A primary goal of revision Total Knee Arthroplasty (rTKA) is restoration of the Joint Line (JL) and Posterior Condylar Offsets (PCO). The presence of a native contralateral joint allows JL and PCO to be inferred in a way that could account for patient-specific anatomical variations more accurately than current techniques. This study assesses bilateral distal femoral symmetry in the context of defining targets for restoration of JL and PCO in rTKA. 566 pre-operative CTs for bilateral TKAs were segmented and landmarked by two engineers. Landmarks were taken on both femurs at the medial and lateral epicondyles, distal and posterior condyles and hip and femoral centres. These landmarks were used to calculate the distal and posterior offsets on the medial and lateral sides (MDO, MPO, LDO, LPO respectively), the lateral distal femoral angle (LDFA), TEA to PCA angle (TEAtoPCA) and anatomic to mechanical axis angle (AAtoMA). Mean bilateral differences in these measures were calculated and cases were categorised according to the amount of asymmetry. The database analysed included 54.9% (311) females with a mean population age of 68.8 (±7.8) years. The mean bilateral difference for each measure was: LDFA 1.4° (±1.0), TEAtoPCA 1.3° (±0.9), AAtoMA 0.5° (±0.5), MDO 1.4mm (±1.1), MPO 1.0mm (±0.8). The categorisation of asymmetry for each measure was: LDFA had 39.9% of cases with <1° bilateral difference and 92.4% with <3° bilateral difference, TEAtoPCA had 45.8% <1° and 96.6% <3°, AAtoMA had 85.7% <1° and 99.8% <3°, MDO had 46.2% <1mm and 90.3% <3mm, MPO had 57.0% <1mm and 97.9% <3mm. This study presents evidence supporting bilateral distal femoral symmetry. Using the contralateral anatomy to obtain estimates for JL and PCO in rTKA may result in improvements in intraoperative accuracy compared to current techniques and a more patient specific solution to operative planning.
Medical and allied health staff are beginning to incorporate the Nintendo Wii-Fit into musculoskeletal rehabilitation protocols. One potential application is the assessment of standing balance following Orthopaedic lower limb surgery. The Wii Balance Board (WBB) has been shown to be a valid equivalent to a laboratory grade force platform for the assessment of standing balance. Our objective was to investigate the validity and reliability of the balance tests included with the Wii-Fit software. Initially, a single subject performed multiple repeats of a standing balance test. The data was collected simultaneously from a commercial force platform using its integrated software that measured centre of pressure and from the WBB using the Wii-Fit software that generated a percentage score. The data from each was compared and analyzed, applying the equations of known, validated standing balance measurements. Then, thirty subjects free of lower limb pathology performed a series of standing balance tests combining single leg and double leg stance with their eyes open and then closed. Data was collected from one set of trials on the WBB using the Wii-Fit software and another using bespoke centre of pressure software on a laptop computer. The tests were then repeated on a second occasion within 2 weeks. The algorithm used by the Wii-Fit software to generate the ‘Stillness’ standing balance score was calculated with a predictive value (R squared) of 0.94. This correlated well to a known, valid measure of standing balance. Test-retest reliability was examined for the data from both pieces of software. Both demonstrated good-to-excellent test-retest reliability within ‘software’. The laptop data was transformed using the algorithm and the between ‘software’ reliability was calculated as good-to-excellent. The Wii-Fit software collects standing balance data from the WBB at a fraction of the cost of laboratory grade systems. The score generated by the Wii-Fit software is reliable and valid as an overall assessment of standing balance. Although its application would be limited for detailed assessment of balance disorders, it could still provide surgeons with an affordable, clinic based balance-screening tool. This could form part of an assessment protocol following lower limb surgery.
The AMMFL is an anatomical variant of the attachment of the anterior horn of the medial meniscus to the posterolateral wall of the intercondylar notch. It is distinct from the meniscofemoral ligaments of Wrisberg and Humphrey. This large series prospectively documented its incidence and any associated meniscal or chondral pathology. The study period was from September 2006 until December 2007. All patients that underwent arthroscopy of the knee for meniscal, chondral or ligamentous pathology including arthroscopic anterior cruciate ligament reconstruction were included. The procedures were performed by the two senior authors, according to their standard protocols at one of two hospitals. All the findings from the arthroscopies were prospectively recorded in a standardized datasheet. This recorded all meniscal, chondral and miscellaneous pathology including the presence or absence of an AMMFL. This data was entered into a database including all patients. The results of 401 arthroscopic procedures were recorded during the study period. Of these patients, 14 were found to have AMMFLs, resulting in an incidence of 3.49%, higher than previously reported. ( The associated pathology was most commonly a radial tear of the medial meniscus, found in six patients. One had a bucket handle tear of the medial meniscus. There were three lateral meniscus tears, two of which were associated with an ACL rupture. Two patients had an ACL rupture as the only other pathology at arthroscopy. One patient was found to have a ruptured AMMFL as her only pathology. This anatomical variant is more common in this Australian sample than has been described in the literature, and there seems to be a relationship between the presence of the AMMFL and a particular pattern of medial meniscus tear, suggesting an influence of this anatomical variant on meniscal pathology.
