Purpose of the study: Reconstruction of the anterior cruciate ligament (ACL) controls laxity but does not enable restoration of strictly normal 3D kinematics. The purpose of this study was to compare the kinematics of the pathological knee with that of the healthy knee after ACL plasty. This study applied a new ambulatory system using miniature captors.

Material and method: Five patients with an isolated injury of the ACL participated in this study. The patients were assessed after injury (T1), at five months (T2), and at 14 months (T3) after surgery. The assessment included laxity (KT-1000), the IKDC score and the Lysholm score. The 3D angles of the knees were measured when walking 30 m on flat ground using a system composed of to small inertia units (3D accelerometer and 3D gyroscope) and a portable recorder. Functional settings were optimised and validating to ensure easy precise measurement of the 3D angles. Symmetry of the two knees was quantified using a symmetry index (SI) (difference in amplitude normalised in relation to mean amplitude) and the correlation coefficient CC.

Results: Clinical indicators improved during the follow-up (IKDC T1: 3C, 2C; T2: 5B; T3: 2A, 3B; subjective IKD: 53–95; Lysholm 67–96). Mean laxity improved from 8.6m to 2.5 mm. The gait analysis showed increased symmetry in terms of amplitude for flexion-extension (SI: −17% at T1, −1% at T2, 1% at T3), and an increase in symmetry in terms of the rotation signature (CC: 0.16 at T1, 0.99 at T2, 0.99 at T3). There was no trend to varus-valgus.

Discussion: This study demonstrates the clinical application of the new ambulatory system for measuring 3D angles of the knee joint. Joint symmetry increased after ACL plasty but still showed some perturbation at 14 months. The results observed here are in agreement with the literature. Other patients and other types of gait are being analysed.

Conclusion: This portable system allows gait analysis outside the laboratory, before and after ACL injury. It is very useful for follow-up after surgery.

Endoscopic methods of ACL reconstruction have shown some disadvantages such as the inability to freely position the femoral tunnel. Moreover, this technique dictates relatively vertical and central non anatomical graft placement compared to the more horizontal and lateral course of the native ACL. The ACL presents a collection of individual fibers that are grouping in two distinct bands, anteromedial (AM) and posterolateral (PL). The most anterior fibers of AM band are the most isometric. The majority of ACL fibers lie posteriorly to the isometric point on the medial wall of the femoral condyle. These fibers are lax during flexion and tight in extension. This behaviour was defined “favourable non isometry”. The “favourable non isometry” is very interesting because increased knee loading often occurs at flexion angles of less than 60 degrees. Classic two-incision technique, using a rear-entry drill, our two-incision technique, or the Clancy anatomic endoscopic technique using flexible reamers and use of different not commonly arthroscopic portals seems to allow a predictable, near-anatomic placement of femoral tunnel.

Purpose: Cyclope syndrome is a complication which occurs after ligamentoplasty of the anterior cruciate ligament. It is characterised by permanent flexion which may or not be associated with anterior pain, cracking or hydroarthrosis, typically during exercise. The diagnosis is confirmed by MRI. Arthroscopic treatment is indicated for resection of the nodule and as needed bone plasty of the notch if permanent flexion persists. In the literature, short-term results have been disappointing. We wanted to know more about the long-term outcome.

Material and methods: From January 1992 to December 1994, 835 patients underwent bone-tension plasty. Thirty-six underwent secondary surgery for cyclope syndrome (4.3%). Mean age at revision procedure was 26.2 years (16–43). Most of the subjects were athletes. Twenty-three patients (63.9%) were seen at follow-up consultation and 16.7% responded to a telephone interview. Mean time to review was nine years (8–10 years). We used the IKDC 1999 chart for subjective assessment and clinical evaluation and measured laxity with KT1000. We also studied changes in symptoms related to cyclope syndrome.

Results: We had two cases of recurrent tears (6.9%). The mean final subjective IKDC score was 81.6 points. Half of the patients had good outcome (> 82 points) and half had disappointing results (scored 50–80 points). The final objective IKDC scoring was: A=17.4%, B=65.2%, C=8.7%, D=8.7%. Thirteen patients had persistent signs of cyclope syndrome (44.8%). Fourteen still had limited joint motion (48.3%). Fifteen reduced their physical activity level (51.7%).

Discussion: The origin of the cyclope syndrome remains controversial. It is difficult to assess the risk of recurrent tear due to the small size of the population and the long time to review in this series.

Conclusion: Cyclope syndrome does not appear to be a factor of risk of laxity but is a non-negligible factor of morbidity, even ten years later. It appears to be important to operate early in order to avoid the spiral of chronic suffering. The postoperative flexion, which had been advocated in the past, does not appear to be useful.