Developing a Computer Vision Model to Automate Quantitative Measurement of Hip-Knee-Ankle Angle in Total Hip and Knee Arthroplasty Patients.

BACKGROUND: Increasing deformity of the lower extremities, as measured by the hip-knee-ankle angle (HKAA), is associated with poor patient outcomes after total hip and knee arthroplasty (THA, TKA). Automated calculation of HKAA is imperative to reduce the burden on orthopaedic surgeons. We proposed a detection-based deep learning (DL) model to calculate HKAA in THA and TKA patients and assessed the agreement between DL-derived HKAAs and manual measurement. METHODS: We retrospectively identified 1,379 long-leg radiographs (LLRs) from patients scheduled for THA or TKA within an academic medical center. There were 1,221 LLRs used to develop the model (randomly split into 70% training, 20% validation, and 10% held-out test sets); 158 LLRs were considered "difficult," as the femoral head was difficult to distinguish from surrounding tissue. There were 2 raters who annotated the HKAA of both lower extremities, and inter-rater reliability was calculated to compare the DL-derived HKAAs with manual measurement within the test set. RESULTS: The DL model achieved a mean average precision of 0.985 on the test set. The average HKAA of the operative leg was 173.05 ± 4.54°; the nonoperative leg was 175.55 ± 3.56°. The inter-rater reliability between manual and DL-derived HKAA measurements on the operative leg and nonoperative leg indicated excellent reliability (intraclass correlation (2,k) = 0.987 [0.96, 0.99], intraclass correlation (2, k) = 0.987 [0.98, 0.99, respectively]). The standard error of measurement for the DL-derived HKAA for the operative and nonoperative legs was 0.515° and 0.403°, respectively. CONCLUSIONS: A detection-based DL algorithm can calculate the HKAA in LLRs and is comparable to that calculated by manual measurement. The algorithm can detect the bilateral femoral head, knee, and ankle joints with high precision, even in patients where the femoral head is difficult to visualize.

Management of Dorsal Bunion in Nonambulatory Adolescents with Cerebral Palsy: A Retrospective Cohort Study.

BACKGROUND: A dorsal bunion may occur in nonambulatory adolescents with cerebral palsy (CP) and a Gross Motor Function Classification System (GMFCS) level of IV or V. The deformity can cause pain, skin breakdown, and difficulty wearing shoes and braces. A consensus on the biomechanics and surgical management of dorsal bunions in persons with severe CP has not been established. METHODS: This retrospective cohort study included 23 nonambulatory adolescents with CP, GMFCS level IV or V, and symptomatic dorsal bunions requiring surgery. The median age at surgery was 17 years, and the median follow-up was 56 months. Reconstructive surgery included the excision of a 2 to 3-cm segment of the tibialis anterior tendon to correct the elevation of the first metatarsal. The fixed deformity of the first metatarsophalangeal joint was managed with use of corrective arthrodesis and dorsal plate fixation. Clinical and radiographic outcomes were assessed preoperatively and postoperatively at the transition to adult services. RESULTS: There were significant improvements in the clinical and radiographic outcome measures (p < 0.001). Pain was relieved, and there were no further episodes of skin breakdown. The elevation of the first metatarsal was corrected from a mean of 3° of dorsiflexion to a mean of 19° of plantar flexion. The deformity of the first metatarsophalangeal joint was corrected from a mean of 55° of plantar flexion to a mean of 21° of dorsiflexion. Six patients had complications, all of which were grade I or II according to the modified Clavien-Dindo system. CONCLUSIONS: The surgical reconstruction of a dorsal bunion via soft-tissue rebalancing of the first ray and corrective arthrodesis of the first metatarsophalangeal joint resulted in favorable medium-term clinical and radiographic outcomes in nonambulatory adolescents with CP. LEVEL OF EVIDENCE: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.