The McMaster osteotomy—a novel surgical treatment to chronic slipped capital femoral epiphysis: description of surgical technique and case study

Slipped capital femoral epiphysis (SCFE) is a common adolescent hip disorder that can lead to complex proximal femur deformities and devastating consequences such as avascular necrosis, femoroacetabular impingement syndrome and early-onset osteoarthritis. Existing surgical techniques are often insufficient to fully address the constellation of multiplanar deformities in patients with severe SCFE. Therefore, the McMaster Osteotomy, a novel intertrochanteric proximal femur osteotomy, was developed to improve anatomic correction and hip mechanics in patients with chronic SCFE. The McMaster Osteotomy was implemented in two patients (A: 16-year-old male, B: 17-year-old female) with proximal femur deformities due to chronic SCFE. Surgical planning was facilitated with a 3D-printed pelvic model generated from a CT scan of a patient with the SCFE deformity. Patient B also underwent concurrent arthroscopic osteochondroplasty and labral repair. Pre- and post-operative function and radiographic measurements were recorded. Post-operatively, patient A's neck-shaft angle improved from 125° to 136°, Southwick angle from 52° to 33°, neck length from 66 mm to 80 mm and hip internal rotation from 5° to 25°. Patient B's post-operative neck-shaft angle improved from 122° to 136°, Southwick angle from 25° to 15°, neck length from 76 mm to 84 mm, hip internal rotation from 5° to 20° and alpha angle from 87.6° to 44.3°. Both patients are pain-free and have obtained full union of their osteotomies. The McMaster Osteotomy is a versatile technique that can produce a more anatomic reconstruction of hip anatomy and restoration of abductor mechanics. As an extracapsular technique, the risk of femoral head avascular necrosis is minimized.