Conventional computer navigation systems using bone fixation have been validated in measuring anteroposterior (AP) translation of the tibia. Recent developments in non-invasive skin-mounted systems may allow quantification of AP laxity in the out-patient setting.

We tested cadaveric lower limbs (n=12) with a commercial image free navigation system using passive trackers secured by bone screws. We then tested a non-invasive fabric-strap system. The lower limb was secured at 10° intervals from 0° to 60° knee flexion and 100N of force applied perpendicular to the tibial tuberosity using a secured dynamometer. Repeatability coefficient was calculated both to reflect precision within each system, and demonstrate agreement between the two systems at each flexion interval. An acceptable repeatability coefficient of ≤3mm was set based on diagnostic criteria for ACL insufficiency when using other mechanical devices to measure AP tibial translation.

Precision within the individual invasive and non-invasive systems measuring AP translation of the tibia was acceptable throughout the range of flexion tested (repeatability coefficient ≤1.6 mm). Agreement between the two systems was acceptable when measuring AP laxity between full extension and 40° knee flexion (repeatability coefficient ≤2.1 mm). Beyond 40° of flexion, agreement between the systems was unacceptable (repeatability coefficient >3 mm).

These results indicate that from full knee extension to 40° flexion, non-invasive navigation-based quantification of AP tibial translation is as accurate as the standard invasive system, particularly in the clinically and functionally important range of 20° to 30° knee flexion. This could be useful in diagnosis and post-operative follow-up of ACL pathology.

ACL (anterior cruciate ligament) partial tears include various types of lesions, and an high rate of these lesions evolve into complete tears. Most of the techniques described in literature for the surgical treatment of chronic partial ACL tears, don't spare the intact portion of the ligament. Aim of this study was to perform a prospective analysis of the results obtained by augmentation surgery using gracilis and semitendinosus tendons to treat partial sub-acute lesions of the ACL. This technique requires an “over the top” femoral passage, which enables salvage and strengthening of the intact bundle of ACL. The study included 97 patients treated consecutively at our Institute from 1993 to 2004 with a mean injury-surgery interval of 23 weeks (12–39). Patients were followed up by clinical and instrumental assessment criteria at 3 months, 1 year and 5 years after surgery. Clinical assessment was performed with the IKDC form. Subjective and functional parameters were assessed by the Tegner activity scale. Instrumental evaluation was done using the KT-2000 instrument: the 30 pound passive test and the manual maximum displacement test were performed. We obtained good to excellent results in 95.9% of cases. We didn't observed recurrences in ligamentous laxity. We believe that the described technique has the advantage of being little invasive, compatible with the ACL anatomy, and enables very rapid functional recovery and return to sport

Introduction. The legion knee revision system was designed as a follow and improvement to the Genesis II knee system- allowing for a surgeon directed femoral rotation as opposed to the in-built femoral rotation in the previous system. This is a prospective review of consecutive patients who underwent knee revision surgery using the legion knee system. Methods. Clinical and functional assessments were carried out preoperatively, one year and 2 years post op. Radiographic evaluation was done at 1 and 2years follow up. Standard knee scoring systems (American Knee Scores-AKS, and Oxford score were used for the clinical and functional evaluation of these patients. The WOMAC score was also used to assess for pain, stiffness and social function in these patients. The radiographic assessment included review of standing AP, lateral and skyline views. Figgie's method was used to measure the joint line reproduction. A difference of 5 mm (pre = op/post-op) was deemed satisfactory. Results. Seventy-five consecutive patients underwent revision knee system- 38 male: 34 females with a mean age of 71.2 (50–87 yrs.). Mean BMI-26.03, (Range 11–50). We had a 2-year follow up for 32 patients Surgery was carried out at a single centre and performed by members of the Bristol knee group. Indications for surgery in these patients- were aseptic loosening (38), instability (15), pain and stiffness (7), polyarthropathy (2), ligament laxity (3), peri-prosthetic fractures (3), and impingement (4). The mean American Knee scores, and WOMAC scores at, 1 year and 2 years follow up showed significant improvements in pain and function. It was also noted that the mean oxford knee score improved from 14/48 pre-operatively to 34/48 at 2yrs. Radiographic assessment showed a mean AP coronal femoral angle of 95.3 degrees (range 89.6–99.9 degrees), coronal tibial angle of 90.1 degrees (Range 88–92 degrees). The mean sagittal femoral and tibial angles were 88.4 and 90.4 degrees respectively. Mean Kappa value for the inter observer reliability for the radiographic assessment was 0.50 showing agreement, with standard error measurement of 1.2. The joint line was reproduced in all cases. Discussion. The short-term results with the Legion Knee revision system showed significant improvement in functional and pain scores in these patients irrespective of their indications for revision surgery. Overall the legion system has showed good outcome scores that match or beat published series on revisions. It also showed a good ability to restore joint line. Ongoing work needed to refine indications and realistic outcomes for different diagnoses