Purpose: We studied early recovery of knee muscles after harvesting the hamstrings for arthroscopic reconstruction of the anterior cruciate ligament (ACL) using an isokinetic testing device (Biodex®).

Material: This prospective consecutive series included 22 athletes (twelve amateur athletes and ten competition level athletes) who presented a full thickness tear of the ACL without associated lesions. Intra-articular and extra-articular ligamentoplasty using the gracilis and semi-tendinous was performed arthroscopically by the same surgeon. The same rehabilitation program was prescribed for all patients.

Method: The flexor and extensor system of both knees was assessed for each patient using the Biodex® device operating in concentric isokinetic mode. Tests were performed at two speeds 90 and 180°/s and at three times: preoperatively, and four and seven months postoperatively. The peak couple and mean power during a series of six flexion-extension movements were retained for this analysis.

Mean values remained unchanged for the three test times for the healthy knees. We therefore chose the preoperative values obtained for the healthy knee as the paired reference value for each patient. The values obtained for the operated knees were compared with these control values using two-way analysis of variance for paired variables.

Results: At four months postop, flexor and extensor muscles exhibited significant (p < 0.05) and equivalent diminution. However, 25% of the patients had already achieved 80% recovery, sufficient for renewed sports activities. At seven months postop, the extensors had totally recovered and the flexors remained significantly diminished (related to hamstring harvesting); 65% of the patients had reached 80% recovery, but 90% of the competition level athletes had recovered more than 80%. The statistical analysis demonstrated a positive correlation between muscle recovery at seven months and preoperative muscle level: the patients with higher preop levels having the higher postop levels.

Discussion: These results suggest the following: preoperative rehabilitation exercises (to start with a higher preop level), more work on the flexors (limiting factor), new recovery objectives (80% at four months, 100% at seven months). Currently, we authorise renewed sports activities on the basis of muscle recovery as assessed by isokinetic tests which are performed at four months for competition level athletes and seven months for amateur athletes.

Purpose: The purpose of this study was to: 1) assess outcome of ACL reconstruction with intra- and extra-articular hamstring plasty; 2) analyse the contribution of a synthetic lateral reinforcement by comparing two series.

Material and methods: This population of 100 patients was divided into two groups: group 1 with a synthetic lateral reinforcement (70 patients) and group 2 without lateral reinforcement (30 patients). Eighty-nine percent of the patients were reviewed. Mean age at operation was 28 years. Fifty-six percent of the patients were competition-level athletes (pivot sports) and lesions of the medial meniscus was observed peroperatively in 74% of the patients. Mean follow-up was 40 months. The two groups were comparable for all parameters studied except follow-up and age which were slightly lower in group 2 without reinforcement. ARPEGE and IKDC scores (with KT1000 at 89N) were established. We performed a precise analysis of residual laxity (TELOS at 15 kg). The position and the width of the bore holes were also analysed.

Results: According to the ARPEGE scores, outcome was excellent or very good in 71% of the patients and 87% were in IKDC classes A and B. Seventy percent of the patients who were competition-level athletes (pivot sports) resumed their activities at the same level. Residual differential laxity (TELOS) was 5.7 mm (mean). Tunnel width was 3.5 mm (mean). This work demonstrated the safety of hamstring harvesting.

Discussion Residual laxity was strongly correlated with clinical outcome: residual differential laxity less than 6 mm (threshold value) ensured a negative pivot test and 94% good results. We did not find any correlation between tunnel width and residual laxity. An overly anterior femoral position and medial meniscectomy significantly increased residual laxity. The femoral bore hole should be sufficiently posterior, 60 to 70% of the anteroposterior condylar width. Use of a synthetic reinforcement did not improve clinical or laximetric outcome in the reinforcement group; a natural plasty without synthetic reinforcement would be preferable.