A dynamic test of lower extremity function following anterior cruciate ligament reconstruction and rehabilitation

Transphyseal ACL reconstruction and tenodesis in skeletally immature patients demonstrates encouraging clinical scores, without growth disturbance, excessive laxity or re-injury

Purpose

Paediatric patients demonstrate high re-rupture rates after anterior cruciate ligament reconstruction (ACLR), with numerous surgical techniques proposed to deal with this challenging cohort. This study investigated the early clinical outcomes, complications, return to sport (RTS) and re-rupture rates up until 2-years post-surgery in paediatric patients presenting with open growth plates undergoing transphyseal ACLR that was combined with an extra-articular tenodesis (LET).

Methods

Between October 2017 and September 2020, 20 skeletally immature patients were consecutively recruited and underwent transphyseal ACLR and LET. Patient reported outcome measures (PROMs), KT-1000 laxity, knee range of motion (ROM), maximal isokinetic knee torque and a 3-hop battery were assessed at 6-, 12- and 24-months. Limb Symmetry Indices (LSIs), RTS rates, complications, re-ruptures and re-operations were reviewed.

Results

All PROMs improved (p < 0.05). No change (p = 0.903) in laxity between limbs was seen, while 18 patients (90%) demonstrated normal (<3 mm) or near normal (3-5 mm) laxity differences. Peak knee flexion ROM improved over time (p = 0.028), while LSIs for knee extensor strength (p < 0.001), the single (p = 0.002) and triple crossover (p = 0.038) hop tests improved. At 24 months, 18 patients (90%) were participating in their pre-injury pivoting sport activities. No complications, growth disturbances, re-injuries or subsequent surgeries were observed.

Conclusions

Transphyseal ACLR combined with LET, undertaken in skeletally immature paediatric patients, demonstrated high scoring PROMs, physical performance and RTS overall, without evidence of growth disturbance or excessive graft laxity. No re-injuries have been observed at this time with ongoing review required in this high-risk cohort.

Two-Year Functional Outcomes of Nonsurgical Treatment in Concomitant Anterior Cruciate Ligament and Medial Collateral Ligament Injuries: A Case-Control Study

The anterior cruciate ligament (ACL) is a common knee injury in high-intensity sports, which can cause early career loss in young athletes. Concomitant damage to other knee stabilizers may occur, such as the medial collateral ligament (MCL). Recent studies have shown that knee stability can increase without surgical intervention in patients with ACL and MCL injuries. Regarding the importance of functional tests in return to exercise prediction, this study aims to measure nonsurgical approach's long-term outcome for concomitant ACL and MCL injuries with a focus on functional tests. This is a case-control study with a 2-year follow-up. The case group consisted of patients who had provided written consent and completed their 2-year follow-up, and the control group was made up of healthy people who did not have any knee medical conditions and were matched by age, gender, and activity level. Physical examinations, Tegner and International Knee Documentation Committee questionnaires, and knee magnetic resonance imaging were conducted, and functional performance tests were performed after a 10-minute warm-up. Lody's index (the ratio of injured-to-uninjured knee results) was calculated. The data were analyzed using independent t-test, one-way analysis of variance, chi-squared test, and Fisher's exact test. The study involved 11 patients in each concomitant ACL and MCL injury cases and healthy control groups with a mean age of 32.4 and 28 years, respectively. None of the patients reported knee instability symptoms in the 2-year follow-up. More than half of the patients continued their sports field without reinjury, with no significant difference in activity levels between case and control groups. The 6-meter hop test and single-leg hop test showed no significant difference between case and control groups (p-value: 0.326, 0.859), and no significant difference was observed in the three Carioca, cocontraction, and Shuttle tests in the 2-year follow-up. Functional tests in ACL and MCL injuries revealed normal outcomes, implying a nonsurgical approach for patients with proximal ACL tears, better knee stability, and no significant differences between the injured and control groups.

Evidence for isokinetic and functional testing in return to sport decisions following ACL surgery

The rupture and reconstruction of the anterior cruciate ligament (ACL) of the knee are associated with an increased risk of functional instability, a reduction in sports performance, and a higher risk of future additional injuries. Competitive athletes who participate in sports that require pivoting, cutting, and jumping are at particularly high risk for ACL rupture. The return to sport progression continuum after surgery includes sports-specific rehabilitation, evaluation of strength and function, gradual participation in exercise training with progressively challenging activities in the field of play, participation in sports at a lower level, and finally a return to preinjury-level sports competition. This narrative review evaluates the evidence that supports the use of quadriceps and hamstrings isokinetic strength testing and sports-specific functional skills assessments to evaluate progress with rehabilitation after ACL surgery. Strength evaluations, hop tests, agility tests, and the limb symmetry index are described, as well as the associations of quadriceps and hamstrings muscle strength and functional test results with successful return to sports and the risk of ACL graft rupture and contralateral knee injuries. Suggestions for future research directions are presented including the importance of presurgery testing, standardization of test batteries, and comparison of test results with normative data.

ACL Return to Sport Testing: It's Time to Step up Our Game

Patients and physicians have long looked to physical therapists to help determine an athlete's readiness to return to sport (RTS) following anterior cruciate ligament reconstruction (ACLR). This is a complex decision that must take into account biological healing, joint stability, functional performance, and psychological readiness. Considering that the vast majority of medical professionals use time as the sole determinant of an athlete's readiness, and few are using performance-based criteria, it appears as though our profession is failing to capture the necessary information to make this weighty recommendation. The time is now to take a hard look at current practice patterns with RTS testing and push the envelope forward. The purpose of this clinical commentary is challenge our failing status quo by disseminating a robust model for RTS testing that incorporates temporal and criterion-based factors, as well as intrinsic and extrinsic data.

LEVEL OF EVIDENCE

5.

Lower extremity muscle contributions to ACL loading during a stop-jump task

Landing is considered a high-risk movement, especially landings from a stop-jump task, as they are often associated with lower extremity injuries, such as anterior cruciate ligament injuries (ACL). Females demonstrate lower extremity landing mechanics that often place them at a larger risk of injury compared to their male counterparts. While efforts have been made to understand lower extremity mechanics during stop-jump landings, little is known regarding the musculature function during these tasks and how they may influence ACL loading. Understanding lower extremity muscle contributions to ACL loading (F_ACL) may give insight to improving injury prevention protocols. Ten healthy, recreationally active females completed five trials of an unanticipated stop-jump task. Right leg kinematics, kinetics, and electromyography data were collected with three-dimensional motion capture, force plates, and electromyography sensors, respectively. Modified musculoskeletal models were scaled based on participant-specific anthropometrics, and muscle forces were obtained using static optimization. An induced acceleration analysis combined with a previously established mathematical ACL loading model was used to calculate lower extremity muscle contribution to F_ACL. The vastus lateralis, vastus intermedius, vastus medials, biceps femoris long head, semimembranosus, and soleus were found to be the primary contributors to F_ACL, with the vastus lateralis being the largest contributor. These data suggest that muscles traditionally known as ACL unloaders may in certain conditions load the ACL. These results also suggest that future injury prevention protocols should target muscles specifically to mitigate the influence the vastus lateralis has on ACL loading.

A longitudinal investigation of landing biomechanics following anterior cruciate ligament reconstruction

OBJECTIVE

Abnormal movement patterns have been shown during landing in patients who have undergone anterior cruciate ligament (ACL) reconstruction surgery. The purpose of this study was to investigate landing biomechanics over time in this patient group to determine whether asymmetry between limbs reduced with time and after a return to physical activity.

DESIGN

Prospective longitudinal study.

SETTING

Biomechanics laboratory.

PARTICIPANTS

Fourteen patients who had undergone ACL reconstruction surgery.

MAIN OUTCOME MEASURE

Single limb landing assessments were made at two time points; within the first year (mean of 10 months) and at 3 years (after patients had returned to sport) following ACL reconstruction. Three-dimensional motion analysis was used to record kinematic and kinetic variables, which were compared across time and limb using ANOVA models.

RESULTS

Most biomechanical variables showed little change over time except for the external knee adduction moment at the operated knee, which increased (effect size d = 0.5), but remained less than the contralateral side. In the sagittal plane, asymmetrical landing patterns were seen at both assessments. Patients landed with reduced knee flexion angles (effect size range 0.76-0.9) and moments (effect size range 0.56-0.9) compared to the uninjured limb and made compensations for this by increasing the hip flexion moment (effect size range d = 0.6-0.75).

CONCLUSIONS

Asymmetrical landing biomechanics persisted at three years after ACL reconstruction in athletes who returned to sporting activity. Long term implications of controlling the landing by increasing the hip moment are unknown and require further investigation.

Hop Performance After Return to Sport in Anterior Cruciate Ligament-Reconstructed Gaelic Football and Hurling Athletes

PURPOSE

Anterior cruciate ligament (ACL) injuries are among the most severe injuries in the Gaelic Athletic Association. Hop tests measure functional performance after ACL reconstruction as they replicate the key requirements for a match situation. However, research examining functional recovery of ACL-reconstructed Gaelic athletes is lacking. The objective of this study is to determine if athletes restore normal hop symmetry after ACL reconstruction and to examine if bilateral deficiencies persist in hop performance following return to sport.

METHODS

A cross-sectional design was used to evaluate hop performance of 30 ACL-reconstructed Gaelic athletes who had returned to competition and 30 uninjured controls in a battery of hop tests including a single, 6-m, triple, and triple-crossover hop test.

RESULTS

In each test, the mean symmetry score of the ACL reconstruction group was above the cutoff for normal performance of 90% adopted by this study (98%, 99%, 97%, and 99% for the single, 6-m, triple, and triple-crossover hop, respectively). No significant differences in absolute hop scores emerged between involved and control limbs, with the exception of the single-hop test where healthy dominant limbs hopped significantly further than ACL-reconstructed dominant limbs (P = .02). No significant deficits were identified on the noninvolved side.

CONCLUSIONS

The majority of ACL-reconstructed Gaelic athletes demonstrate normal levels of hop symmetry after returning to competition. Suboptimal hop performance can persist on the involved side compared with control limbs. Targeted rehabilitation may be warranted after returning to competition to restore performance to levels of healthy uninjured athletes.

Tegner level is predictive for successful return to sport 2 years after anterior cruciate ligament reconstruction

PURPOSE

For a successful return to sport (RTS) after an anterior cruciate ligament reconstruction (ACLR), patients are recommended to attend a comprehensive rehabilitation program, followed by an RTS assessment, that is a combination of tests. The purpose of this study was to predict a successful return to sport using the results of the RTS assessment and self-reported questionnaires at minimum 2 years after ACLR.

METHODS

A total of 123 consecutive ACLR patients undertook an intensive rehabilitation program followed by a comprehensive RTS assessment that included an established combination of balance and strength tests, the ACL-return to sport after Injury scale (ACL-RSI) questionnaire and a KT1000 laximetry test. Preinjury and expected Tegner and Lysholm were collected at baseline, at RTS and prospectively collected at minimum 2-year follow-up. The patients were asked if they returned to their previous sport and at which level. All variables were included in a regression analysis predicting a successful return to previous sport, return to the same level of sport as well as the Tegner level at 2 years.

RESULTS

Sixty-two patients (50%) returned to their previous sport by the 2-year follow-up, without a difference in preinjury Tegner between these two groups (n.s.). Expected preoperative Tegner was the only significant predictor of a successful return to previous sport (p = 0.042; OR 1.300, 95% CI 1.010-1.672). Out of the 62 patients returning to their previous sport, 38 (61%) reported to be on the same or higher level. The only predictive variable for returning to the same level was the higher preinjury Tegner level (p = 0.048; OR 1.522). Multivariate regression analysis of Tegner level at 2 years found younger age to be the only predictive value. From the RTS assessment tests, the ACL-RSI questionnaire and the posterolateral balance test were predictive variables for Tegner at 2-year follow-up, albeit in the univariate regression analysis.

CONCLUSIONS

Preoperative Tegner and expected Tegner level collected prior to an ACL reconstruction can aid in the objective prediction of patients' return to sport after 2 years. High-level athletes are more likely to return to their previous sport and to the previous level. Younger patients achieve a higher Tegner level at 2 years.

LEVEL OF EVIDENCE

Level III study.

Patellofemoral Joint Loading During Single-Leg Hopping Exercises

CONTEXT

Single-leg hopping is used to assess a dynamic knee stability. Patellofemoral pain is often experienced during these exercises, and different cadences of jumping are often used in rehabilitation for those with patellofemoral pain. No studies to date have examined patellofemoral joint loading during single-leg hopping exercise with different hopping cadences.

OBJECTIVE

To determine if single-leg hopping at 2 different cadences (50 and 100 hops per minute [HPM]) leads to a significant difference in patellofemoral joint loading variables.

SETTING

University research laboratory.

PARTICIPANTS

Twenty-five healthy college-aged females (age 22.3 [1.8] y, height 171.4 [6.3] cm, weight 67.4 [9.5] kg, Tegner Activity Scale 4.75 [1.75]) participated.

MAIN OUTCOME MEASURES

Three-dimensional kinematic and kinetic data were measured using a 15-camera motion capture system and force platform. Static optimization was used to calculate muscle forces and then used in a musculoskeletal model to determine patellofemoral joint stress (PFJS), patellofemoral joint reaction force (PFJRF), quadriceps force (QF), and PFJRF loading rate, during the first and last 50% of stance phase.

RESULTS

Greater maximal PFJRF occurred at 100 HPM, whereas greater PFJRF loading rate occurred at 50 HPM. However, overall peak QF and peak PFJS were not different between the 2 cadences. At 50 HPM, there was greater PFJS, PFJRF, peak PFJRF loading rate, and peak QF during the first 50% of stance when compared with the last 50%.

CONCLUSION

Training at 50 HPM may reduce PFJRF and PFJRF loading rate, but not PFJS or QF. Patellofemoral joint loading variables had significantly higher values during the first half of the stance phase at the 50 HPM cadence. This may be important with training individuals with patellofemoral pain.

Association Between Isokinetic Knee Strength and Perceived Function and Patient Satisfaction With Sports and Recreational Ability After Matrix-Induced Autologous Chondrocyte Implantation

Background:

Returning to a sound level of activity after matrix-induced autologous chondrocyte implantation (MACI) is important to patients. Evaluating the patient’s level of satisfaction with his or her sports and recreational ability is critical.

Purpose:

To investigate (1) satisfaction with sports and recreational ability after MACI and (2) the role that knee strength plays in self-reported knee function and satisfaction.

Study Design:

Case-control study; Level of evidence, 3.

Methods:

Isokinetic knee strength was assessed in 97 patients at 1, 2, and 5 years after MACI to calculate hamstrings-quadriceps ratios and peak knee extensor and flexor torque limb symmetry indices (LSIs). The Sports and Recreation subscale of the Knee injury and Osteoarthritis Outcome Score (KOOS Sports/Rec) was completed. A satisfaction scale was used to evaluate how satisfied the patients were with their ability to return to recreational activities and their ability to participate in sport. Associations between knee strength LSI, KOOS Sports/Rec, and satisfaction with recreational and sporting activities were assessed through use of multivariable linear and logistic regression, with adjustment for confounders. Mediation analysis was conducted to assess the extent to which self-reported knee function mediated associations between strength LSI and satisfaction.

Results:

Satisfaction with the ability to return to recreational activities was achieved in 82.4%, 85.6%, and 85.9% of patients at 1, 2, and 5 years, respectively, and satisfaction with sports participation was achieved in 55.7%, 73.2%, and 68.5% of patients at 1, 2, and 5 years, respectively. Knee extension torque LSIs were associated with KOOS Sports/Rec after adjustment for confounders over 1, 2, and 5 years (5-year regression coefficient, 6.0 points; 95% CI, 1.4-10.7; P = .012). KOOS Sports/Rec was associated with the likelihood of being satisfied at all time points (recreation: 5-year adjusted odds ratio [OR], 2.26; 95% CI, 1.48-3.46; P < .001; and sports: 5-year adjusted OR, 1.98; 95% CI, 1.47-2.68; P < .001). In a multivariable mediation model, the knee extension torque LSI was associated with satisfaction directly (standardized coefficient, 0.16; 95% CI, 0.03-0.28; P = .017) and indirectly via KOOS Sports/Rec (standardized coefficient, 0.19; 95% CI, 0.01-0.38; P = .027), the latter representing 55% of the total association of knee extension torque LSI with satisfaction.

Conclusion:

Knee extensor symmetry was associated with satisfaction in recreational and sporting ability, both directly and indirectly, via self-reported sports and recreation–related knee function. Restoring strength deficits after MACI is important for achieving optimal outcomes.

Relationship Between Isokinetic Muscle Strength and Functional Tests in Chronic Ankle Instability

Isokinetic muscle strength measurements and functional tests are usually performed to evaluate ankle condition in chronic ankle instability (CAI), yet there is no clear demonstration of the relationship between isokinetic muscle strength and functional tests. The objective of this study was to evaluate the relationship between isokinetic muscle strength and functional tests in CAI. Between April 2014 and August 2016, 103 patients with unilateral CAI were studied. Single-leg balance, single-heel raise, and single-leg squat tests were performed for static balancing assessment. Single-leg hop, double-leg jump, and sidestep tests were performed for dynamic balancing assessment. The isokinetic muscle strength of both ankles was measured using a dynamometer. The involved ankle showed lower muscle strength in inversion than the uninvolved ankle, while eversion, dorsiflexion, and plantarflexion muscle strength had no significant differences between ankles. There were significant correlations between the isokinetic muscle strength of inversion and the single-leg balance test, single-heel raise test, and sidestep test (Pearson's r; 0.246, 0.514, and 0.229 at 30°/second; 0.288, 0.473, and 0.239 at 180°/second, respectively). The single leg balance, single heel raise, and sidestep tests are useful to assess not only ankle functional performance but also isokinetic muscle strength. Among these tests, the single heel raise test was the most reliable test to reflect muscle strength deficiency in CAI.

Task but not arm restriction influences lower extremity joint mechanics during bilateral landings

Box and jump landing tasks are commonly used to study lower extremity injury mechanisms, such as anterior cruciate ligament (ACL) injuries. Arm restriction during these tasks is typically determined via researcher preference. Therefore, the purpose of this study was to compare three-dimensional lower extremity kinematics and kinetics during bilateral box and jump landings, and to determine the effects of arm restriction. Twenty-eight participants (14 males, 14 females) completed three bilateral landings tasks: box landings with arms unrestricted (BLA), box landings with arms restricted against the trunk (BLNA) and jump landings (JL). Right leg joint kinematics and kinetics were collected and compared between landing tasks. No statistically significant differences were found between BLA and BLNA, therefore arm restriction did not appear to influence lower extremity variables during bilateral box landings. However, specific injury-related variables, such as peak knee adduction moment differed between box and jump landings (BLNA: 0.31 ± 0.3 Nm/(kg·m)); JL: 0.45 ± 0.3 Nm/(kg·m); p = 0.020). Our results suggest that based on study purpose, careful consideration is needed when determining what bilateral landing task to choose during data collection.

Unilateral Quadriceps Strengthening With Disinhibitory Cryotherapy and Quadriceps Symmetry After Anterior Cruciate Ligament Reconstruction

CONTEXT

  The effect of unilateral cryotherapy-facilitated rehabilitation exercise on involved-limb quadriceps function and limb symmetry in individuals with quadriceps dysfunction after anterior cruciate ligament reconstruction (ACLR) remains unclear.

OBJECTIVE

  To measure the effect of a 2-week unilateral cryotherapy-facilitated quadriceps-strengthening program on knee-extension strength and quadriceps central activation ratio (CAR) in participants with ACLR.

DESIGN

  Controlled laboratory study.

SETTING

  Laboratory.

PATIENTS OR OTHER PARTICIPANTS

  A total of 10 volunteers with unilateral ACLR (1 man, 9 women; age = 21.0 ± 2.8 years, height = 164.6 ± 5.0 cm, mass = 64.0 ± 6.1 kg, body mass index = 23.7 ± 2.7 kg/m²) and 10 healthy volunteers serving as control participants (1 man, 9 women; age = 20.8 ± 2.5 years, height = 169.1 ± 6.2 cm, mass = 61.1 ± 6.4 kg, body mass index = 21.4 ± 2.3 kg/m²) participated.

INTERVENTION(S)

  Participants with ACLR completed a 2-week unilateral cryotherapy-facilitated quadriceps-strengthening intervention.

MAIN OUTCOME MEASURE(S)

  Bilateral normalized knee-extension maximal voluntary isometric contraction (MVIC) torque (Nm/kg) and quadriceps CAR (%) were assessed preintervention and postintervention. Limb symmetry index (LSI) was calculated at preintervention and postintervention testing. Preintervention between-groups differences in unilateral quadriceps function and LSI were evaluated using independent-samples t tests. Preintervention-to-postintervention differences in quadriceps function were evaluated using paired-samples t tests. Cohen d effect sizes (95% confidence interval [CI]) were calculated for each comparison.

RESULTS

  Preintervention between-groups comparisons revealed less knee-extension MVIC torque and quadriceps CAR for the ACLR limb (MVIC: P = .01, Cohen d = -1.31 [95% CI = -2.28, -0.34]; CAR: P = .004, Cohen d = -1.48 [95% CI = -2.47, -0.49]) and uninvolved limb (MVIC: P = .03, Cohen d = -1.05 [95% CI = -1.99, -0.11]; CAR: P = .01, Cohen d = -1.27 [95% CI = -2.23, -0.31]) but not for the LSI (MVIC: P = .46, Cohen d = -0.34 [95% CI = -1.22, 0.54]; CAR: P = .60, Cohen d = 0.24 [95% CI = -0.64, 1.12]). In the ACLR group, participants had improved knee-extension MVIC torque in the involved limb ( P = .04, Cohen d = 0.32 [95% CI = -0.56, 1.20]) and uninvolved limb ( P = .03, Cohen d = 0.29 [95% CI = -0.59, 1.17]); however, the improvement in quadriceps CAR was limited to the involved limb ( P = .02, Cohen d = 1.16 [95% CI = 0.21, 2.11]). We observed no change in the LSI with the intervention for knee-extension MVIC torque ( P = .74, Cohen d = 0.09 [95% CI = -0.79, 0.97]) or quadriceps CAR ( P = .61, Cohen d = 0.26 [95% CI = -0.62, 1.14]).

CONCLUSIONS

  Two weeks of cryotherapy-facilitated exercise may improve involved-limb quadriceps function while preserving between-limbs symmetry in patients with a history of ACLR.

Two-Year Outcomes of a Randomized Trial Investigating a 6-Week Return to Full Weightbearing After Matrix-Induced Autologous Chondrocyte Implantation

BACKGROUND

Matrix-induced autologous chondrocyte implantation (MACI) has demonstrated encouraging outcomes in treating patients with knee cartilage defects. Postoperatively, the time required to attain full weightbearing (WB) remains conservative.

HYPOTHESIS

We hypothesized that patients would have no significant clinical or radiological differences or graft complications after an 8-week or 6-week return to full WB after MACI.

STUDY DESIGN

Randomized controlled trial; Level of evidence, 1.

METHODS

A total of 37 knees (n = 35 patients) were randomly allocated to either an 8-week return to full WB that we considered current best practice based on the existing literature (CR group; n = 19 knees) or an accelerated 6-week WB approach (AR group; n = 18 knees). Patients were evaluated preoperatively and at 1, 2, 3, 6, 12, and 24 months after surgery, using the Knee Injury and Osteoarthritis Outcome Score, 36-Item Short Form Health Survey, visual analog pain scale, 6-minute walk test, and active knee range of motion. Isokinetic dynamometry was used to assess peak knee extension and flexion strength and limb symmetry indices (LSIs) between the operated and nonoperated limbs. Magnetic resonance imaging (MRI) was undertaken to evaluate the quality and quantity of repair tissue as well as to calculate an MRI composite score.

RESULTS

Significant improvements ( P < .05) were observed in all subjective scores, active knee flexion and extension, 6-minute capacity, peak knee extensor torque in the operated limb, and knee extensor LSI, although no group differences existed. Although knee flexor LSIs were above 100% for both groups at 12 and 24 months after surgery, LSIs for knee extensor torque at 24 months were 93.7% and 87.5% for the AR and CR groups, respectively. The MRI composite score and pertinent graft parameters significantly improved over time ( P < .05), with some superior in the AR group at 24 months. All patients in the AR group (100%) demonstrated good to excellent infill at 24 months, compared with 83% of patients in the CR group. Two cases of graft failure were observed, both in the CR group. At 24 months, 83% of patients in the CR group and 88% in the AR group were satisfied with the results of their MACI surgery.

CONCLUSION

Patients in the AR group who reduced the length of time spent ambulating on crutches produced comparable outcomes up to 24 months, without compromising graft integrity.

A Prospective Clinical and Radiological Evaluation at 5 Years After Arthroscopic Matrix-Induced Autologous Chondrocyte Implantation

BACKGROUND

While midterm outcomes after matrix-induced autologous chondrocyte implantation (MACI) are encouraging, the procedure permits an arthroscopic approach that may reduce the morbidity of arthrotomy and permit accelerated rehabilitation.

HYPOTHESIS

A significant improvement in clinical and radiological outcomes after arthroscopic MACI will exist through to 5 years after surgery.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

We prospectively evaluated the first 31 patients (15 male, 16 female) who underwent MACI via arthroscopic surgery to address symptomatic tibiofemoral chondral lesions. MACI was followed by a structured rehabilitation program in all patients. Clinical scores were administered preoperatively and at 3 and 6 months as well as 1, 2, and 5 years after surgery. These included the Knee injury and Osteoarthritis Outcome Score (KOOS), Lysholm knee scale (LKS), Tegner activity scale (TAS), visual analog scale for pain, Short Form-36 Health Survey (SF-36), active knee motion, and 6-minute walk test. Isokinetic dynamometry was used to assess peak knee extension and flexion strength and limb symmetry indices (LSIs) between the operated and nonoperated limbs. High-resolution magnetic resonance imaging (MRI) was performed at 3 months and at 1, 2, and 5 years postoperatively to evaluate graft repair as well as calculate the MRI composite score.

RESULTS

There was a significant improvement ( P < .05) in all KOOS subscale scores, LKS and TAS scores, the SF-36 physical component score, pain frequency and severity, active knee flexion and extension, and 6-minute walk distance. Isokinetic knee extension strength significantly improved, and all knee extension and flexion LSIs were above 90% (apart from peak knee extension strength at 1 year). At 5 years, 93% of patients were satisfied with MACI to relieve their pain, 90% were satisfied with improving their ability to undertake daily activities, and 80% were satisfied with the improvement in participating in sport. Graft infill ( P = .033) and the MRI composite score ( P = .028) significantly improved over time, with 90% of patients demonstrating good to excellent tissue infill at 5 years. There were 2 graft failures at 5 years after surgery.

CONCLUSION

The arthroscopically performed MACI technique demonstrated good clinical and radiological outcomes up to 5 years, with high levels of patient satisfaction.

Using an accelerometer and the step-up-and-over test to evaluate the knee function of patients with anterior cruciate ligament reconstruction

BACKGROUND

Evaluating the dynamic knee function of patients after anterior cruciate ligament reconstruction is a challenge. A variety of objective tests have been developed but for various reasons few are regularly used in the clinic. It may be practical to perform the step-up-and-over test with an accelerometer.

METHODS

A control group (N=26) and an experimental group with a reconstructed anterior cruciate ligament (N=25) completed questionnaires quantifying subjective knee function and fear of re-injury and then completed the step-up-and-over test.

FINDINGS

Results showed that the experimental group performed differently than the control group for the step-up-and-over test's Lift Symmetry and Impact Symmetry (P<0.05) and performance on these measures was related to the participant's subjective knee function (ρ=-0.46, P<0.01; ρ=-0.33, P<0.05, respectively). Supplemental results for individual leg performance and the patient's fear of re-injury are also reported and discussed.

INTERPRETATION

Performance on the step-up-and-over test is different for participants with anterior cruciate ligament reconstruction than for those with intact anterior cruciate ligaments, and that performance is related to one's opinion of their knee's function.

The Importance of Patient Sex in the Outcomes of Anterior Cruciate Ligament Reconstructions: A Systematic Review and Meta-analysis

BACKGROUND

One of the well-studied epidemiological phenomena of anterior cruciate ligament (ACL) injuries is the 2- to 9-fold increase in the relative risk of ACL rupture in female athletes compared with male athletes. However, the influence of patient sex on the outcome after ACL reconstruction remains unclear, with some authors reporting inferior outcomes in females and others noting no significant difference.

PURPOSE

To provide a comprehensive systematic review and meta-analysis to examine the possible association between patient sex and the subjective and objective outcomes after ACL reconstruction.

METHODS

This study was conducted according to PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. All studies that reported clinical outcomes after ACL reconstruction in males and females independently were included in the review. A quantitative random-effects meta-analysis was performed to compare outcomes between sexes. For outcomes with considerable heterogeneity, meta-regression was used to identify potential moderators. Articles were evaluated qualitatively when quantitative data were not reported.

RESULTS

A total of 135 publications were included in the review. Females had inferior outcomes in instrumented laxity (standardized mean difference [SMD], 0.24; 95% CI, 0.11-0.37), revision rate (relative risk [RR], 1.15; 95% CI, 1.02-1.28), Lysholm score (SMD, -0.33; 95% CI, -0.55 to -0.11), Tegner activity scale (SMD, -0.37; 95% CI, -0.49 to -0.24), and incidence of not returning to sports (RR, 1.12; 95% CI, 1.04-1.21), all of which were statistically significant. Other outcomes were comparable between sexes, including anterior drawer test, Lachman test, pivot-shift test, timed single-legged hop test, single-legged hop test, quadriceps testing, hamstring testing, extension loss, flexion loss, development of cyclops lesion, and International Knee Documentation Committee (IKDC) knee examination score. Females and males were equally likely to develop anterior knee pain and osteoarthritis after ACL reconstruction. The graft rupture and graft failure rates did not differ significantly between sexes.

CONCLUSION

There were comparable or inferior results for females compared with males in all outcomes analyzed. No statistically significant sex difference was identified in most of the objective parameters. However, subjective and functional outcomes, including Lysholm score, Tegner activity scale, and ability to return to sports, have been shown to be poorer in females.

A conceptual framework for a sports knee injury performance profile (SKIPP) and return to activity criteria (RTAC)

Injuries to the knee, including intra-articular fractures, ligamentous ruptures, and meniscal and articular cartilage lesions, are commonplace within sports. Despite advancements in surgical techniques and enhanced rehabilitation, athletes returning to cutting, pivoting, and jumping sports after a knee injury are at greater risk of sustaining a second injury. The clinical utility of objective criteria presents a decision-making challenge to ensure athletes are fully rehabilitated and safe to return to sport. A system centered on specific indicators that can be used to develop a comprehensive profile to monitor rehabilitation progression and to establish return to activity criteria is recommended to clear athletes to begin a progressive and systematic approach to activities and sports. Integration of a sports knee injury performance profile with return to activity criteria can guide clinicians in facilitating an athlete's safe return to sport, prevention of subsequent injury, and life-long knee joint health.

Neuromuscular Evaluation With Single-Leg Squat Test at 6 Months After Anterior Cruciate Ligament Reconstruction

Background:

Criteria for return to unrestricted activity after anterior cruciate ligament (ACL) reconstruction varies, with some using time after surgery as the sole criterion—most often at 6 months. Patients may have residual neuromuscular deficits, which may increase the risk of ACL injury. A single-leg squat test (SLST) can dynamically assess for many of these deficits prior to return to unrestricted activity.

Hypothesis:

A significant number of patients will continue to exhibit neuromuscular deficits with SLST at 6 months after ACL reconstruction.

Study Design:

Cross-sectional study; Level of evidence, 3.

Methods:

Patients using a standardized accelerated rehabilitation protocol at their 6-month follow-up after primary ACL reconstruction were enrolled. Evaluation included bilateral SLST, single-leg hop distance, hip abduction strength, and the subjective International Knee Documentation Committee (IKDC) score.

Results:

Thirty-three patients were enrolled. Poor performance of the operative leg SLST was found in 15 of 33 patients (45%). Of those 15 patients, 7 (45%) had concomitant poor performance of the nonoperative leg compared with 2 of 18 patients (11%) in those who demonstrated good performance in the operative leg. The poor performers were significantly older (33.6 years) than the good performers (24.2 years) (P = .007). Those with poor performance demonstrated decreased hip abduction strength (17.6 kg operative leg vs 20.5 kg nonoperative leg) (P = .024), decreased single-leg hop distance (83.3 cm operative leg vs 112.3 cm nonoperative leg) (P = .036), and lower IKDC scores (67.9 vs 82.3) (P = .001).

Conclusion:

Nearly half of patients demonstrated persistent neuromuscular deficits on SLST at 6 months, which is when many patients return to unrestricted activity. Those with poor performance were of a significantly older age, decreased hip abduction strength, decreased single-leg hop distance, and lower IKDC subjective scores.

Clinical Relevance:

The SLST can be used to identify neuromuscular risk factors for ACL rupture. Many patients at 6 months have persistent neuromuscular deficits on SLST. Caution should be used when using time alone to determine when patients can return to unrestricted activity.

Persistent neuromuscular and corticomotor quadriceps asymmetry after anterior cruciate ligament reconstruction

CONTEXT

Return to activity in the presence of quadriceps dysfunction may predispose individuals with anterior cruciate ligament reconstruction (ACLR) to long-term joint degeneration. Asymmetry may manifest during movement and result in altered knee-joint-loading patterns; however, the underlying neurophysiologic mechanisms remain unclear.

OBJECTIVE

To compare limb symmetry of quadriceps neuromuscular function between participants with ACLR and participants serving as healthy controls.

DESIGN

Descriptive laboratory study.

SETTING

Research laboratory.

PATIENTS OR OTHER PARTICIPANTS

A total of 22 individuals with ACLR (12 men, 10 women) and 24 individuals serving as healthy controls (12 men, 12 women).

MAIN OUTCOME MEASURE(S)

Normalized knee-extension maximal voluntary isometric contraction (MVIC) torque (Nm/kg), quadriceps central activation ratio (CAR) (%), quadriceps motor-neuron-pool excitability (Hoffmann reflex to motor wave ratio), and quadriceps active motor threshold (AMT) (% 2.0 T) were measured bilaterally and used to calculate limb symmetry indices for comparison between groups. We used analyses of variance to compare quadriceps Hoffmann reflex to motor wave ratio, normalized knee-extension MVIC torque, quadriceps CAR, and quadriceps AMT between groups and limbs.

RESULTS

The ACLR group exhibited greater asymmetry in knee-extension MVIC torque (ACLR group = 0.85 ± 0.21, healthy group = 0.97 ± 0.14; t44 = 2.26, P = .03), quadriceps CAR (ACLR group = 0.94 ± 0.11, healthy group = 1.00 ± 0.08; t44 = 2.22, P = .04), and quadriceps AMT (ACLR group = 1.13 ± 0.18, healthy group = 1.02 ± 0.11; t34 = -2.46, P = .04) than the healthy control group.

CONCLUSIONS

Asymmetries in measures of quadriceps function and cortical excitability were present in patients with ACLR. Asymmetry in quadriceps strength, activation, and cortical excitability persisted in individuals with ACLR beyond return to recreational activity. Measuring the magnitude of asymmetry after ACLR represents an important step in understanding long-term reductions in self-reported function and increased rate of subsequent joint injury in otherwise healthy, active individuals after ACLR.

Clinical rehabilitation guidelines for matrix-induced autologous chondrocyte implantation on the tibiofemoral joint

Autologous chondrocyte implantation (ACI) has become an established technique for the repair of full-thickness chondral defects in the knee. Matrix-induced ACI (MACI) is the third and current generation of this surgical technique, and, while postoperative rehabilitation following MACI aims to restore normal function in each patient as quickly as possible by facilitating a healing response without overloading the repair site, current published guidelines appear conservative, varied, potentially outdated, and often based on earlier ACI surgical techniques. This article reviews the existing evidence-based literature pertaining to cell loading and postoperative rehabilitation following generations of ACI. Based on this information, in combination with the technical benefits provided by third-generation MACI in comparison to its surgical predecessors, we present a rehabilitation protocol for patients undergoing MACI in the tibiofemoral joint that has now been implemented for several years by our institution in patients with MACI, with good clinical outcomes.

Concurrent assessments of lower limb loading patterns, mechanical muscle strength and functional performance in ACL-patients--a cross-sectional study

BACKGROUND

Full recovery in muscle strength and functional performance may not be achieved after ACL-injury.

AIM

The aim of this study is to investigate loading patterns during jumping, muscle function and functional performance in ACL-reconstructed patients and to investigate the origin of between-limb asymmetry by means of a 3-dimensional movement analysis. Design is cross-sectional.

METHODS

23 ACL-reconstructed men (27.2±7.5 years, BMI: 25.4±3.2) 27±7 month post-surgery and 25 matched controls (27.2±5.4 years, BMI: 24.1±1.8) were included. Participants performed (i) bilateral and (ii) unilateral counter movement jumps (CMJ). A 3-D movement analysis was performed by a six-camera Vicon MX-system. Subsequently, jump height (JH), knee joint range of motion (ROM), peak and mean sagittal knee moments were analyzed (iii) one-leg maximal jump for distance was performed, and (iv) maximal unilateral isometric knee extensor and flexor strength (MVC) were measured using stabilized dynamometry.

RESULTS

No in-between group differences in age or BMI were observed. CMJ: Between-limb asymmetry ratios for ROM differed (p<0.01) between patients and controls in both types of CMJ (96.1% vs. 102.6% and 87.0% vs. 99.9% in bilateral and single-leg CMJs, respectively). Jump for distance: Patients demonstrated greater (p<0.01) asymmetry for jump length (92.9% vs. 98.6%). MVC: Asymmetry in hamstring MVC was greater (p<0.001) for patients than controls (77.4% vs. 101.3%).

CONCLUSIONS

ACL-patients showed reduced function of the operated leg~2 years post ACL-reconstruction, especially for hamstring MVC. Hamstrings are important protagonists to the ACL, thus representing a potential risk factor for secondary ACL-rupture and/or osteoarthritis.

Variability in leg muscle power and hop performance after anterior cruciate ligament reconstruction

PURPOSE

The purpose of this prospective study was to describe the variability in leg muscle power and hop performance up to 2 years among patients following ACL reconstruction and specifically to illustrate the effects of various criteria for an acceptable level of muscle function.

METHODS

Eighty-two patients (56 men and 26 women)with a mean age of 28 years, who underwent ACL reconstruction using either hamstring tendons (n = 46) or a patellar tendon (n = 36), were assessed pre-operatively and 3, 6, 12 and 24 months post-surgery with a battery of three lower extremity muscle power tests and a battery of three hop tests.

RESULTS

Leg symmetry index (LSI) values at group level ranged between 73 and 100% at all follow-ups. When the tests were evaluated individually, patients reached an average LSI of ≥ 90% at 24 months. The success rate at 24 months for the muscle power test battery, that is,patients with an LSI of ≥ 90% in all three tests, was 48 and 44% for the hop test battery. The success rate at 24 months for both test batteries on all six muscle function tests was 22%. The criterion of an LSI of ≥ 80% resulted in 53% of the patients having an acceptable level on all six tests,while with a criterion of an LSI of ≥ 100%, none of the patients reached an acceptable level.

CONCLUSION

At group level and in single muscle function tests, the muscle function outcome 1 and 2 years after ACL reconstruction is satisfactory in the present study and on a par with the results presented in the literature. However,when using more demanding criteria for a successful muscle function outcome, using batteries of tests or increasing the acceptable LSI level from ≥ 90% to ≥ 95%or ≥ 100%, the results are considered to be poor. It is suggested that this should be taken into consideration when presenting results after ACL rehabilitation, deciding on the criteria for a safe return to sports, or designing rehabilitation programmes after ACL reconstruction.

LEVEL OF EVIDENCE

Prognostic prospective cohort study, Level I.

The ability of 4 single-limb hopping tests to detect functional performance deficits in individuals with functional ankle instability

STUDY DESIGN

Experimental laboratory testing using a cross-sectional design.

OBJECTIVES

To determine if functional performance deficits are present in individuals with functional ankle instability (FAI) in 4 single-limb hopping tests, including figure-of-8 hop, side hop, 6-meter crossover hop, and square hop.

BACKGROUND

Conflicting results exist regarding the presence of functional deficits in individuals with FAI. It is important to evaluate whether functional performance deficits are present in this population, as well as if subjective feelings of giving way can assist in identifying these deficits.

METHODS

Sixty college students volunteered for this study. Thirty participants with unilateral ankle instability were placed in the FAI group and 30 participants with no history of ankle injuries were placed in the control group. The FAI group was subsequently further divided to indicate those that reported giving way during the functional test (FAI-GW) and those that did not (FAI-NGW). Time to complete each test was recorded and the mean of 3 trials for each test were used for statistical analysis. To identify performance differences, we used 4 mixed-design 2-way (side-by-group) ANOVAs, 1 for each hop test. A Tukey post hoc test was completed on all significant findings.

RESULTS

We identified a significant side-by-group interaction for all 4 functional performance tests (P<.05). Specifically, for each functional performance test, the FAI limb performed significantly worse than the contralateral uninjured limb in the FAI-GW group. Additionally, the FAI limb in the FAI-GW group performed worse than the FAI limb in the FAI-NGW group, and the matched limb in the control group in 3 of the 4 functional performance tests.

CONCLUSION

We found that functional performance deficits were present in participants with FAI who also experienced instability during the test. This difference was identified when comparing the FAI limb to the contralateral uninjured limb as well as control participants. However, the performance deficits identified in this study were relatively small. Future research in this area is needed to further evaluate the clinical meaningfulness of these findings. Finally, we found that limb dominance did not affect performance.

Leg kinematics and kinetics in landing from a single-leg hop for distance. A comparison between dominant and non-dominant leg

BACKGROUND

Anterior cruciate ligament (ACL) deficiency can be a major problem for athletes and subsequent reconstruction of the ACL may be indicated if a conservative regimen has failed. After ACL reconstruction signs of abnormality in the use of the leg remain for a long time. It is expected that the landing after a single-leg hop for distance (horizontal hop) might give insight in the differences in kinematics and kinetics between uninjured legs and ACL-reconstructed legs. Before the ACL-reconstructed leg can be compared with the contralateral leg, knowledge of differences between legs of uninjured subjects is needed.

METHODS

Kinematic and kinetic variables of both legs were measured with an optoelectronic system and a force plate and calculated by inverse dynamics. The dominant leg (the leg with biggest horizontal hop distance) and the contralateral leg of nine uninjured subjects were compared.

FINDINGS

No significant differences were found in most of the kinematic and kinetic variables between dominant leg and contralateral leg of uninjured subjects. Only hop distance and hip extension angles differed significantly.

INTERPRETATION

This study suggests that there are no important differences between dominant leg and contralateral leg in healthy subjects. As a consequence, the uninvolved leg of ACL-reconstructed patients can be used as a reference. The observed variables of this study can be used as a reference of normal values and normal differences between legs in healthy subjects.

A test battery for evaluating hop performance in patients with an ACL injury and patients who have undergone ACL reconstruction

The purpose of this study was to develop a test battery of hop tests with high ability to discriminate (i.e. high test-retest reliability, sensitivity, specificity and accuracy) between the hop performance of the injured and the uninjured side in patients with an ACL injury and in patients who have undergone ACL reconstruction. Five hop tests were analysed: three maximum single hop tests and two hop tests while developing fatigue. Fifteen healthy subjects performed the five hop tests on three separate occasions in a test-retest design. Thirty patients, mean 11 months after an ACL injury and 35 patients, mean 6 months after ACL reconstruction were tested. ICC values ranged from 0.85 to 0.97 for the five hop tests, indicating that all the tests had high test-retest reliability. Sixty-seven percent to 100% of the healthy subjects had normal symmetry (i.e. <10% side-to-side difference) in the five hop tests. Abnormal symmetry in the five hop tests ranged from 43 to 77% for patients with an ACL injury and from 51 to 86% for patients who had undergone ACL reconstruction respectively. The three tests with the highest ability to discriminate hop performance were chosen for the test battery; they were the vertical jump, the hop for distance and the side hop. The test battery revealed a high level of sensitivity and accuracy in patients with an ACL injury (87 and 84%) and in patients who had undergone ACL reconstruction (91 and 88%), when at least one of the three tests was classified as abnormal. To summarise, the test battery consisting of both maximum single hop performances: the vertical jump and the hop for distance and hop performance while developing fatigue: the side hop, produced high test-retest reliability, sensitivity and accuracy. Further, the test battery produced higher values compared with any of the three hop tests individually revealing that only one out of ten patients had restored hop performance 11 months after an ACL injury and 6 months after ACL reconstruction. It is concluded that this test battery showed a high ability to discriminate between the hop performance of the injured and the uninjured side both in patients with an ACL injury and in patients who have undergone ACL reconstruction.

Improving the sensitivity of the hop index in patients with an ACL deficient knee by transforming the hop distance scores

Background

The one leg hop for distance is one of the most commonly employed functional tests utilized in the evaluation of the ACL deficient and reconstructed patient. While the reliability of the hop test scores has been well established, validity studies have revealed low sensitivity rates in detecting functional limitations using the hop index (the ratio or percentage of limb performance). However, the impact of the inherent limitations associated with the hop index have not been investigated to date. One specific limitation relates to the impact of the differences in the underlying hop distance scores. Therefore, this pilot study set out to determine: 1) the impact that between limb differences in hop distance has on the sensitivity of the hop index in detecting functional limitations and; 2) whether a logarithmic transformation of the underlying hop distance scores improves the sensitivity of the hop index.

Methods

A cross sectional design involving the evaluation of one leg hop for distance performance in a consecutive sample of 10 ACL deficient males with an isolated ACL tear awaiting reconstructive surgery and nine gender, age-matched controls.

Results

In the ACL deficient, the hop index was associated with the distance hopped on the non-injured limb (r = -0.66, p = 0.04) but not on the injured limb. Transformation (logarithmic) of the hop distance scores and re-calculation of the hop index using the transformed scores increased the sensitivity of the hop index in the detection of functional limitations from 20 to 60% and 50 to 70% using the normal limb symmetry reference norms of ≥ 85% and 90% respectively.

Conclusion

The distance hopped on the non-injured limb is a critical factor in detecting functional limitations using the hop index in patients with an ACL deficient knee. Logarithmic transformation of the hop distance scores minimizes the effect of the arithmetic differences between limbs however; the sensitivity of the hop index in detecting abnormal limb symmetry remains low.

Ability of a new hop test to determine functional deficits after anterior cruciate ligament reconstruction

The aim of this study was to investigate the ability of a new hop test to determine functional deficits after anterior cruciate ligament (ACL) reconstruction. The test consists of a pre-exhaustion exercise protocol combined with a single-leg hop. Nineteen male patients with ACL reconstruction (mean time after operation 11 months) who exhibited normal single-leg hop symmetry values (> or =90% compared with the non-involved extremity) were tested for one-repetition maximum (1 RM) strength of a knee-extension exercise. The patients then performed single-leg hops following a standardised pre-exhaustion exercise protocol, which consisted of unilateral weight machine knee-extensions until failure at 50% of 1 RM. Although no patients displayed abnormal hop symmetry when non-fatigued, 68% of the patients showed abnormal hop symmetry for the fatigued test condition. Sixty-three per cent exhibited 1 RM strength scores of below 90% of the non-involved leg. Eighty-four percent of the patients exhibited abnormal symmetry in at least one of the tests. Our findings indicate that patients are not fully rehabilitated 11 months after ACL reconstruction. It is concluded that the pre-exhaustion exercise protocol, combined with the single-leg hop test, improved testing sensitivity when evaluating lower-extremity function after ACL reconstruction. For a more comprehensive evaluation of lower-extremity function after ACL reconstruction, it is therefore suggested that functional testing should be performed both under non-fatigued and fatigued test conditions.

Neuromuscular dynamic restraint in women with anterior cruciate ligament injuries

The purpose of this study was to identify neuromuscular characteristics related to dynamic restraint in the knee. Observing compensatory changes to these characteristics in women with anterior cruciate ligament injuries provides important information for understanding functional knee stability, injury prevention, and performance. Twelve female subjects with anterior cruciate ligament injuries and 17 female control subjects participated in this study to assess electromyographic activity during landing from a hop and knee perturbation; hamstring muscle stiffness and flexibility; and isokinetic strength. Females with anterior cruciate ligament deficiencies had significantly increased preparatory muscle activity in the lateral hamstring before landing, but no differences in reactive muscle activity during landing or reflex latency after joint perturbation. Females with anterior cruciate ligament deficiencies had significantly less hamstring muscle stiffness and flexibility, but also had greater peak torque and torque development for knee flexion. Lower Lysholm scores were observed in females with anterior cruciate ligament deficiencies but no difference was found in functional performance of the single leg hop test. These neuromuscular characteristics provide a foundation for future research investigating injury prevention and rehabilitation techniques that maximize dynamic restraint through stiffness regulation and the timing of specific muscle activation strategies.

Landing adaptations after ACL reconstruction

PURPOSE

The purpose of this study was to determine whether fully rehabilitated ACL reconstructed (ACLr) recreational athletes utilize adapted lower-extremity joint kinematics and kinetics during a high-demand functional task.

METHODS

The kinematic and kinetic performance of 11 healthy and 11 hamstring ACLr recreational athletes were compared during a 60-cm vertical drop landing.

RESULTS

At initial ground contact, the ACLr group demonstrated greater hip extension and ankle plantarflexion compared with the healthy group. The peak vertical ground-reaction force was not different between groups, but the ACLr group delayed the time to its occurrence. The knee extensors provided the major energy absorption function for both groups; however, the ACLr group performed 37% more ankle plantarflexor work and 39% less hip extensor work compared with the healthy group.

CONCLUSIONS

The hamstring ACLr recreational athletes utilized an adapted landing strategy that employed the hip extensor muscles less and the ankle plantarflexor muscles more. The harvesting of the medial hamstring muscles for ACL reconstruction may contribute to the utilization of this protective landing strategy.

One-arm hop test: reliability and effects of arm dominance

STUDY DESIGN

Test-retest reliability analysis and 2-factor ANOVA contrast of athletic group and limb dominance.

OBJECTIVES

To determine the reliability of the one-arm hop test and the effects of upper-extremity dominance on test scores for 2 athletic groups.

BACKGROUND

Limited information is available regarding functional performance tests of the upper extremity that involve axial loading.

METHODS AND MEASURES

Thirteen male collegiate wrestlers (mean age, 20.3 +/- 1.6 years) and 13 male collegiate football players (mean age, 20.0 +/-1.7 years) without upper-extremity pathology participated in the study. Subjects were trained to perform the one-arm hop test, starting from a one-arm push-up position and then hopping as quickly as possible onto and off of a 10.2-cm platform 5 times. Subjects returned to the test site 1 to 2 days later and were timed for 2 trials of the one-arm hop test for each upper extremity.

RESULTS

Within-session ICC2,1 reliability values were 0.78 for the football players and 0.81 for the wrestlers. Mean absolute differences between trials were 0.64 seconds for the football players and 0.47 seconds for the wrestlers. Trial 2 performance times were significantly faster than trial 1 times for the wrestlers. Although performance time for the nondominant side was on average 4.4% slower than that of the dominant side, performance times for the dominant side were not significantly different from those of the nondominant upper extremities.

CONCLUSIONS

The results provide preliminary evidence that the one-arm hop test may be a reliable upper-extremity functional performance test with sufficient training of the subject. Uninjured upper-extremity performance for the one-arm hop test may be useful as a basis for comparing performance of an injured contralateral upper extremity.

Hop tests as predictors of dynamic knee stability

Single leg hop tests are commonly used as physical performance measures of function and are also commonly used to evaluate progress in knee rehabilitation programs, particularly for individuals recovering from anterior cruciate ligament injury or reconstructive surgery. While there is some evidence that hop tests may show promise as a predictive measure for identifying individuals who are at risk for recurrent dynamic instability, further work is needed to clearly define the role of hop test measurements for this purpose. The purposes of this clinical commentary are to review the research that has been done to establish hop tests as a physical performance measure of function, to discuss neuromuscular and biomechanical considerations related to hop performance and dynamic knee stability, to discuss existing evidence that supports the potential for hop tests as a predictor of dynamic knee stability, and to discuss considerations for future studies that are designed to more clearly define the role of hop tests in predicting dynamic knee stability.

Gait biomechanics are not normal after anterior cruciate ligament reconstruction and accelerated rehabilitation

PURPOSE

Accelerated rehabilitation for anterior cruciate ligament (ACL) injury and reconstruction surgery is designed to return injured people to athletic activities in approximately 6 months. The small amount of empirical data on this population suggests, however, that the torque at the knee joint may not return until 22 months after surgery during walking and even longer during running. Although the rehabilitation has ended and individuals have returned to preinjury activities, gait mechanics appear to be abnormal at the end of accelerated programs. The purpose of this study was to compare lower extremity joint kinematics, kinetics, and energetics between individuals having undergone ACL reconstruction and accelerated rehabilitation and healthy individuals.

METHODS

Eight ACL-injured and 22 healthy subjects were tested. Injured subjects were tested 3 wk and 6 months (the end of rehabilitation) after surgery. Ground reaction force and kinematic data were combined with inverse dynamics to predict sagittal plane joint torques and powers from which angular impulse and work were derived.

RESULTS

The difference in all kinematic variables between the two tests for the ACL group averaged 38% (all P < 0.05). The kinematics were not different between the ACL group after rehabilitation and healthy subjects. Angular impulses and work averaged 100% difference for all joints (all P < 0.05) between tests for the ACL group. After rehabilitation, the differences between injured and healthy groups in angular impulse and work at both the hip and knee remained large and averaged 52% (all P < 0.05).

CONCLUSIONS

Results indicated that after reconstruction surgery and accelerated rehabilitation for ACL injury, humans walk with normal kinematic patterns but continue to use altered joint torque and power patterns.