), with no sex-based differences on IKDC or Pedi-FABS scores. The ACL-RSI and IKDC were positively correlated (Spearman r = 0.57; P < .001), while the ACL-RSI and PROMIS-PSE were negatively correlated (Pearson r = -0.34; P < .001).

Conclusion

This study suggests that psychological profiles and subjective perceptions of knee function 6 months after ACLR may vary in patients of different ages and between the sexes. Preadolescent patients had better scores on a majority of patient-reported outcomes compared with adolescent and adult patients.

Comparative study of the clinical efficacy of all-inside and traditional techniques in anterior cruciate ligament reconstruction

BACKGROUND

Many studies have focused on the femoral tunnel technique and fixation method, but few studies have involved the tibial tunnel technique and fixation method. The all-inside technique is one of the new techniques that has been described in recent years. All-inside anterior cruciate ligament (ACL) reconstruction is based on a tibial socket instead of a full tunnel. This method has many potential advantages.

AIM

To compare clinical outcomes of knee ACL autograft reconstruction using all-inside quadrupled semitendinosus (AIST) and traditional hamstring tendon (TBT) techniques.

METHODS

From January 2017 to October 2019, the clinical data of 80 patients with ACL reconstruction were retrospectively analyzed, including 67 males and 13 females. The patients had an average age of 24.3 ± 3.1 years (age range: 18-33 years). The AIST technique was used in 42 patients and the TBT technique was used in 38 patients. The time between operation and injury, operative duration, postoperative visual analogue scale (VAS) score and knee functional recovery were recorded and compared between the two groups. The International Knee Documentation Committee (IKDC) and Lysholm scoring system were used to comprehensively evaluate clinical efficacy.

RESULTS

Eighty patients were followed for 24-36 mo, with an average follow-up duration of 27.5 ± 1.8 mo. There were no significant differences in the time between surgery and injury, operative duration, IKDC and Lysholm scores of the affected knee at the last follow-up evaluation between the two groups. There were significant differences in VAS scores 1 d, 3 d, 7 d, 2 wk and 1 mo after surgery (P < 0.05). There was no significant difference in VAS score at 3 mo, 6 mo and 1 year after operation.

CONCLUSION

The efficacy of the AIST ACL reconstruction technique was comparable to the TBT technique, but the postoperative pain was less with the AIST technique. Thus, the AIST technique is an ideal treatment choice for ACL reconstruction.

Risk Factors for Sustaining a Second ACL Injury after Primary ACL Reconstruction in Female Football Players: A Study Investigating the Effects of Follow-Up Time and the Statistical Approach

BACKGROUND

Studies evaluating risk factors for sustaining an anterior cruciate ligament (ACL) injury have different, sometimes contrasting, results. Different follow-up times and statistical approaches may be a reason for these differences. The aim of this study was to explore if different follow-up times and statistical approaches, classification and regression tree (CART) analysis and Cox regression, would impact on the association between various candidate risk factors and ACL injury in female football players. In total, 112 active female football players, 18 ± 8 months after ACL reconstruction (mean age ± SD, 20 ± 2 years), were included and followed for at least 36 months. At baseline, all players underwent assessment of range of motion of knee and ankle joints, functional tests, and answered questionnaires regarding knee function, psychological and personality traits. Nineteen independent variables were included for the CART analysis and for univariable Cox regression and compared using four different follow-up times: 0-12, 0-24, 0-36, and 0->36 months.

RESULTS

Forty-three (38%) players sustained a second ACL injury. The identified risk factors varied depending on follow-up time both with CART analysis and with Cox regression. CART identified 12 of the 19 independent variables and selected between 5 and 6 of the variables in the four different follow-up times associated with second ACL injury. The accuracy of the different follow-up times for the CART varied between 86 and 93% with 77-96% sensitivity and 70-81% specificity. Cox regression identified two risk factors: knee extension at 0-36 months and 0->36 months, and time between primary injury and surgery at 0->36 months. The accuracy varied between 54 and 64% with 44-88% sensitivity and 32-71% specificity.

CONCLUSIONS

The identified risk factors associated with a second ACL injury varied depending on the follow-up time and statistical approach used. Thus, in future research on risk factors, the time athletes are followed up and the type of statistical methods used are important to discuss.

Intrinsic Risk Factors for First-Time Noncontact ACL Injury: A Prospective Study of College and High School Athletes

BACKGROUND

A comprehensive understanding of the intrinsic risk factors for anterior cruciate ligament (ACL) disruption is important for identifying individuals at increased risk for suffering this trauma and developing interventions to mitigate risk.

HYPOTHESIS

A variety of risk factors predispose athletes to first-time, noncontact ACL injury and some of these differ between male and female athletes.

STUDY DESIGN

Prospective cohort study with nested case-control sampling.

LEVEL OF EVIDENCE

Level 2.

METHODS

Sport teams at 28 high schools and 8 colleges were monitored prospectively over 4 years, and 109 of 130 athletes who suffered their first noncontact ACL injury participated in the study. At the time of injury, matched control subjects were randomly selected from among the case's teammates and a total of 227 athletes participated. Demographic characteristics, joint laxity, lower extremity alignment, strength, and personality characteristics were measured. The association of each risk factor with injury risk was assessed by conditional logistic regression.

RESULTS

The risk factors that were associated with ACL injury in both male and female athletes included having a parent with prior ACL injury and increases of the following variables: body weight, anterior displacement of the tibia relative to the femur, genu recurvatum, and generalized joint laxity. Risk factors that are unique to female athletes included increased body mass index, increased trunk flexion strength, and prior non-ACL knee injury. The risk factors specific to male athletes were decreased standing quadriceps angle, decreased hip adduction strength, and chronic disease.

CONCLUSION

A diverse set of risk factors predispose both male and female athletes to ACL injury, whereas others appear to be sex-specific.

CLINICAL RELEVANCE

Different approaches for assessing risk and preventing ACL injury are needed for male and female athletes. In addition, personalized prevention strategies may be needed to target the specific characteristics that place an individual at increased risk of suffering this trauma.

Recurrence quantification analysis of isokinetic strength tests: A comparison of the anterior cruciate ligament reconstructed and the uninjured limb

BACKGROUND

Despite widespread use of return to sport testing following anterior cruciate ligament reconstruction, studies suggest inadequacy in current testing criteria, such as limb symmetry index calculations, to determine athletes' readiness to return to play. Recurrence quantification analysis, an emerging non-linear data analysis tool, may reveal subtle neuromuscular differences between the injured and uninjured limb that are not captured by traditional testing. We hypothesized that isokinetic torque curve data of the injured limb would demonstrate lower determinism and entropy as compared to the uninjured limb.

METHODS

102 patients (44 M, 58F, 10 ± 1 months post-anterior cruciate ligament reconstruction) underwent isokinetic quadriceps strength testing using a HumacNorm dynamometer. Patients completed maximum effort knee extension and flexion at 60°/sec. Data were post-processed with a MATLAB CRQA Graphical User Interface and determinism and entropy values were extracted. Paired-sample t-tests (α = 0.05) were used to compare data from the injured and uninjured limb.

FINDINGS

Determinism and entropy values in the torque curves were lower in the injured limb than the uninjured limb (p < 0.001). Our findings indicate there is less predictability and complexity present in the torque signals of injured limbs.

INTERPRETATION

Recurrence quantification analysis can be used to assess neuromuscular differences between limbs in patients who have undergone anterior cruciate ligament reconstruction. Our findings offer further evidence that there are changes to the neuromuscular system which persist following reconstruction. Further investigation is needed to establish thresholds of determinism and entropy values needed for safe return to sport and to evaluate the utility of recurrence quantification analysis as a return to sport criterion.

Graft-Specific Surgical and Rehabilitation Considerations for Anterior Cruciate Ligament Reconstruction with the Quadriceps Tendon Autograft

Anterior cruciate ligament reconstruction (ACLR) with a bone-patellar tendon-bone (BPTB) or hamstring tendon (HT) autograft has traditionally been the preferred surgical treatment for patients returning to Level 1 sports. More recently, international utilization of the quadriceps tendon (QT) autograft for primary and revision ACLR has increased in popularity. Recent literature suggests that ACLR with the QT may yield less donor site morbidity than the BPTB and better patient-reported outcomes than the HT. Additionally, anatomic and biomechanical studies have highlighted the robust properties of the QT itself, with superior levels of collagen density, length, size, and load-to-failure strength compared to the BPTB. Although previous literature has described rehabilitation considerations for the BPTB and HT autografts, there is less published with respect to the QT. Given the known impact of the various ACLR surgical techniques on postoperative rehabilitation, the purpose of this clinical commentary is to present the procedure-specific surgical and rehabilitation considerations for ACLR with the QT, as well as further highlight the need for procedure-specific rehabilitation strategies after ACLR by comparing the QT to the BPTB and HT autografts.

Level of Evidence

Level 5.

Suture-tape augmentation of anterior cruciate ligament reconstruction: a prospective, randomised controlled trial (STACLR)

BACKGROUND

Anterior cruciate ligament (ACL) reconstruction aims to restore anteroposterior and rotatory stability to the knee following ACL injury. This requires the graft to withstand the forces applied during the process of ligamentisation and the rehabilitative period. We hypothesise that the use of suture tape augmentation of single bundle ACL reconstruction (ACLR) will reduce residual knee laxity and improve patient-reported outcomes at 2-year follow-up. We will conduct a 1:1 parallel arm single-centre randomised controlled trial comparing suture tape augmented ACLR to standard ACLR technique.

METHODS

The study design will be a parallel arm 1:1 allocation ratio randomised controlled trial. Sixty-six patients aged 18 and over waitlisted for primary ACLR will be randomised. Patients requiring osteotomy and extra-articular tenodesis and who have had previous contralateral ACL rupture or repair of meniscal or cartilage pathology that modifies the post-operative rehabilitation will be excluded. The primary outcome measure will be the side-to-side difference in anterior tibial translation (measured on the GNRB arthrometer) at 24 months post-surgery. GNRB arthrometer measures will also be taken preoperatively, at 3 months and 12 months post-surgery. Secondary outcomes will include patient-reported outcome measures (PROMs) collected online, including quality of life, activity and readiness to return to sport, complication rates (return to theatre, graft failure and rates of sterile effusion), examination findings and return to sport outcomes. Participants will be seen preoperatively, at 6 weeks, 3 months, 12 months and 24 months post-surgery. Participants and those taking arthrometer measures will be blinded to allocation.

DISCUSSION

This will be the first randomised trial to investigate the effect of suture-tape augmentation of ACLR on either objective or subjective outcome measures. The use of suture-tape augmentation in ACLR has been associated with promising biomechanical and animal-level studies, exhibiting equivalent complication profiles to the standard technique, with initial non-comparative clinical studies establishing possible areas of advantage for the technique. The successful completion of this trial will allow for an improved understanding of the in situ validity of tape augmentation whilst potentially providing a further platform for surgical stabilisation of the ACL graft.

TRIAL REGISTRATION

Australia New Zealand Clinical Trial Registry ACTRN12621001162808. Universal Trial Number (UTN): U1111-1268-1487. Registered prospectively on 27 August 2021.

Secondary Anterior Cruciate Ligament Injury Prevention Training in Athletes: What Is the Missing Link?

After reconstruction, the return to full competition rate of athletes is low, while the re-injury rate remains high despite the completion of a rehabilitation programme. Primary ACL prevention programmes are well developed, yet few research papers focus on secondary ACL injury prevention. The aim of current review is to determine if current ACL secondary prevention training has a positive influence on the re-injury rate, the clinical or functional outcomes, or the risk of re-injury in athletes. Studies investigating secondary prevention of ACL were searched in PubMed and EBSCOhost, followed by a review of the references in the identified articles. The existing evidence suggests that neuromuscular training, eccentric strengthening, and plyometric exercises may have a potential impact on improving biomechanical, functional, and psychological outcomes in athletes; however, the studies on the prevention of second ACL injury in athletes is scarce and inconclusive. Future research is needed to investigate the effectiveness of secondary ACL prevention in reducing the re-injury rates. (PROSPERO Registration number: CRD42021291308).

Predicting anterior cruciate ligament failure load with T2* relaxometry and machine learning as a prospective imaging biomarker for revision surgery

Non-invasive methods to document healing anterior cruciate ligament (ACL) structural properties could potentially identify patients at risk for revision surgery. The objective was to evaluate machine learning models to predict ACL failure load from magnetic resonance images (MRI) and to determine if those predictions were related to revision surgery incidence. It was hypothesized that the optimal model would demonstrate a lower mean absolute error (MAE) than the benchmark linear regression model, and that patients with a lower estimated failure load would have higher revision incidence 2 years post-surgery. Support vector machine, random forest, AdaBoost, XGBoost, and linear regression models were trained using MRI T2* relaxometry and ACL tensile testing data from minipigs (n = 65). The lowest MAE model was used to estimate ACL failure load for surgical patients at 9 months post-surgery (n = 46) and dichotomized into low and high score groups via Youden's J statistic to compare revision incidence. Significance was set at alpha = 0.05. The random forest model decreased the failure load MAE by 55% (Wilcoxon signed-rank test: p = 0.01) versus the benchmark. The low score group had a higher revision incidence (21% vs. 5%; Chi-square test: p = 0.09). ACL structural property estimates via MRI may provide a biomarker for clinical decision making.

Comparison of Dynamic Balance and Unilateral Hop Performance Between Women and Men Handball Players After Anterior Cruciate Ligament Reconstruction: A Pilot Study

CONTEXT

After anterior cruciate ligament reconstruction (ACLR), long-term functional deficiencies can occur, with controversial results reported when comparing women and men. Dynamic balance and unilateral hop test performance are considered important indicators for the risk of reinjury of the lower extremity. Although both sexes seem to have a similar risk to experience a second anterior cruciate ligament injury, sex-specific differences of dynamic balance and unilateral hop performance in handball players following ACLR are unknown.

OBJECTIVE

To compare dynamic balance and unilateral hop performance between women and men handball players at least 6 months after ACLR.

DESIGN

Cross-sectional pilot study.

PARTICIPANTS

Ten women (27.6 [4.5] y) and 10 men (26.5 [3.1] y) handball players 6 to 16 months after ACLR.

OUTCOME MEASURES

Dynamic balance and unilateral hop performance were assessed using the Y-Balance Test and the Single-Leg Hop for Distance Test.

RESULTS

Women players demonstrated significantly better results in the anterior direction of the Y-Balance Test for both legs compared with men players. Hop performance was not significantly different between sexes.

CONCLUSION

Dynamic balance and single-leg hop performance seem not to differ between women and men handball players 6 to 16 months after ACLR. The difference between sexes in the anterior reach direction of the Y-Balance Test should be considered small, rather than representing a true difference.

Return to Sport After Anterior Cruciate Ligament Reconstruction Requires Evaluation of >2 Functional Tests, Psychological Readiness, Quadriceps/Hamstring Strength, and Time After Surgery of 8 Months

PURPOSE

The purpose of this study was to examine the factors commonly used to determine readiness for return to sport (RTS) in the ACL reconstruction (ACL-R) patient population and assess which were most influential to successfully returning to sport and avoiding re-tear.

METHODS

The PUBMED, EMBASE and Cochrane Library databases were queried for studies related to RTS in ACL-R. Inclusion and exclusion criteria were applied to identify studies with greater than 1-year outcomes detailing the rate of return and re-tear given a described RTS protocol. Data of interest were extracted, and studies were stratified based on level of evidence and selected study features. Meta-analysis or subjective synthesis of appropriate studies was used to assess more than 25 potentially significant variables effecting RTS and re-tear.

RESULTS

After initial search of 1503 studies, 47 articles were selected for inclusion in the final data analysis, including a total of 1432 patients (31.4% female, 68.6% male). A meta-analysis of re-tear rate for included Level of Evidence 1 studies was calculated to be 2.8%. Subgroups including protocols containing a strict time until RTS, strength testing, and ≥2 dynamic tests demonstrated decreased RTS and re-tear heterogeneity from the larger group. Time to RTS, strength testing, dynamic functional testing, and knee stability were also found to be among the most prevalent reported criteria in RTS protocol studies.

CONCLUSIONS

This study suggests a multifactorial clinical algorithm for successful evaluation of RTS. The "critical criteria" recommended by the authors to be part of the postoperative RTS criteria include time since surgery of 8 months, use of >2 functional tests, psychological readiness testing, and quadriceps/hamstring strength testing in addition to the modifying patient factors of age and female gender.

LEVEL OF EVIDENCE

Level IV, systematic review of Level I-IV studies.

Clinical Outcomes After Anterior Cruciate Ligament Reconstruction in Patients With a Concomitant Segond Fracture: A Systematic Review

BACKGROUND

The Segond fracture can be observed in patients with an anterior cruciate ligament (ACL) tear. It is unclear whether the Segond fracture affects clinical outcomes after ACL reconstruction.

PURPOSE

To investigate whether the presence of a concomitant Segond fracture affects clinical outcomes after ACL reconstruction and to compare clinical outcomes when a Segond fracture is repaired surgically or left unrepaired.

STUDY DESIGN

Systematic review; Level of evidence, 4.

METHODS

Three databases (PubMed, Embase, Cochrane Library) were searched in accordance with the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines on July 27, 2020. Relevant studies regarding ACL injury with concomitant Segond fracture treated by primary ACL reconstruction were screened in duplicate. Data regarding patient characteristics and clinical outcomes were extracted. Descriptive data are presented, and a random-effects model was used to pool amenable data.

RESULTS

A total of 5 studies examining 2418 patients (987 female; 40.8%), mean age 25.4 years, were included in this study. There were 304 patients with a Segond fracture (mean age, 28.1 years; 35.9% female) and 2114 patients without a Segond fracture (mean age, 25.1 years; 41.5% female). Four studies directly compared outcomes between patients with an unrepaired Segond fracture and no Segond fracture. One study reported 12 patients who underwent ACL reconstruction and repair of a Segond fracture. Among 4 studies, 11 of 292 (3.8%) graft failures/revision surgeries were reported in the groups that had Segond fracture, whereas 145 of 2114 (6.9%) graft failures/revision surgeries were reported in groups that did not have Segond fracture. No significant difference was observed in the risk of graft failure between the 2 groups, with a pooled risk ratio of 0.59 (95% CI, 0.32-1.07; P = .08; I2 = 0%). No clinically significant differences were observed with regard to International Knee Document Committee score, Lysholm score, Tegner activity scale, and postoperative knee laxity between the group with Segond fracture and those without.

CONCLUSION

An unrepaired Segond fracture does not appear to have any significant negative effect on postoperative stability or risk of graft failure or revision surgery after ACL reconstruction. Future prospective studies may be warranted to confirm the finding that patients with combined ACL injury and Segond fracture may have outcomes comparable with those of ACL-injured patients without a Segond fracture when isolated ACL reconstruction is performed.

Doxycycline Promotes Graft Healing and Attenuates Posttraumatic Osteoarthritis After Anterior Cruciate Ligament Reconstruction in a Rat Model

BACKGROUND

Doxycycline (Doxy) has been shown to facilitate tendon healing by reducing on-site matrix metalloproteinase (MMP) activity, but its effect on graft healing after anterior cruciate ligament reconstruction (ACLR) has not been investigated, and the therapeutic effect of Doxy in preventing ACLR-induced posttraumatic osteoarthritis (PTOA) is unclear.

HYPOTHESIS

Doxy promotes graft healing and alleviates the progression of PTOA after ACLR.

STUDY DESIGN

Controlled laboratory study.

METHODS

Sprague Dawley rats (n = 74; age, 12-13 weeks; male) that underwent ACLR were divided into untreated control and Doxy treatment (50 mg/kg/d orally until sacrifice) groups. At 2 and 6 weeks after surgery, graft healing was assessed by biomechanical testing, histology, immunohistochemical staining, and micro-computed tomography (μCT). The progression of PTOA was evaluated at 6 weeks by histology, the Mankin score, and immunofluorescence staining of the tibial plateau, and osteophyte formation was evaluated by μCT. Hindlimb weight distribution was evaluated at 6 weeks, and gait patterns were evaluated at 2 and 6 weeks. Intra-articular MMP activity was evaluated at 6 weeks in vivo using an MMP-activatable near-infrared fluorescent probe.

RESULTS

Graft healing was enhanced by Doxy treatment, and the ultimate failure load (P = .002) and stiffness of the graft (P = .007) were significantly higher in the Doxy group at week 2. Bone mineral density and bone volume/total volume for both the tibial and the femoral tunnels at week 6 in the Doxy group were significantly higher compared with in the control group (P < .05). The overall graft healing scores were significantly higher in the Doxy group. Doxy treatment enhanced graft integration, intratunnel graft integrity, and collagen birefringence; more collagen types 1 and 10 and less MMP-13 were found at the graft-bone interface. At week 6, the Doxy group had a lower modified Mankin score (P = .033) and showed fewer MMP 13-positive chondrocytes at the articular cartilage surface (P = .002), indicating moderate joint cartilage damage. μCT revealed less osteophyte formation, and gait analysis revealed more symmetric weightbearing and gait patterns, after Doxy treatment at week 6 (P < .05). In vivo imaging with the near-infrared fluorescent probe identified significantly lower intra-articular MMP activity in the Doxy group at week 6 (P = .016).

CONCLUSION

The oral administration of Doxy was able to synchronously promote graft healing and attenuate PTOA in an ACLR rat model.

CLINICAL RELEVANCE

Our results indicated that Doxy, a widely used drug, is potentially beneficial to patients after ACLR.

Application of the 3D-MRI on post-operative graft assessment in adolescent patients with ACL reconstruction: A minimal 2-year follow-up

Background

The purpose of the present study was to assess the prognostic morphological changes of the reconstructed hamstring auto-grafts by using reconstructed three-dimensional MRI (3D-MRI) in adolescent patients with ACLR.

Methods

22 adolescent patients (less than 17 years old) were retrospective included between January 1, 2018, and October 31, 2020, in our department. The patients were divided into 2 subgroups: subgroup A (<14 years old) and subgroup B (≥14 years old). 3D-MRI was used to detect the total cross-sectional area (TCA) and long-to-short axis (LSA) ratio of the reconstructed ACL graft at the proximal, mid-point, and distal regions. The minimal follow-up was 2 years.

Results

The averaged follow-up of subgroup A and B was 37.8 ± 5.6 and 37.6 ± 6.5 months, respectively. Comparing to the initial graft (ACLR operation), the TCA of reconstructed ACL was increased by 30.6% on average, and the TCAs at proximal, mid-point, and distal regions were increased by 56.4%, 50.0%, and 17.7%, respectively, inner-group comparisons showed that the TCAs of the 3 region in subgroup A were all increased at the follow-up (P = 0.002) (P < 0.001) (P < 0.001), however, only increased mid-point (P = 0.024) and distal TCAs (P < 0.001) were found in subgroup B. Comparing to the native ACL, the proximal LSA ratio in subgroup A was comparable, while it was lower in subgroup B than the native ACL (P = 0.004), the distal LSA ratios in the 2 subgroups were both lower than the native ACL (P = 0.004) (P = 0.006).

Conclusions

3D-MRI assessment can exactly identify the morphological changes of the graft in adolescent patients with ACLR, the TCA of the constructed ACL was increased compared to the initial graft, however, the LSA ratio was still lower than the native ACL. Younger adolescent patients may have a better potential on the ligamentization after ACLR than the older adolescent patients.

A clinician-friendly test battery with a passing rate similar to a 'gold standard' return-to-sport test battery 1 year after ACL reconstruction: Results from a rehabilitation outcome registry

OBJECTIVES

To 1) present passing rates for different clinician-friendly (CF) test batteries and 2) determine the relationship between passing CF test batteries and passing gold standard (GS) return-to-sport (RTS) muscle function testing, 1 year after ACL reconstruction.

STUDY DESIGN

Cross-sectional registry study, level of evidence: 3.

SETTING

Primary care.

PARTICIPANTS

Data from 588 patients (52% women, mean age 29.3 ± 9.8 years) were extracted from the Project ACL registry.

MAIN OUTCOME MEASURES

The passing rates for the different test batteries.

RESULTS

The passing rate for GS test battery was 28% (95% CI, 24-32%) and the passing rate for the CF test battery with the lowest passing rate was 27% (95% CI 24-31%). The two CF test batteries with the strongest relationships with passing GS test battery showed that 51% (95% CI 43-59%) and 49% (95% CI 44-55%) of the patients who passed the respective CF test battery also passed the GS test battery.

CONCLUSION

A CF test battery can be as demanding to pass as a GS test battery, 1 year after ACL reconstruction. However, passing a CF test battery only gives patients a chance similar to a "coin flip" of also passing a GS RTS test battery.

EVALUATION OF THE ANTEROLATERAL LIGAMENT OF THE KNEE IN MAGNETIC RESONANCE MRI: CASE SERIES

Objective

To evaluate the citation of the ligament in the magnetic resonance imaging (MRI) reports and confirm its presence and injury in the images of exams performed in the acute phase retrospectively.

Methods

In total, 103 patients who underwent anterior cruciate ligament (ACL) reconstruction in 2019 were included. The images were reanalyzed by two radiologists.

Results

In the first analysis, only one report mentioned the anterolateral ligament (ALL) and its injury (0.97%). On reanalysis, ALL was visualized in almost all cases (95% and 97%). An injury was found in 53 (51.5%) cases by radiologist A and in 56 (54.4%) cases by radiologist B. The injury was diagnosed by both in 39 (37.9%) cases (p < 0.0001). Radiologists disagreed regarding the injury (Kappa = 0.411).

Conclusion

The reports failed to describe the ligament and diagnose a significant number of injuries. The analysis of conventional resonance images still presents divergences in the diagnosis of ALL injury associated with the ACL among radiologists. Level of Evidence IV, Case Series.

Return to Sports: A Risky Business? A Systematic Review with Meta-Analysis of Risk Factors for Graft Rupture Following ACL Reconstruction

BACKGROUND

The risk of sustaining a graft rupture after anterior cruciate ligament reconstruction (ACLR) is high. Contributing risk factors are, however, still not clearly identified.

OBJECTIVE

The aim of this systematic review was to identify and quantify risk factors for graft rupture after ACLR.

METHODS

A systematic review with meta-analysis (PROSPERO CRD42020140129) based on PRISMA guidelines was performed. MEDLINE, CINAHL and EMBASE were searched from inception to September 2021. Prospective and retrospective studies addressing risk factors for graft rupture after ACLR in males/females of all ages were considered. Meta-analyses using a random effect model (effect measure: odds ratio [OR] with 95% confidence interval [CI]) were performed. The GRADE tool was used to assess evidence quality.

RESULTS

Following full-text screening of 310 relevant papers, 117 were eventually included, incorporating up to 133,000 individuals in each meta-analysis. Higher Tegner activity level (≥ 7 vs < 7) at primary injury (OR 3.91, 95% CI 1.69-9.04), increased tibial slope (degrees) (OR 2.21, 95% CI 1.26-3.86), lower psychological readiness to return to sport (RTS) (OR 2.18, 95% CI 1.32-3.61), early surgery (< 12 vs ≥ 12 months) (OR 1.87, 95% CI 1.58-2.22), RTS (pre-injury level) (OR 1.87, 95% CI 1.21-2.91) and family history of ACL injury (OR 1.76, 95% CI 1.34-2.31) were all associated with increased odds of graft rupture. Higher age (OR 0.47, 95% CI 0.39-0.59), female sex (OR 0.88, 95% CI 0.79-0.98), fewer self-reported knee symptoms pre-reconstruction (OR 0.81, 95% CI 0.69-0.95) and concomitant cartilage injuries (OR 0.70, 95% CI 0.62-0.79) instead decreased the odds. Meta-analysis revealed no association between body mass index, smoking, joint laxity, RTS time, knee kinematics, muscle strength or hop performance and graft rupture.

CONCLUSION

Conspicuous risk factors for graft rupture were mainly sports and hereditary related. Few studies investigated function-related modifiable factors or included sports exposure data.

Global research status of anterior cruciate ligament reconstruction: a bibliometric analysis

Purpose

The aim of this study is to comprehensively analyze the publications of anterior cruciate ligament reconstruction (ACLR) research and display the current research status in this field.

Methods

Articles regarding ACLR research published before October 7, 2021, were downloaded from the Web of Science Core Collection. Excel 2016 and Bibliometric website were used to analyze the annual article trends and international cooperation network. CiteSpace V and VOSviewer were used to perform co-occurrence and citation analyses for journals, institutions, authors, cocitation authors and keywords. Burst keyword detection was also performed with CiteSpace V.

Results

A total of 12 223 ACLR articles were identified. The American Journal of Sports Medicine (1636 publications, 92,310 citations), the Pennsylvania Commonwealth System of Higher Education (624 publications, 25,304 citations) and Freddie H. Fu (321 publications, 15,245 citations) were journals, institutions and authors with the most publications and citations, respectively. Patellar tendon was the keyword with the most occurrences (1618 times) and return to sport was the keyword with the most burst strength (burst strength: 46.99).

Conclusion

ACLR-related publications showed a rapid increasing trend since 1990. A large number of articles have been published by authors from different institutions and countries, some of which have gained great academic influence. Based on keyword analysis, patellar tendon is identified as the research hotspot and return to sport is identified as the current research frontier.

Angular Velocities and Linear Accelerations Derived from Inertial Measurement Units Can Be Used as Proxy Measures of Knee Variables Associated with ACL Injury

Given the high rates of both primary and secondary anterior cruciate ligament (ACL) injuries in multidirectional field sports, there is a need to develop easily accessible methods for practitioners to monitor ACL injury risk. Field-based methods to assess knee variables associated with ACL injury are of particular interest to practitioners for monitoring injury risk in applied sports settings. Knee variables or proxy measures derived from wearable inertial measurement units (IMUs) may thus provide a powerful tool for efficient injury risk management. Therefore, the aim of this study was to identify whether there were correlations between laboratory-derived knee variables (knee range of motion (RoM), change in knee moment, and knee stiffness) and metrics derived from IMUs (angular velocities and accelerations) placed on the tibia and thigh, across a range of movements performed in practitioner assessments used to monitor ACL injury risk. Ground reaction forces, three-dimensional kinematics, and triaxial IMU data were recorded from nineteen healthy male participants performing bilateral and unilateral drop jumps, and a 90° cutting task. Spearman's correlations were used to examine the correlations between knee variables and IMU-derived metrics. A significant strong positive correlation was observed between knee RoM and the area under the tibia angular velocity curve in all movements. Significant strong correlations were also observed in the unilateral drop jump between knee RoM, change in knee moment, and knee stiffness, and the area under the tibia acceleration curve (r_s = 0.776, r_s = -0.712, and r_s = -0.765, respectively). A significant moderate correlation was observed between both knee RoM and knee stiffness, and the area under the thigh angular velocity curve (r_s = 0.682 and r_s = -0.641, respectively). The findings from this study suggest that it may be feasible to use IMU-derived angular velocities and acceleration measurements as proxy measures of knee variables in movements included in practitioner assessments used to monitor ACL injury risk.

Repeat Anterior Cruciate Ligament Injury and Return to Sport in Australian Soccer Players After Anterior Cruciate Ligament Reconstruction With Hamstring Tendon Autograft

BACKGROUND

Soccer is the most commonly played team sport in the world and a high-risk sport for anterior cruciate ligament (ACL) injury and subsequent ACL reconstruction (ACLR).

PURPOSE

To assess the rate of further ACL injury in patients who have undergone ACLR with hamstring tendon autograft after soccer injuries in Australia and to determine factors associated with repeat ACL injury and return to soccer.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

From a prospectively collected database, a series of 1000 consecutive ACLRs using hamstring autografts performed in soccer players were identified. Patients were surveyed at a minimum 5 years after reconstruction, including details of further ACL injuries to either knee, return to soccer or other sports, and psychological readiness per the Anterior Cruciate Ligament Return to Sport after Injury (ACL-RSI) scale.

RESULTS

Of the 862 participants reviewed, ACL graft rupture occurred in 85 (10%) and contralateral ACL rupture in 68 (8%) within 5 years after the reconstruction. The 5-year ACL graft survivorship was 94% for females and 88% for males. The survivorship of the contralateral ACL was 92% for males and 90% for females. When compared with those aged >25 years, the odds of ACL graft rupture was increased by 4 to 5 times in those aged 19 to 25 years and 3 to 7 times in those ≤18 years. Further ACL injury to the graft or contralateral knee occurred in 44% of males aged ≤18 years. Risk factors for further ACL injury were younger age at time of surgery, male sex, and return to soccer. Graft diameter did not influence ACL graft rupture rates, and 70% of patients returned to soccer after ACLR. The mean ACL-RSI score was 59, and patients who reported more fear of reinjury on this scale were less likely to have returned to soccer.

CONCLUSION

The prevalence of ACL graft rupture (10%) and contralateral ACL rupture (8%) was near equivalent over 5 years in this large cohort of mostly recreational Australian soccer players. ACLR with hamstring autograft is a reliable procedure, allowing 70% of patients to return to soccer in this high-risk population. Risk factors for further ACL injury are progressively younger age at time of surgery, male sex, and return to soccer. Graft diameter was not a factor in ACL graft rupture, indicating that other factors, particularly age, are of primary importance.

Environmental Risk Factors for Osteoarthritis: The Impact on Individuals with Knee Joint Injury

Osteoarthritis is a debilitating chronic condition involving joint degeneration, impacting over 300 million people worldwide. This places a high social and economic burden on society. The knee is the most common joint impacted by osteoarthritis. A common cause of osteoarthritis is traumatic joint injury, specifically injury to the anterior cruciate ligament. The purpose of this review is to detail the non-modifiable and modifiable risk factors for osteoarthritis with particular focus on individuals after anterior cruciate ligament injury. After reading this, health care providers will better comprehend the wide variety of factors linked to osteoarthritis.

Reliability of MRI Detection of Kaplan Fiber Injury in Pediatric and Adolescent Patients with ACL Tears

Background:

While studies have described Kaplan fiber (KF) injury in up to 60% of adults with anterior cruciate ligament (ACL) tears, the incidence of KF injury in the pediatric and adolescent population remains unknown.

Purpose:

To (1) determine the reliability of using magnetic resonance imaging (MRI) to identify KF injury in the pediatric and adolescent population and (2) define the incidence of KF injury in these patients with acute ACL injuries.

Study Design:

Cohort study (diagnosis); Level of evidence, 3.

Methods:

The authors retrospectively identified patients ≤18 years of age who underwent ACL reconstruction for acute tears between 2013 and 2020. All preoperative MRI scans were reviewed independently and in a blinded fashion by 2 musculoskeletal radiologists, who noted the presence of the KF complex and any evidence of injury; interrater reliability was assessed. Patient characteristics, time from injury to MRI, laterality, and concomitant ligamentous or meniscal injuries were recorded, and associations between patient or injury characteristics and KF integrity on MRI were assessed.

Results:

In total, 51 patients (mean age, 14.9 years) met the inclusion criteria. Of these, 27 patients were female and 31 sustained an injury to the right knee. With respect to KF integrity, radiologist 1 visualized KF injury in 29% of patients, while radiologist 2 visualized KF injury in 35% of patients. In 12% of cases for radiologist 1 and 6% of cases for radiologist 2, KFs were unable to be visualized at all. The overall percentage agreement between the 2 radiologists was 76.5% with a kappa statistic of 0.57 (moderate agreement). There were no significant associations found between the presence of KF injury and patient age, sex, laterality, body mass index, concomitant ligamentous injury, or meniscal injury. However, visualization of KF injury on MRI was associated with a shorter time from index injury to MRI (15 days vs 23 days; P = .044).

Conclusion:

Approximately one-third of pediatric and adolescent patients who underwent ACL reconstruction were found to have KF injuries. Standard preoperative MRI scans can reliably be used to visualize KF injury in the majority of pediatric and adolescent patients with ACL tears, especially when the MRI is performed in the acute setting.

Side-to-side differences in knee laxity and side hop test may predispose an anterior cruciate ligament reinjury in competitive adolescent alpine skiers

An anterior cruciate ligament (ACL) injury is a common, severe injury in alpine skiing, and anterior cruciate ligament reconstruction (ACLR) is frequently performed in competitive alpine skiers younger than 20 years old. To reduce the reinjury rate, both intrinsic and extrinsic risk factors should be examined. The aim of this study was to investigate possible intrinsic risk factors for an ACL reinjury in competitive alpine skiers. A cohort of 384 alpine skiers (191 males/193 females) from the Swedish ski high schools were prospectively followed during their high school years. The students were clinically examined and physically tested prior to each ski season. In addition, the RAND 36-Item health survey 1.0 (SF-36, Copyright 1994 Medical Outcome Trust, distributed by RAND Corporation) and injuries were prospectively registered. Thirty-one of the skiers (five males/26 females) had undergone an ACLR before entering the ski high school. This cohort was analyzed with respect to the occurrence of, and possible risk factors for an ACL reinjury (including ipsilateral and contralateral ACL injuries). Skiers who sustained an ACL reinjury were called the “ACL reinjury group,” and those who did not sustain an ACL reinjury were called the “ACL injury group.” Notably, 12 of the 31 students (39%), ten female and two male skiers, aged 16.5 (SD 0.5) years, sustained an ACL reinjury during the two first years at the ski high school. In addition, 10 of the 12 ACL reinjuries occurred within 10–23 months from the first injury [m 14.8 (SD4.7)] and two ACL reinjuries occurred at 29 and 47 months, respectively, from the first injury. It is noted that eight of the ACL reinjuries were to the ipsilateral knee and four to the contralateral knee. There were no differences between the groups with respect to muscle flexibility in the lower extremity, Beighton score, and one leg hop for distance or square hop test. Side-to-side differences were found with respect to knee joint laxity, >3 mm, measured with KT-1000 arthrometer (p = 0.02), and the side hop test (p = 0.04). RAND 36-Item health survey did not predict an ACL reinjury. In conclusion, a side-to-side difference in the side hop test and knee joint laxity (KT-1000) may predispose an ACL reinjury in competitive adolescent alpine skiers.

Association of Smoking With Graft Rupture After Anterior Cruciate Ligament Reconstruction

Background

The effect of smoking on graft rupture after anterior cruciate ligament (ACL) reconstruction is not well understood.

Hypothesis

It was hypothesized that there will be no relationship between tobacco use and graft rupture after ACL reconstruction, as reflected by postoperative magnetic resonance imaging (MRI) and arthroscopic examination.

Study Design

Cohort study; Level of evidence, 3.

Methods

Included were 233 patients who received primary ACL reconstruction with hamstring tendon autograft between January 1, 2013, and December 31, 2019, and who underwent MRI evaluation at 20.2 ± 1.9 months postoperatively. The patients were categorized by smoking history into 2 groups: 39 smokers and 194 nonsmokers. The 2 groups did not differ significantly in age, sex, operative technique, preinjury Tegner score, or mean time until postoperative MRI. The primary outcome was graft rupture rate, with rupture confirmed by either arthroscopic assessment or postoperative MRI diagnosis. The secondary outcome measure was degree of graft ligamentization, evaluated by measuring the signal-to-noise quotient (SNQ) of the graft.

Results

The overall ACL graft rupture rate was 6.0%. The rupture rate was significantly higher in smokers than in nonsmokers (12.8% vs 4.6%, respectively; P = .0498). Smokers also had a significantly higher whole-graft SNQ compared with nonsmokers (4.7 ± 4.4 vs 3.3 ± 3.7, respectively; P = .028), suggesting less satisfactory ligamentization in smokers.

Conclusion

Smoking was associated with a higher risk of graft rupture of ACL reconstruction and a higher SNQ of the intact graft as shown on postoperative MRI.

Combined ACL and ALL reconstruction reduces the rate of reoperation for graft failure or secondary meniscal lesions in young athletes

PURPOSE

Graft failure and secondary meniscal tears are major concerns after anterior cruciate ligament (ACL) reconstruction in young athletes. The aim was to evaluate the link between ACL reconstruction with and without anterolateral ligament (ALL) reconstruction and outcomes in young patients participating in pivoting sports.

METHODS

This was a retrospective study of data collected prospectively. Patients less than 20 years, involved in pivoting sports and undergoing primary ACL reconstruction with a quadruple hamstring tendon (4HT) graft or 4HT graft combined with anterolateral ligament reconstruction (4HT + ALL) were included. Survival analysis was performed to identify the prognostic indicators for reoperation due to graft failure or secondary meniscal lesions. Knee laxity was assessed and patient reported outcome measures (PROMs) were collected.

RESULTS

A total of 203 patients (mean (± SD) age: 16.3 ± 2 years) with a mean follow-up of 4.8 ± 0.9 (range: 3.3‒6.8) years were included. There were 101 4HT and 102 4HT + ALL grafts. Graft rupture rates were 11.9% for 4HT grafts and 5.8% for 4HT + ALL grafts (n.s.). There were 9.9% secondary meniscal procedures for 4HT grafts vs. 1.9% for 4HT + ALL grafts (p = 0.02). With reoperation for graft failure or secondary meniscal lesions at final follow-up as the endpoint, survival was better in the 4HT + ALL group (91.4% vs. 77.8%, respectively; p = 0.03). Absence of ALL reconstruction (HR = 4.9 [95%CI: 1.4-17.9]; p = 0.01) and preoperative side-to-side laxity > 3 mm (HR = 3.1 [95%CI: 1.03-9.1]; p = 0.04) were independently associated with an increased rate of reoperations. Mean (± SD) side-to-side laxity was 1.3 ± 1.3 mm (range: - 2 to 5) for 4HT grafts vs. 0.9 ± 1.3 mm (range: - 6 to 4.8) for 4HT + ALL grafts (n.s.) 6 months post-surgery. The rate of return to the same sport at the same level was 42.2% for 4HT grafts vs. 52% for 4HT + ALL grafts (n.s.). There was no significant difference in subjective outcomes including PROMs between the two groups.

CONCLUSION

Combined ALL + ACL reconstruction reduced the rate of graft failure and secondary meniscal injury in young athletes when compared to ACL reconstruction alone. Subjective results were comparable, with a similar rate of complications. Combined reconstruction should be preferred in this young population.

LEVEL OF EVIDENCE

Level IV.

Risk Factors for Anterior Cruciate Ligament Graft Failure in Professional Athletes: An Analysis of 342 Patients With a Mean Follow-up of 100 Months From the SANTI Study Group

BACKGROUND

Anterior cruciate ligament (ACL) injuries are among the most common knee injuries sustained in elite sport, and athletes generally undergo ACL reconstruction (ACLR) to facilitate their return to sport. ACL graft rupture is a career-threatening event for elite athletes.

PURPOSE/HYPOTHESIS

The purpose of this study was to determine the risk factors for graft failure in professional athletes undergoing ACLR. It was hypothesized that athletes who underwent combined ACLR with a lateral extra-articular procedure (LEAP) would experience significantly lower rates of graft rupture in comparison with those who underwent isolated ACLR.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Professional athletes who underwent primary ACLR with a minimum follow-up of 2 years were identified from the Santy database. Patients were excluded if they underwent major concomitant procedures, including multiligament reconstruction surgery or osteotomy. Further ipsilateral knee injury, contralateral knee injury, and any other reoperations or complications after the index procedure were identified by interrogation of the database and review of the medical notes.

RESULTS

A total of 342 athletes with a mean follow-up of 100.2 ± 51.9 months (range, 24-215 months) were analyzed. Graft failures totaling 31 (9.1%) were reported, requiring revision surgery because of symptomatic instability. The rate of graft failure was significantly higher when ACLR was not combined with a LEAP (15.5% vs 6.0%; P = .0105) and in athletes aged 21 years or younger (13.8% vs 6.6%; P = .0290). A multivariate analysis was performed using the Cox model and demonstrated that athletes undergoing an isolated ACLR were at >2-fold risk of ACL graft rupture (hazard ratio [HR], 2.678 [1.173; 4.837], P = .0164) when compared with those undergoing a combined ACLR with a LEAP. Additionally, athletes aged ≤21 years were also at >2-fold risk of graft failure (HR, 2.381 [1.313; 5.463]; P = .0068) than those aged >21 years. Sex, sport, and graft type were not found to be significant risk factors for graft failure.

CONCLUSION

Professional athletes undergoing isolated ACLR and aged ≤21 years are at >2-fold greater risk of graft failure. Orthopaedic surgeons treating elite athletes should combine an ACLR with a LEAP to improve ACL graft survivorship.

Psychological readiness to return to sports practice and risk of recurrence: Case studies

Returning to sport after the sports injury is a difficult decision because it's multicausal and the fact that a rash decision can result in numerous negative consequences. Given the importance of psychological variables for the correct rehabilitation of the injured athlete and his or her optimal return to sports practice, there seems to be little information on this subject. In this sense, the objective is to determine the relationship between the subjective psychological disposition of the athlete in the process of Return to Play (RTP) with the type of mood profile and his mental health. This is based on the fact that each athlete evaluates his or her recovery differently and has different levels of anxiety, depression, and stress. For this purpose, four athletes participated in the study. Two males and two females from the sports of indoor soccer and soccer, who had just returned to sports after a moderate or severe injury. The average age was 24.25 years. Various measurements were taken after practices and after matches, to assess mood, psychological readiness, anxiety, stress, and depression. The results confirm Morgan's iceberg profile and the influence that subjective psychological perceptions and assessed emotional states have on athletes' incorporation into their sports practice with a guarantee of success.

Revision anterior cruciate ligament reconstruction: Return to sports at a minimum 5-year follow-up

BACKGROUND

Between 43% and 75% of patients who undergo primary anterior cruciate ligament (ACL) surgery return to sport activity. However, after a revision ACL reconstruction (ACLR) the rate of return to sports is variable. A few publications have reported returns to sports incidence between 56% to 100% after revision ACLR.

AIM

To determine return to sports and functional outcomes after a single-stage revision ACLR with a 5-year minimum follow-up at a single institution.

METHODS

All patients operated between 2010 and 2016 with a minimum 5 years of follow-up were included. Type of sport, intensity, frequency, expectation, time to return to sport and failure rate were recorded. Lysholm, Tegner and International Knee Documentation Committee forms were evaluated prior to the first ACLR surgery, at 6 mo after primary surgery and after revision ACLR at 5 years minimum of follow-up. Objective stability was tested with the knee arthrometer test (KT-1000 knee arthrometer, Medmetric Corp).

RESULTS

A total of 41 patients who underwent revision ACLR during that period of time were contacted and available for follow-up. Median patient age at time of revision was 29 years old [interquartile range (IQR): 24.0-36.0], and 39 (95.0%) were male. The median time from revision procedure to follow-up was 70 mo (IQR: 58.0-81.0). Regarding return to sports, 16 (39.0%) were at the same level compared to preinjury period, and 25 patients (61.0%) returned at a lower level. Sixty-three percent categorized the sport as very important and 37.0% as important. One patient (2.4%) failed with a recurrent ACL torn. Mean preoperative Lysholm and subjective International Knee Documentation Committee scores were 58.8 [standard deviation (SD) 16] and 50 (SD 11), respectively. At follow-up, mean Lysholm and subjective International Knee Documentation Committee scores were 89 (SD 8) and 82 (SD 9) (P = 0.0001). Mean Tegner score prior to primary ACLR was 6.7 (SD 1.3), 5.1 (1.5 SD) prior to revision ACLR and 5.6 (1.6 SD) at follow-up (P = 0.0002). Overall, knee arthrometer test measurement showed an average of 6 mm (IQR: 4.0-6.0) side-to-side difference of displacement prior to revision ACLR and 3mm (IQR: 1.5-4.0) after revision.

CONCLUSION

Almost 40.0% of patients returned to preinjury sports level and 60.0% to a lower level. These may be useful when counseling a patient regarding sports expectations after a revision ACLR.