Purpose of the study: Spontaneous repair of lost deep chondral tissue is minimal in the knee joint. A clinical trial of chondrocyte autografts as described by Brittberg and Peterson was undertaken by the Nantes University Hospital and the French Society of Arthroscopy in 1999.

Material and methods: Twenty-eight patients, mean age 28 years, underwent surgery in eight centers. Etiologies were: osteochondritis (n=14), isolated posttraumatic chondorpathy (n=7), chondropathy and full-thickness ACL tear (n=7). All lesions involved the condyles and were deep (ICRS grades 3 and 4). Mean surface area involved after debridement was 490 mm2 (range 150–1000 mm2). Patients were followed three years after the autologous grafting to assess functional outcome. An MRI was obtained at 2–3 years. Thirteen control arthroscopy procedures were performed including eight with biopsy specimens for histology and immunohisto-chemistry studies.

Results: Twenty-six patients were reviewed at more than two years. There were no general complications, three patients presented a partial avulsion of the graft treated by arthroscopy and one underwent arthrolysis at six months. Function improved in all patients except three and pain improved in all. The ICRS score improved from 43 points (range 19–70) to 77 points (range 39–84). Sixteen control MRIs were available and showed that the graft was hypertrophic in eleven cases, on level in four, and insufficient in one. Marginal integration was good in 11 cases and partial in five. Subchondral integration was complete in ten cases and mediocre in six. The arthroscopic score was nearly normal (score 8–11) in eight cases and abnormal in five (score 4–7). The histological class according to Knutsen (hyaline richness) was: one in group 1 (> 60%), three in group 2 (> 40%), four in group 3 (< 40%) and one in group 4 (bony or fibrous tissue). Function score (r=0.78 and MRI score (r=0.76) were correlated with arthroscopic sores. There was no correlation with the histological results.

Discussion: Clinical outcome was improved in more than 80% of cases, similar to results reported for histological series. The arthroscopic and histological results were equivalent to those reported by Knutsen but inferior to those reported by Bentley or Peterson.

Purpose: The anterior cruciate ligament (ACL) is composed of two strands, the anteromedial (AM) and the posterolateral (PL). Each strand has a distinct biomechanical role. The classical techniques for reconstruction of the ACL using a one-strand graft cannot replace the AM strand of the ligament. Control of knee laxity after graft reconstruction with a single strand cannot restore physiological laxity.

Material and methods: This study was performed on 16 matched cadaver knees randomised for reconstruction technique. Anterior tibial dislocation was measured with the Rolimeter arthrometer using manual traction on the intact knee, after section of the ACL, and after arthroscopic reconstruction of the ACL using a 2-strand or 4-strand hamstring method at 20°, 60°, and 90° flexion. Changes in the length of each reconstructed strand were measured.

Results: For the 16 intact knees, anterior laxity was measured at 20°, 60° and 90°. After section of the ACL, laxity increased significantly at all angles studied. Statistical parametric and non-parametric tests demonstrated a significant difference between laxity after ACL section and after ACL reconstruction (one-strand) at 20°, 60° and 90° flexion. There was a significant difference between intact ACL and reconstructed ACL at 20° flexion, the residual laxity was greater after one-strand reconstruction. Conversely, at 60° and 90°, there was no difference in anterior displacement of the tibia for intact and reconstructed ACL. There was a statistically significant improvement in laxity between sectioned and reconstructed (two-strand) ACL at 20°, 60° and 90° but no difference in anterior dislocation between the intact ACL and the reconstructed ACL at 2°, 60°, and 90° flexion.

Conclusion: Two-strand reconstruction of the ACL provides laxity comparable with that of the intact ACL at 20°, 60°, and 90° flexion while one-strand reconstruction only re-establishes physiological laxity at 60° and 90°.

Purpose: Lateral hypoaesthesia of the knee following peroperative section of an infrapatellar sensorial branch during anteromedial access for knee surgery is a well-known phenomenon. Development of a painful neurinoma at this level is much more exceptional but can be the cause of persistent pain, often becoming violent in the anteromedial region of the proximal tibia which may often evoke the diagnosis of mechanical failure of the prosthesis due to superficial conflict or loosening. There is relatively little in the French orthopaedic literature on this topic. We wanted to draw attention to this often missed diagnosis.

Material and methods: We report the cases of three patients with degenerative knee disease who underwent total knee arthroplasty using a posterior stablised prosthesis implanted via an anteromedial approach. Persistent pain which developed over more than six months led these patients to consult. Several surgeons evoked a “classical” cause of postoperative pain resulting from postoperative loosening but the x-ray and scintigraphy findings were inconclusive. Physical examination demonstrated dysaesthesia in the lateral infra-pateller region with a positive Tinel sign on the anteromedial aspect of the knee immediately below the tibial implant suggestive of a neurinoma of the infrapatellar branch of the saphenous nerve. An anatomic study conducted on ten knees enabled us to identify the anatomic bases necessary to achieve local anaesthesic blocks providing the pretherapeutic diagnosis. The diagnostic tests were performed with injection of 5 ml xylocaine in the subcutaneous tissue over the medial aspect of the knee upstream from the suspected neurinoma. Complete resolution of pain evaluated 10 minutes after injection led to proposing neurotomy of the infra-patellar nerve via a separate medial incision.

Results: Denervation provided immediate relief in three patients. For two, the pain and dysaesthesia regressed completely. Substantial improvement in hyperaesthesia was noted in one patient.

Discussion: The anatomic studies demonstrated that one or more branches of the infra-patellar nerve cross the mid line from the apex of the patella to the anterior tibial tuberosity in 98% of the cases. In ongoing work during revision procedures for total knee arthroplasty, we have noted hypoaesthesia or anaesthesia in the infra-patellar nerve territory in 15% of the patients. Dell reported a series of 70 patients with postoperative neurinomas of the knee and obtained 86% good results after denervation.

Conclusion: Hyperalgic iatrogenic neurinoma of an infra-patellar branch of the saphenous nerve is a certain but rare cause of pain after knee surgery, generally for prosthesis. Misdiagnosis of a mechanical complication is not uncommon. The clinically suggested diagnosis is easy to confirm by a subcutaneous local anaesthesia test. Neurotomy of the infra-patellar nerve can be proposed after failure of drug and physical treatments.