Knee flexor strength following anterior cruciate ligament reconstruction with the semitendinosus and gracilis tendons

The Addition of the Gracilis Tendon to a Semitendinosus Tendon Autograft Is Not Associated With Knee Muscle Strength, Subjective Knee Function, or Revision Surgery After Anterior Cruciate Ligament Reconstruction

PURPOSE

To evaluate and compare isokinetic knee muscle (extension and flexion) strength, single-leg hop (SLH) test performance, anterior knee laxity, subjective knee function, and the 2-year revision surgery risk between patients who underwent anterior cruciate ligament reconstruction (ACLR) with semitendinosus tendon (ST) autografts and patients who underwent ACLR with ST and gracilis tendon (ST-G) autografts.

METHODS

We identified patients aged 16 years or older who underwent primary ACLR with hamstring tendon autografts at our institution from January 2005 to December 2020 and had no associated ligament injuries. Isokinetic knee muscle strength and SLH test performance were assessed 6 months postoperatively. Anterior knee laxity (KT-1000 arthrometer, 134 N) was assessed preoperatively and 6 months postoperatively. The Knee Injury and Osteoarthritis Outcome Score (KOOS) was collected preoperatively and 1 and 2 years postoperatively. Patients who underwent revision ACLR at any institution in Sweden within 2 years of primary surgery were identified through the Swedish National Knee Ligament Registry.

RESULTS

A total of 6,974 patients (5,479 with ST and 1,495 with ST-G) were included. There were no significant differences in extension and flexion strength or SLH test performance between the groups. Preoperatively, there was no significant difference in knee laxity between the ST and ST-G groups. Postoperatively, the ST-G group had significantly increased mean side-to-side (STS) laxity (2.1 ± 2.3 mm vs 1.7 ± 2.2 mm, P < .001) and showed a trend toward increased STS laxity according to the International Knee Documentation Committee form, with significantly fewer patients with STS laxity of 2 mm or less (58.4% vs 65.8%) and significantly more patients with STS laxity between 3 and 5 mm (35.0% vs 29.9%) or greater than 5 mm (6.6% vs 4.3%) (P < .001). The only significant difference in subjective knee function was for the KOOS Quality of Life subscale score in favor of the ST group preoperatively (37.3 ± 21.4 vs 35.1 ± 19.9, P = .001). No other significant differences between the groups were found preoperatively and 1 and 2 years postoperatively for any of the KOOS subscales. The overall revision ACLR rate within 2 years of primary surgery was 2.0% (138 of 6,974 patients). The revision ACLR risk in the ST-G group (1.7%, 25 of 1,495 patients) was not significantly different from that in the ST group (2.1%, 113 of 5,479 patients) (hazard ratio, 0.80; 95% confidence interval, 0.50-1.24; P = .32).

CONCLUSIONS

The addition of the gracilis tendon to an ST autograft was not associated with knee muscle strength, SLH test performance, subjective knee function, or the risk of revision surgery after ACLR.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

Enlightenment on Knee Flexors Strength Loss in Cases of Posterior Knee Pain After Anterior Cruciate Ligament Reconstruction

CONTEXT

The persistence and the recurrence of posterior medial knee pain (PKP) after anterior cruciate ligament reconstruction (ACLR) using hamstring tendon graft are often overlooked during rehabilitation.

DESIGN

Cross-sectional observational study.

METHODS

The study aimed (1) to evaluate the prevalence of these types of PKP before 4 months post-ACLR, (2) to measure their consequences on the knee flexors strength, and (3) to evaluate the role of the type of ACLR. From a cohort of patients operated on with hamstring tendon procedures, the persistent and the recurrent PKP were sought at 4 months post-ACLR. The evolution of isokinetic muscle strength recovery in PKP subjects was compared with those of nonpainful subjects. The functional deficit was measured at 6/7 months post-ACLR by a hop test.

RESULTS

Three hundred seventeen subjects (25.8 [6.0] y) were included. At 4 months post-ACLR, 2 populations were identified based on the recurrent onset of PKP (PKP+, n = 40) or the absence of knee pain (PKP-, n = 277). The prevalence of PKP was 8.3%. At the fourth month post-ACLR, the PKP+ group had a higher flexor strength deficit compared with the PKP- group (limb symmetry index at 60°/s: 67.2% [12.4%] vs 84.3% [12.6%]; P < .05). At 6/7 months, the loss of strength persisted (limb symmetry index at 60°/s: 82.3% [13.4%] vs 87.7% [12.8%]; P < .05). The hop test deficit was comparable, and no difference was shown according to the type of graft.

CONCLUSIONS

Persistent and recurrent PKP during the rehabilitation period were not uncommon and were associated with a worsening of flexors strength loss on the ACLR side.

The effect of gracilis tendon harvesting in addition to semitendinosus tendon harvesting on knee extensor and flexor strength after anterior cruciate ligament reconstruction

INTRODUCTION

Anterior cruciate ligament (ACL) reconstruction using hamstring tendons may involve harvesting of the gracilis tendon in addition to the semitendinosus tendon (ST) depending on the size of the ST graft. However, the effect of gracilis harvesting in addition to ST harvesting on muscle strength, such as the hamstring-to-quadriceps (HQ) ratio, remains unclear. Hence, this study aimed to investigate the effect of gracilis harvesting on subsequent knee muscle strength.

MATERIALS AND METHODS

Eighty-two patients who underwent ACL reconstruction were included in this retrospective study. They were divided into the following two groups depending on the tendon graft used for ACL reconstruction: the ST group (41 patients) and the semitendinosus tendon/gracilis tendon (STG) group (41 patients). The isokinetic peak torque of the knee extensor and flexor was measured using a BIODEX dynamometer at a velocity of 60°/s and 180°/s, respectively, 3 and 6 months after ACL reconstruction. The groups were compared in terms of the limb symmetry index (LSI) and HQ ratio.

RESULTS

The significant difference in the knee flexor of the LSI at 6 months after ACL reconstruction was as follows: ST group, 120.3 ± 28.3 vs STG group, 105.6 ± 19.0 (p < 0.01) at 60°/s and ST group, 122.9 ± 35.2 vs STG group, 106.2 ± 24.6 (p = 0.02) at 180°/s. There were significant differences in the HQ ratio at 180°/s as follows: ST group, 0.67 ± 0.15 vs STG group, 0.60 ± 0.13 (p < 0.01) at 3 months and ST group, 0.67 ± 0.13 vs STG group, and 0.59 ± 0.12 (p < 0.01) at 6 months after ACL reconstruction.

CONCLUSIONS

Gracilis tendon harvesting may contribute to a decrease in knee flexor strength and HQ ratio with fast contraction. Thus, the need for gracilis tendon harvesting in ACL reconstruction should be carefully considered.

LEVEL OF EVIDENCE

III.

Effect of Hamstring-to-quadriceps Ratio on Knee Forces in Females During Landing

ACL injuries in the athletic population are a common occurrence with over 70% associated with non-contact mechanisms. The hamstring to quadriceps ratio is a widely used clinical measure to assess an athlete's readiness to return to sport; however, its relationship to knee forces and ACL tension during landing is unknown. Baseline isokinetic testing was completed on 100 college-aged females. Subjects with strength ratios 0.4 (n=20) and those with ratios of 0.6 (n=20) returned for an assessment of their drop landing. A sagittal plane knee model determined the low ratio group demonstrated 16.6% larger ligament shear (p=0.000), a 26% increase in tibiofemoral shear force (p=0.026) and a 6% increase vertical force between the femur and tibial plateau (p=0.026) compared to the high hamstring ratio group within 100 ms upon impact. The lower ratio group also demonstrated 9.5% greater maximal quadriceps (p=0.028) force during landing. These findings suggest that the hamstring to quadriceps ratio may be related to knee forces and ACL loading during landing. This metric may augment clinical decision making regarding an athlete's readiness to return to sport or relative risk for re-injury.

Clinical, functional, and isokinetic study of a prospective series of anterior cruciate ligament ligamentoplasty with pedicular hamstrings

PURPOSE

Few studies describe the specific results of anterior cruciate ligament reconstruction with pedicled hamstring graft (HG). Our goal was to report the isokinetic, clinical, and functional outcomes over the post-operative year following pedicled hamstring ligamentoplasty.

METHODS

Twenty-four patients with ACL rupture (mean age 27.4 years) were included prospectively. The technique used a four-stranded HG transplant pedicled to the tibia. The functional result (Lysholm knee score and subjective IKDC score), clinical result (KT-1000, Lachman test, joint amplitudes, objective IKDC score), and isokinetic complication occurrence were analyzed at six months and 12 months follow-up. The functional results, clinical parameters, and complications were analyzed at 30 months follow-up. The comparison of the variables with the various regressions was carried out by a Wilcoxon sign test.

RESULTS

Twenty-one patients were reviewed at six, nine, 12, and 30 months. The mean Lysholm knee score was 90/100 at six months, 96/100 at one year, and 95/100 at 30 months. The mean subjective IKDC score was 77/100 and 89/100 at six and 12 months, and 91/100 at 30 months. The mean difference in laxity compared with the healthy knee was 1.4 mm at six months, 1.9 mm at 12 months, and 2 mm at 30 months. The objective IKDC score was A or B for all patients at 12 and 30 months. The average quadriceps strength deficit decreased from 27 to 16% between six and 12 months post-operative (p = 0.0091) and the average flexor deficit from 23 to 12% (p = 0.0084). No complications were identified.

CONCLUSION

The abovementioned technique allows reaching functional, clinical, and isokinetic results comparable with the standard techniques while preserving the mechanical and biological interest of tibial insertion.

Clinical experience with woven and parallel hamstring-tendon anterior cruciate ligament reconstruction

PURPOSE

The purpose of this study was to determine the effect of the weave technique for hamstring graft preparation on the diameter of the prepared graft, functional outcome, and need for harvesting of semitendinosus and gracilis (ST + G) or semitendinosus alone (ST).

MATERIALS AND METHODS

This retrospective study evaluated 340 patients who underwent arthroscopic anterior cruciate ligament (ACL) reconstruction from January 2013 to December 2015. Our protocol for graft preparation is that the graft length must be a minimum of 8 cm and the diameter must be between 7 and 10 mm. The parallel-graft preparation technique was used in 189 patient and the weave technique was used in 151 patients. Outcome was measured by using stress radiographs and International Knee Documentation Committee (IKDC) 2000 score.

RESULTS

In the parallel-graft preparation group, ST + G was used in 99 patients and ST was used in 90 patients. In the weave-graft preparation group, ST + G was used in 38 patients and ST alone was sufficient in 113 patients. The need for G harvest was less in the weave-technique group (p < 0.0001). There was no statistically significant difference at 2 years of follow-up in stress laxiometry, IKDC 2000 scores and rerupture rates between the two groups.

CONCLUSION

The weave technique helps to reduce the need for G harvest without compromising functional outcome. Level of evidence IV.

Comparison of results after anterior cruciate ligament reconstruction using a four-strand single semitendinosus or a semitendinosus and gracilis tendon

PURPOSES

To compare the clinical and functional results of anterior cruciate ligament (ACL) reconstruction using an autologous four-strand single semitendinosus (ST) tendon or a ST and gracilis tendon. It was hypothesized that successful ACL reconstruction using a single ST tendon without the gracilis tendon could provide comparable knee stability and reduce donor site morbidity.

METHODS

This study evaluated 144 cases of single-bundle ACL reconstruction using an autologous hamstring tendon. The ST group included 85 cases of reconstruction using a single ST tendon, and the ST/G group included 59 cases of reconstruction using a ST tendon and a gracilis tendon. An extracortical suspension device and a suture tied around a screw post with an additional bioabsorbable screw were used to fix the femoral and tibial tunnels, respectively. Clinical evaluations involved the Lachman, pivot-shift, and one-leg hop tests; an isokinetic test; a KT-2000 arthrometer; an assessment of return to pre-injury activities; and Lysholm, Tegner activity, and International Knee Documentation Committee (IKDC) subjective scores.

RESULTS

No significant differences were found between the ST and ST/G groups with respect to the Lysholm, Tegner activity, and subjective IKDC scores; the Lachman, pivot-shift, and one-leg hop tests; KT-2000 arthrometer side-to-side differences; or return to pre-injury activities. However, mean peak torque deficit, as determined using the isokinetic test during flexion at 60°/s, was significantly lower in the ST group than in the ST/G group (p = 0.047).

CONCLUSION

This study showed good results for ACL reconstruction using a single ST tendon without deterioration of stability. This provides the evidence that ACL reconstruction using a single ST tendon without the gracilis tendon decreases donor site morbidity without compromising joint stability.

LEVEL OF EVIDENCE

IV.

Does Gracilis Tendon Harvest During ACL Reconstruction with a Hamstring Autograft Affect Torque of Muscles Responsible for Shin Rotation?

Background

A growing body of evidence indicates that in patients after anterior cruciate ligament reconstruction (ACLR) with a combined semitendinosus and gracilis (STGR) graft there are large deficits in the internal rotation strength, which has led some authors to recommend harvest of only ST tendon whenever possible. The purpose of this study was to assess the isometric (IT) and peak torque (PT) of the muscles responsible for shin rotation in patients after ACLR with an ST or with an STGR graft.

Material/Methods

Twenty patients with an ST graft and 20 patients with a combined STGR graft underwent a 6-month postoperative rehabilitation program after ACLR. At the end of the rehabilitation program, the IT and PT of the muscles responsible for internal (IR) and external rotation (ER) of the shin were measured. The results were compared to the results of a control group. Additionally, to determine the reliability of the dynamometer for clinical research, a test-retest assessment was performed.

Results

There were no statistically significant differences between the 3 groups of participants. Nevertheless, in the STGR group there was a statistically significant difference between the IT of muscles internally rotating the shin in the involved knee and uninvolved knee at 25° of the internal shin rotation.

Conclusions

Comparison of IT and PT measurements performed after 24 weeks of postoperative rehabilitation generally showed no differences between patients after ACLR with the use of ST graft and patients who received a combination graft consisting of STGR. Nevertheless, there was an influence of GR harvest on internal shin rotation torque at a deep internal rotation angle.

A meta-analysis of bone-patellar tendon-bone autograft versus four-strand hamstring tendon autograft for anterior cruciate ligament reconstruction

BACKGROUND

There is a lack of comprehensive studies comparing the clinical outcome of anterior cruciate ligament (ACL) reconstruction with either a bone-patellar tendon-bone (BPTB) or four-strand hamstring tendon (4SHT) autografts. The optimal choice of graft for anterior cruciate ligament reconstruction remains controversial.

PURPOSE

The objective of this study was to evaluate the effectiveness of BPTB autografts versus 4SHT autografts for the reconstruction of ACL.

METHODS

A systematical search of literature was performed in Pubmed, Embase, and the Cochrane library to identify published clinical prospective studies relevant to ACL reconstruction comparing BPTB and 4SHT autografts. The results of the eligible studies were analysed in terms of instrumented laxity measurements, Lachman test, pivot shift test, objective International Knee Documentation Committee (IKDC) scores, return to preinjury activity level, and morbidity of graft failure, anterior knee pain, kneeling pain, extension deficit, and flexion deficit. Study quality was assessed by using the Jadad scale for randomized clinical trial (RCT) and the Newcastle-Ottawa Scale (NOS) for prospective cohort study (PCS). Two reviewers independently assessed each study for quality and extracted data. Subgroup analysis of the primary outcomes was conducted according to the type of study design (RCT or PCS).

RESULTS

Twenty-two studies, with 931 patients in the BPTB group and 999 patients in the 4SHT group, met the inclusion criteria. Fourteen studies were randomized controlled trials, and eight were prospective cohort studies. The results of the meta-analysis showed that there were no significant differences between BPTB and 4SHT in terms of instrumented laxity measurements (P=0.06), Lachman test (P=0.58), objective IKDC scores (P=0.31), graft failure (P=0.45), extension deficit (P=0.06) and flexion deficit (P=0.63). However, outcomes in favour of BPTB were found in terms of pivot shift test (P=0.01) and return to preinjury activity level (P=0.03); outcome measures that favours 4SHT included anterior knee pain (P<0.01) and kneeling pain (P<0.01). These findings were still robust during the sensitivity analysis. Results from subgroup analysis of the primary outcomes were consistent with the overall analysis.

CONCLUSION

Based on the results above, ACL reconstruction with BPTB autografts might be superior in resuming rotation stability of the knee joint and allow patients to return to higher levels of activity in comparison with 4SHT autografts. Whereas, postoperative complications of the knee joint were lower for 4SHT autografts than for BPTB autografts. There was insufficient evidence to identify which of the two types of grafts was significantly better for ACL reconstruction considering the limitations of this study. More high-quality randomized controlled trials with strictly specified inclusion criteria are highly required before drawing a reliable conclusion.

Quality of life and clinical outcome comparison of semitendinosus and gracilis tendon versus patellar tendon autografts for anterior cruciate ligament reconstruction: an 11-year follow-up of a randomized controlled trial

BACKGROUND

There are still controversies about graft selection for primary anterior cruciate ligament reconstruction. Prospective, randomized long-term studies are needed to determine the differences between the graft materials.

HYPOTHESIS

Eleven years after anterior cruciate ligament reconstruction there is no difference in functional outcome and quality of life between patients with patellar tendon or hamstring tendon autografts; however, the patients with patellar tendon autograft would have a higher prevalence of osteoarthritis.

STUDY DESIGN

Randomized controlled trial; Level of evidence, 2.

METHODS

From June 1999 to March 2000, 64 patients were included in this prospective study. A single surgeon performed primary arthroscopically assisted anterior cruciate ligament reconstruction in an alternating sequence. In 32 patients, anterior cruciate ligament reconstruction was performed with hamstring tendon autograft (semitendinosus and gracilis [STG] group) while in the other 32 patients the reconstruction was performed with patellar tendon autograft (PT group).

RESULTS

At the 11-year follow-up, no statistically significant differences were seen with respect to the Lysholm score and Short Form-36, KT-1000 arthrometer laxity testing, anterior knee pain, single-legged hop test, or International Knee Documentation Committee (IKDC) classification results. Positive pivot-shift test (1+) was significantly more frequent in the PT group (P = .036). Twenty-two patients (81%) in the STG group and 18 patients (72%) in the PT group were still at their preinjury level of activity. Graft rupture occurred in 2 patients from the STG group (6%) and in 4 patients from the PT (12%). Grade B and C abnormal radiographic findings were seen in 84% (21 of 25) of patients in the PT group and in 63% (17 of 27) of patients in the STG group (P = .008).

CONCLUSION

Both hamstring and patellar tendon autografts provided good subjective outcomes and objective stability at 11 years. Positive pivot-shift test (1+) was significantly more frequent in the PT group. No significant differences in the rate of graft failure were identified. Patients with patellar tendon graft had a greater prevalence of osteoarthritis at 11 years after surgery.

Effects of running retraining after knee anterior cruciate ligament reconstruction

OBJECTIVE

The aim of this study was to analyze the effect of running retraining on the recovery of the knee's functional and muscular properties after anterior cruciate ligament (ACL) reconstruction.

METHODS

Eighty-five athletes who had undergone ACL reconstruction surgery were selected randomly to receive, or not to receive, controlled running training based on interval training and speed exercises. The effect of retraining was measured by the evolution of the knee's isokinetic strength deficit and progress (at angular speeds of 60 and 180 degrees /s), the knee laxity parameters and the score on the Lysholm Knee Scale from the 4th to the 6th month after the surgery. Forty subjects were retrained and compared with 40 control-group subjects. The effect of the retraining program was studied in terms of the type of ACL reconstruction and the effect of time.

RESULTS

After retraining, no difference was found for isokinetic knee strength deficit and progress, knee laxity and Lysholm Knee Score. The isokinetic strength deficit was influenced mainly by the type of ACL reconstruction.

CONCLUSION

It would seem that running retraining has an insufficient effect on the muscular and functional recovery after ACL reconstruction, despite the fact that this type of training is well-tolerated.

COMPARISON BETWEEN THE RESULTS ACHIEVED IN ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION WITH TWO KINDS OF AUTOLOGOUS GRAFTS: PATELLAR TENDON VERSUS SEMITENDINOUS AND GRACILIS

Objective: this study aims to compare the arthrometric and isokinetic examination results from two types of autologous grafts: the central third of the patellar ligament and a graft formed by the tendons of the semitendinosus and gracilis muscles, within the same rehabilitation protocol, six months after the surgery. Methods: the results from examinations carried out on 63 patients were analyzed. These patients were divided in two groups: one group of 30 patients who received a patellar tendon graft and another group of 33 patients who received a graft from the tendons of the semitendinosus and gracilis muscles. Both the grafts were attached in the same way, with Endobutton™ for suspensory fixation to the femur and a bioabsorbable interference screw for fixation in the tibial tunnel. Results: arthrometry 30 did not present any statistical difference between the two study groups. On the other hand, the isokinetic evaluation showed that the patellar tendon group had a larger mean peak torque of flexion and greater extension deficit, while the semitendinosus/gracilis group had a better mean flexion/extension ratio and greater percentage of flexion deficit. There was no statistically significant difference between the groups when measuring peak torque extension. Conclusion: therefore, when the patellar tendon was used, there was greater extensor deficit and, when the semitendinosus/gracilis tendons were used, there was greater flexor deficit.

The effect of graft choice on functional outcome in anterior cruciate ligament reconstruction

A prospective, randomised, 5-year follow-up study was designed to compare the functional results between patellar tendon and hamstring tendon autografts after anterior cruciate ligament reconstruction. Primary reconstruction was performed in 32 patients using the central third of the patellar ligament and in 32 patients using double-looped semitendinosus and gracilis tendons. All reconstructions were performed by a single surgeon, with identical surgical technique and rehabilitation protocol. Of the total 64 patients in the study, 54 (85%) were available for the 5-year follow-up. No statistically significant differences were seen with respect to Lysholm score, International Knee Documentation Committee (IKDC) classification, clinical and KT-2000 arthrometer laxity testing, single-legged hop test and anterior knee pain. Graft rupture occurred in two patients (8%) in the patellar tendon group and in two patients (7%) in the hamstring tendon group; 23 patients (88%) in the patellar tendon group and 23 patients (82%) in the hamstring tendon group returned to their pre-injury activity level. Good subjective outcome and stability can be obtained by using either graft; no statistically significant differences were found in functional outcome between the grafts.

A prospective, randomized comparison of semitendinosus and gracilis tendon versus patellar tendon autografts for anterior cruciate ligament reconstruction: five-year follow-up

BACKGROUND

There are still controversies about graft selection for primary anterior cruciate ligament reconstruction. Prospective randomized long-term studies are needed to determine the differences between the materials.

HYPOTHESIS

Five years after anterior cruciate ligament reconstruction, there is a difference between hamstring and patellar tendon grafts in development of degenerative knee joint disease.

STUDY DESIGN

Randomized controlled trial; Level of evidence, 1.

METHODS

From June 1999 to March 2000, 64 patients were included in this prospective study. A single surgeon performed primary arthroscopically assisted anterior cruciate ligament reconstruction in an alternating sequence. In 32 patients, anterior cruciate ligament reconstruction was performed with hamstring tendon autograft, whereas in the other 32 patients, anterior cruciate ligament reconstruction was performed with patellar tendon autograft.

RESULTS

At the 5-year follow-up, no statistically significant differences were seen with respect to the Lysholm score, clinical and KT-2000 arthrometer laxity testing, anterior knee pain, single-legged hop test, or International Knee Documentation Committee classification results; 23 patients (82%) in the hamstring tendon group and 23 patients (88%) in the patellar tendon group returned to their preinjury activity levels. Graft rupture occurred in 2 patients from the hamstring tendon group (7%) and in 2 patients from the patellar tendon group (8%). Grade B abnormal radiographic findings were seen in 50% (13/26) of patients in the patellar tendon group and in 17% (5/28) of patients in the hamstring tendon group (P = .012).

CONCLUSION

Both hamstring and patellar tendon grafts provided good subjective outcomes and objective stability at 5 years. No significant differences in the rate of graft failure were identified. Patients with patellar tendon grafts had a greater prevalence of osteoarthritis at 5 years after surgery.

Réentraînement à l'effort entre le quatrième et le sixième mois après ligamentoplastie de genou au DIDT : comparaison de la pratique de la bicyclette et de la pratique du footing avec un groupe témoin non réentraîné

OBJECTIVE

To study the effect of cycling or running retraining between 4 and 6 months after patients underwent anterior cruciate ligament reconstruction with hamstring grafting (Semitendinosus-Gracilis) compared with that in patients who had the same surgery but were untrained.

METHOD

Patients who had undergone surgery for an anterior cruciate ligament reconstruction by the same surgeon who used hamstring grafting were included if they were free of knee pain 4 months after the surgery. After giving consent, patients were randomized to receive controlled retraining (cycling or running 3 times a week) or not. The effect of retraining was measured by the evolution of the knee isokinetic peak torque at 60 degrees/s and 180 degrees/s 6 months after surgery.

RESULTS

Fifteen patients were retrained with cycling (GI), 17 with running (GII) and 15 patients did not retrain (GIII). Before retraining, the 3 groups had the same peak torque deficit, measured at an angular speed of 60 degrees/s and 180 degrees/s, for knee extensors (GI: 33+/-11% and 27+/-8%; GII: 30+/-13% and 24+/-10%; GIII: 31+/-15% and 24+/-13%, respectively) and knee flexors (GI: 26+/-11% and 20+/-13%; GII: 20+/-14% and 17+/-13%; GIII: 19+/-15% and 14+/-15%, respectively). After retraining, progress measured at 60 degrees /s of knee extensors and flexors on the operated knees was 18+/-9% and 16+/-10% for GI, 16+/-9% and 11+/-11% for GII and 12+/-15% and 8+/-12 for GIII, respectively. Progress measured at 180 degrees /s followed the same evolution. After comparison of the 3 groups, any significant difference was put in relief according to the type of retraining.

CONCLUSION

Retraining after anterior cruciate ligament reconstruction is necessary for patients to practice their previous sport. In our study, aerobic cycling or running between 4 and 6 months after surgery did not improve peak torque in the operated knee extensors and flexors. However, these 2 types of retraining are well-tolerated.

Medial hamstring tendon regeneration following harvest for anterior cruciate ligament reconstruction: fact, myth, and clinical implication

It has been demonstrated that the medial hamstring tendons regenerate in the majority of patients following their harvest for anterior cruciate ligament reconstruction. The anatomy and morphology of these regenerated tendons have been radiographically and surgically documented. The neotendons originate within the appropriate muscle belly but display an altered insertion anatomy. Their histological composition is largely tendinous but has regions that resemble scar tissue. Concordantly, an animal model indicates that the neotendon has decreased mechanical strength, which has implications for tendon re-harvest. The regenerated tendons do restore a muscle tendon complex that is able to generate force; however, strength testing indicates that the function of the hamstring muscles is altered by harvest and regeneration. The most significant strength deficits are present in deep knee flexion and internal rotation of the tibia, whereas the peak torque of knee flexion is minimally affected. Additional harvest of the gracilis tendon results in greater deficits. The current literature indicates that hamstring tendon regeneration does indeed occur, but with structural and functional alterations.

In-vivo sagittal plane knee kinematics: ACL intact, deficient and reconstructed knees

Sagittal plane video fluoroscopy was used to analyse the bilateral knee kinematics of patients with unilateral ACL deficiency (ACLD) before, and 4 months after, hamstrings graft ACL reconstruction. Kinematics were studied during weight resisted knee extension, passive knee extension, and a step up. Thigh EMG records were also obtained from five subjects. In addition, six uninjured control subjects were analysed to establish normal kinematics. Kinematics were analysed by calculating the angle between the long axis of the tibia and the patella tendon through the range of knee flexion. Shear forces were calculated using a model of knee extension and force plate data. A maximum anterior TT of 7.3 (S.D. 2.1) mm was recorded in ACL intact (ACLI) knees during the weightbearing activity. Hamstrings activity was able to control ATT in the ACLD tibia to within the normal range of translation of the ACLI knee. Despite clinical improvements, ATT increased postoperatively in the reconstructed knees to 11.6 (S.D. 3.8) mm (P<0.048). The findings suggest that the ACL has only a minor role in the control of ATT during activity, and that the extent of ATT is more closely related to the level of quadriceps-generated shear force. A reduction in hamstrings force is proposed as the most likely cause for increased ATT post reconstruction. These findings have implications for the development of ACL rehabilitation regimes, and also may modify graft choice and the surgical aims of the procedure.

Muscle and tendon morphology after reconstruction of the anterior cruciate ligament with autologous semitendinosus-gracilis graft

BACKGROUND

The autologous semitendinosus-gracilis graft is the first choice of many orthopaedic surgeons when reconstructing the anterior cruciate ligament. The effect that graft harvest has on muscle and tendon morphology remains unclear. The purpose of this study was to describe these effects more completely.

METHODS

Magnetic resonance images were acquired from eight patients before the anterior cruciate ligament reconstruction with semitendinosus-gracilis autograft and then again postoperatively after they had returned to sports. Muscle and tendon morphology was described by determining the volume and peak cross-sectional area of each structure on digitally reconstructed images. The effects that the procedure had on muscle and tendon length were evaluated separately and then together as a muscle-tendon complex.

RESULTS

Anterior cruciate ligament reconstruction with semitendinosus-gracilis autograft resulted in a marked decrease in volume, cross-sectional area, and length of the semitendinosus and gracilis muscles. Tendon regeneration occurred in varying degrees in nearly all subjects. The morphology of the biceps femoris and semimembranosus muscles suggested that they had been compensating for the reduced semitendinosus and gracilis muscle function. Although semitendinosus and gracilis muscle retraction occurred following tendon stripping, nearly all of the subjects displayed evidence of at least partial tendon regeneration.

CONCLUSIONS

Anterior cruciate ligament reconstruction with semitendinosus-gracilis autograft had a marked impact on semitendinosus and gracilis muscle morphology. However, this altered muscle morphology did not appear to have a clinically important impact on short-term outcomes. The biceps femoris and semimembranosus muscles appear to compensate for reduced semitendinosus and gracilis function. Tendon regeneration is observed in most people, but it is often incomplete at six months.