Early clinical and neuromuscular properties in patients with normal or sub-normal subjective knee function after anterior cruciate ligament reconstruction

The effects of blood flow restriction training on early muscle strength and mid-term knee function following anterior cruciate ligament reconstruction: a systematic review and meta-analysis

OBJECTIVE

Early restoration of muscle strength and knee joint function after anterior cruciate ligament reconstruction (ACLR) is a critical goal in the rehabilitation process. Blood flow restriction training (BFRT), a low-load training method, has gained attention in musculoskeletal rehabilitation in recent years, but its specific effects in ACLR rehabilitation remain unclear.

METHODS

Relevant literature up to December 20, 2024, was searched in the PubMed, Embase, Cochrane, and Web of Science databases, and study selection was performed according to PRISMA guidelines. Randomized controlled trials (RCTs) and quasi-RCTs comparing the effects of BFRT and traditional training in ACLR rehabilitation were included. Data on early muscle strength (ACSA and MVIC) and mid-term knee function (IKDC scores and isometric strength of knee extensors) were extracted. The quality of the studies was assessed using the Cochrane risk of bias tool, and statistical analyses were conducted using fixed-effect or random-effect models.

RESULTS

A total of 11 studies involving 276 patients were included, with 139 in the BFRT group and 137 in the control group. Meta-analysis showed no significant improvements in quadriceps ACSA (SMD = 0.82, 95% CI: -0.17 to 1.81, p = 0.10) or MVIC (SMD = 0.47, 95% CI: -0.16 to 1.10, p = 0.15) during the early postoperative period (≤ 3 weeks). At mid-term follow-up (8-14 weeks), BFRT significantly improved IKDC scores (SMD = 3.70, 95% CI: 0.20 to 7.21, p = 0.04). No significant differences were observed between the groups in the improvement of isometric strength of knee extensors (SMD = 0.50, 95% CI: -0.62 to 1.63, p = 0.38).

CONCLUSIONS

BFRT demonstrated limited effectiveness in early muscle strength recovery during ACLR rehabilitation but may have a positive impact on mid-term knee function, particularly in improving IKDC scores. However, due to heterogeneity and potential bias in the included studies, future research should incorporate more high-quality, multicenter RCTs to further validate the mid- to long-term value of BFRT in postoperative rehabilitation.

Patellar Dislocation Patients Had Lower Bone Mineral Density and Hounsfield Unit Values in the Knee Joint Compared to Patients with Anterior Cruciate Ligament Ruptures: A Focus on Cortical Bone in the Tibia

Anterior cruciate ligament (ACL) rupture and patellar dislocation (PD) are common knee injuries. Dual-energy X-ray absorptiometry (DXA) and computed tomography (CT) are widely used clinical diagnostic tools. The aim was to investigate the characteristics of knee bone mineral density (BMD) in patients with ACL rupture and PD and to explore the relationship between BMD and Hounsfield unit (HU) values. This prospective cross-sectional study included 32 ACL rupture and 32 PD patients assessed via DXA and CT. BMD and CT measurements were taken from regions of interest in the femoral and tibial condyles. Statistical analyses included t-tests and mixed-effects models. The results showed that BMD in the PD group was significantly lower than in the ACL group (p < 0.05). The HU values of cortical bone in the femur and tibia differed significantly between the ACL group and the PD group (p < 0.05). The BMD of the femur and tibia showed significant correlations with the HU values of cancellous bone and cortical bone (p < 0.05). The conclusion was that PD patients had lower BMD and HU values in the femur and tibia compared to patients with ACL ruptures, particularly in the cortical bone of the tibia, and there was a strong correlation between HU value and BMD.

Unilateral tests of lower-limb function as prognostic indicators of future knee-related outcomes following anterior cruciate ligament injury: a systematic review and meta-analysis of 13 150 adolescents and adults

OBJECTIVE

To investigate the prognostic capacity of individual hop tests, hop test batteries and other unilateral functional performance tests following anterior cruciate ligament (ACL) injury.

DESIGN

Systematic review with meta-analysis.

DATA SOURCES

Six databases searched up to June 2021.

ELIGIBILITY CRITERIA

Studies reporting associations between unilateral lower-limb function (eg, hop tests) following ACL injury and future (≥3 months) knee-related outcomes.

RESULTS

Of 42 included studies (13 150 participants), all assessed the single-forward hop test and 32 assessed a repeated-forward hop test (crossover hop, triple hop, 6m-timed hop), mostly within a year after ACL injury/reconstruction. Results of meta-analyses indicated that higher single-forward and repeated-forward hop limb symmetry were associated with higher odds of return-to-sport 1-3 years post-ACL reconstruction (OR 2.15; 95% CI 1.30 to 3.54; OR 2.11; 95% CI 1.23 to 3.60, respectively). Higher single-forward and repeated-forward hop limb symmetry was associated with better self-reported symptoms and function 1-37 years after ACL injury (OR 2.51; 95% CI 1.62 to 3.88; OR 4.28; 95% CI 1.65 to 11.08, respectively). Higher limb symmetry on a repeated-forward hop does not appear to be associated with higher odds of successful rehabilitation without ACL reconstruction (OR 1.51; 95% CI 0.94 to 2.44). Achieving ≥90% limb symmetry on the single-forward hop was associated with reduced odds of knee osteoarthritis 5-37 years after ACL injury (OR 0.46; 95% CI 0.23 to 0.94).

CONCLUSION

Very low certainty evidence suggests single-forward and repeated-forward hop tests are prognostic indicators for important knee-related outcomes in individuals after ACL injury and may help stratify individuals at risk of poor outcomes to target rehabilitation interventions.

PROSPERO REGISTRATION NUMBER

CRD42018092197.

Radiologic findings associated with mucoid degeneration of the anterior cruciate ligament

INTRODUCTION

Mucoid degeneration (MD) of the anterior cruciate ligament (ACL) is a well-recognized pathology characterized by the degradation of collagen fibers and infiltration of a mucoid-like substance. This study is to determine the anatomical associated factors for MD-ACL using radiographic and magnetic resonance imaging (MRI).

MATERIALS AND METHODS

This was a retrospective study on patients who had undergone knee arthroscopy between 2011 and 2020. The patients with MD-ACL were defined and enrolled by the MRI and arthroscopy. Eventually, 52 patients in the MD-ACL group (group 1) and 52 patients in the control group (group 2) were enrolled, following sex and age matching. Radiologic evaluation included the assessment of Kellgren-Lawrence (K-L) grade, mechanical hip-knee-ankle (HKA) angle, posterior tibial slope (PTS) angle, and Insall-Salvati ratio. The notch width index and transverse notch angle were measured on MRI, and the grade of trochlear dysplasia was defined. Logistic regression analysis, receiver operating characteristic (ROC) curves, and area under curve (AUC) were performed.

RESULTS

The ROM was significantly decreased in group 1, whereas the PTS angle was significantly larger in group 1. Combined ganglion cysts of ACL were found in 42/52 patients (80.7%) in group 1. The risk of MD-ACL was associated with a steeper PTS angle, increased Insall-Salvati ratio, male sex, higher K-L grade, and decreased transverse notch angle and notch width index. The cutoff values in ROC analysis were found to be ≤ 28.27% for the notch width index (AUC, 0.849; p < 0.001), > 12.2° for the PTS angle (AUC, 0.765; p < 0.001), and ≤ 47.4° for the transverse notch angle (AUC, 0.711; p < 0.001), but not significant for Insall-salvati ratio.

CONCLUSION

A steeper PTS angle, decreased notch width index, and transverse notch angle are significantly associated with the presence of MD-ACL. These factors should be considered during diagnosis or when determining the treatment strategy for symptomatic MD-ACL patients.

LEVEL OF EVIDENCE

Level IIIb.

The time from injury to surgery is an important factor affecting the mechanoreceptors at stump of torn anterior cruciate ligament

INTRODUCTION

Restoration of proprioceptive function after anterior cruciate ligament (ACL) reconstruction is as important as mechanical stability. For this purpose, remnant of the torn ACL is the only source of nerve endings. Our aim in this study is to investigate the quantity of mechanoreceptors in the remnants ACL stumps in injured knees and to correlate that with the quantity in intact ACL in control cases.

MATERIALS AND METHODS

48 patients that underwent ACL reconstruction between January 2016 and December 2018 as study group and 20 knees of 10 fresh frozen cadavers that as control group included in the study. Remaining stumps from study group and native ACL from control group were collected and investigated with S100 immunostaining. The type and number of mechanoreceptors in standardized areas was determined. The correlation of number of mechanoreceptors and time to surgery after ACL rupture were evaluated.

RESULTS

The free nerve endings (FNE) and total number of mechanoreceptors were significantly lower in the study group as compared to the control group (p < 0.001 and p = 0.004, respectively). The number of Golgi-Mazzoni corpuscle decreased significantly with time (p = 0.041 CC: - 0.438).

CONCLUSION

The time from injury to surgery is an important factor affecting the mechanoreceptors at stump of torn ACL. The surgeon and patient should be aware of the fact that delay in surgery could lead to the loss of mechanoreceptors.

Quadriceps and hamstring tendon autografts in ACL reconstruction yield comparably good results in a prospective, randomized controlled trial

INTRODUCTION

Comparable data of functional outcomes of anterior cruciate ligament reconstruction using either hamstring- or quadriceps tendon grafts is controversial. This prospective, randomized controlled trial aims to provide data comparing both grafts regarding the functional outcome.

MATERIALS AND METHODS

A two centre trial involving symptomatic patients 18 years of age or older with an anterior cruciate ligament tear was conducted. We randomly assigned 27 patients to quadruple hamstring tendon reconstruction and 24 to quadriceps tendon reconstruction. The patients were evaluated preoperatively, at 3, 6, 12 and 24 months post-surgery. The primary outcome parameter was the side-to-side knee laxity measured with an arthrometer. Secondary outcomes included results in the International Knee Documentation Committee (IKDC) and Lysholm Scores and isokinetic testing of strength in knee extension and flexion.

RESULTS

Forty-four patients (86%) completed the 2-year follow-up. There was significantly improved knee stability at all time intervals with no difference between the two study groups. The manual side-to-side displacement improved by 4.7 ± 3.0 mm in patients with hamstring tendon reconstruction and 5.5 ± 2.9 mm in patients with quadriceps tendon reconstruction. In addition, muscle strength and outcome scores (IKDC and Lysholm Score) did not show any differences between the hamstring tendon group and the quadriceps tendon group. Patients in the hamstring tendon group returned to their pre-injury activity level after 95.2 ± 45.5 days while patients in the quadriceps tendon group needed 82.1 ± 45.6 days.

CONCLUSION

Quadriceps and hamstring tendon autografts yield comparably good results in primary anterior cruciate ligament reconstruction.

Functional and molecular adaptations of quadriceps and hamstring muscles to blood flow restricted training in patients with ACL rupture

Effects of low-load blood flow restricted (LL-BFR) training remain unexplored in patients with ACL rupture. Our hypothesis was that LL-BFR training triggers augmented gains in knee muscle strength and size, which are paralleled with transcriptional responses of hypoxia-regulated genes and myokines. Eighteen volunteers (age 37.5 ± 9 years) planned for ACL reconstruction, participated in the study. Twelve were divided between BFR group, performing 9 sessions of LL-BFR exercise, and SHAM-BFR group performing equal training with sham vascular occlusion. Six subjects served as a control for muscle biopsy analysis. Cross-sectional area (CSA) and isokinetic strength of knee muscles were assessed before and after the training. Change in CSA_quad was significantly (p < 0.01) larger in BFR (4.9%) compared with SHAM-BFR (1.3%). Similarly, change in peak torque of knee extensors was significantly (p < 0.05) larger in BFR (14%) compared with SHAM-BFR (-1%). The decrease in fatigue index of knee extensors (6%) was larger (p < 0.01) in BFR than in SHAM-BFR (2%). mRNA expression of HIF-1α in the vastus lateralis was reduced (p < 0.05) in SHAM-BFR, while VEGF-A mRNA tended to be higher in BFR. The mRNA expression of myostatin and its receptor were reduced (p < 0.05) in the semitendinosus after both types of training. Expression of IL-6, its receptors IL-6Rα and gp130, as well as musclin were similar in control and training groups. In conclusion, our results show augmented strength and endurance of knee extensors but less of the flexors. LL-BFR training is especially effective for conditioning of knee extensors in this population.

Quadriceps tendon vs. patellar tendon autograft for ACL reconstruction using a hardware-free press-fit fixation technique: comparable stability, function and return-to-sport level but less donor site morbidity in athletes after 10 years

INTRODUCTION

The use of quadriceps tendon-patellar bone (QTB) autograft for anterior cruciate ligament (ACL) reconstruction is gaining momentum. Yet, long-term results that compare this procedure with established methods are lacking. The aim of this study was to report and compare long-term results of ACL reconstruction using QTB autografts versus bone-patellar tendon-bone (BPTB) autografts, both anchored using a hardware-free press-fit fixation technique.

MATERIALS AND METHODS

60 athletes (Tegner score ≥6) with primary ACL rupture were prospectively randomized into two groups. 56 patients were evaluated after a mean duration of 12.2 ± 1.9 months (range 10-14) and 43 patients after 10.3 ± 0.2 years (range 10-11).

RESULTS

On final follow-up, 90% of patients scored very good and good results in the functional Lysholm score (mean 99 ± 7.1, range 74-100 points). Normal or almost normal IKDC score was reported by 84% of the patients (mean 97 ± 9.5, range 60-100 points). The activity level decreased in the Tegner score from median of 7 before injury to 6 after 10 years. The KT-1000 arthrometer showed a difference in the anterior translation of less than 3 mm (mean 1.0 ± 1.2, range - 1 to 5 mm) in 91% of the patients. Significant degeneration was radiologically detected in one patient per group. No tunnel widening was seen in any patient. Up to 97% of all patients were satisfied with the operative procedure. No significant differences were found in the mentioned parameters between the two groups and also in comparison with the 1-year results. The only significant difference was in the donor site morbidity. Significantly more patients in the BPTB group had complaints during kneeling both at 1 (p < 0.001) and 10 years (p = 0.019). Squatting was also subjectively more problematic in the BPTB group than in the QTB group both after 1 (p = 0.003) and 10 years (p = 0.046).

CONCLUSIONS

This study shows equally good functional, clinical and radiological long-term results for both hardware-free methods of ACL reconstruction. These results clinically confirm the safety of press-fit anchoring after 10 years. The failure rate in this study was very low, with only one re-rupture in 10 years. The increased donor site morbidity when using the BPTB autograft compared to the QTB autograft supports already reported data. It was also seen in this study for the implant-free press-fit techniques.

STUDY DESIGN

Prospective and randomized, level of evidence 2.