Case 1
The patient was an 11-year-old girl with a 1-year history of left coxalgia that had gradually worsened over time and made walking difficult. She was brought to our hospital for evaluation. There was no history of coxalgia, claudication, trauma, DDH, or generalized joint laxity, and she had not actively participated in sports.
The range of motion in her hip joints at the initial consultation (lt/rt) was 120/120 degrees of flexion, 20/40 degrees of abduction, 30/40 degrees of internal rotation, 30/40 degrees of external rotation, and 10/10 degrees of adduction. On abduction, internal rotation, and external rotation, the range of motion was limited. The flexion, abduction, and internal rotation (FADIR) test demonstrated negative reactions in bilateral hips.
Plain X-ray revealed the disappearance of the Y cartilage, joint space narrowing in the left hip, and acetabular/femoral head osteosclerosis. The lateral center-edge angle (LCEA) (lt/rt), Tönnis angle, and Sharp’s angle were 25/25, 10/10, and 45/45 degrees, respectively. The head–neck offset ratio was 0.25. The alpha angle was 39 degrees. There was no disruption of Shenton’s line, and no acetabular retroversion, cross-over sign, pistol grip deformity, or herniation pit on either side (Fig. 1a).
Computed tomography (CT) revealed joint space narrowing of the left hip, and osteosclerosis of the lateral superior anterior acetabulum and anterolateral femoral head, as observed on plain X-ray. In addition, subcartilaginous cysts in the acetabulum and femoral head were detected. The anterior center edge angle (ACEA) for the evaluation of acetabular coverage (lt/rt) was 50/50. The femoral neck shaft angle (lt/rt) was 130/130 degrees, and the angle of anteversion of the femoral neck (lt/rt) was 45/35 degrees [9] (Fig. 2). A subcartilaginous cyst in the left femoral head was observed on magnetic resonance imaging (MRI), as noted on CT. However, there was no necrosis of the femoral head (Fig. 3). There were no abnormalities in the blood test.
A diagnosis of unilateral premature OA of the left hip with excessive anteversion of the femoral neck was made. As osteoarthritis was severe, surgery was selected. To improve hip conformity, reduce anteversion of the femoral neck, and alter the weighted surfaces of the acetabulum and femoral head, proximal femoral flexional derotation varus osteotomy (PFFDVO) (flexion: 20 degrees, detorsion: 20 degrees, inversion: 20 degrees) and triple pelvic osteotomy (TPO) [10] were performed for the following reasons. Firstly, hip conformity on extension/internal rotation/abduction was favorable. Secondary, osteosclerosis and degeneration of the lateral superior anterior acetabulum was observed, so we added TPO.
After surgery, the surgical side was fixed with a hip spica cast for 6 weeks (Fig. 1b). For 1 year after the surgery, non-weight-bearing walking using a crutch was promoted. Plain X-ray 1 year after the surgery confirmed improvements in joint space narrowing of the left hip and acetabular/femoral head osteosclerosis. Full-weight-bearing walking was then initiated (Fig. 1c).
2 years after the surgery, coxalgia resolved and implant removal was performed (Fig. 1d). The range of motion (lt/rt) was 120/120 degrees on flexion, 30/40 degrees on abduction, 40/40 degrees on internal rotation, 40/40 degrees on external rotation, and 10/10 degrees on adduction, demonstrating improvement. Walking was possible; however, a difference in the leg length was identified, with the affected side lower limb approximately 3 cm shorter than the unaffected side lower limb.
Case 2
The patient was a 13-year-old girl. She was brought to our hospital with left coxalgia and claudication. She had fallen 2 months previously, and the gluteal region was bruised. However, no abnormality was noted on plain X-ray, and pain disappeared after 1 month. Before this episode, there was no history of coxalgia, claudication, DDH, or generalized joint laxity. Concerning sports, she had played tennis for the previous year.
The range of motion in her hips at the initial consultation (lt/rt) was 90/120 degrees on flexion, 30/40 degrees on abduction, 40/40 degrees on internal rotation, 20/40 degrees on external rotation, and 15/15 degrees of adduction. On abduction and external rotation, the range of motion was limited, and the FADIR test demonstrated negative reactions in bilateral hips.
Plain X-ray revealed the disappearance of the Y cartilage, irregularity of the left anterolateral femoral head, and a subcartilaginous cyst. The LCEA (lt/rt), Tonnis angle, and Sharp’s angle were 25/25, 10/10, and 45/45 degrees, respectively. The head–neck offset ratio was 0.22. And the alpha angle was 39 degrees. There was no disruption of Shenton’s line, or acetabular retroversion, cross-over sign, pistol grip deformity, or herniation pit on either side (Fig. 4a).
CT revealed irregularity of the left anterolateral femoral head and a subcartilaginous cyst. The anterior center edge angle (ACEA) for the evaluation of acetabular coverage (lt/rt) was 53/58. The femoral neck shaft angle (lt/rt) was 130/130 degrees, and the anteversion angle of the femoral neck (lt/rt) was 30/20 degrees [9] (Fig. 5). Necrosis of the femoral head was not found on MRI, but a subcartilaginous cyst in the femoral head and edema were observed (Fig. 6). There were no abnormalities in the blood test.
A diagnosis of unilateral premature osteoarthritis of the left hip with excessive anteversion of the femoral neck was made. She was prohibited from playing sports and prescribed rest. Pain decreased after 1 month, and there was no limit in the range of motion in the left hip; however, coxalgia recurred 1 year and 6 months after the initial consultation. The range of motion in her hips (lt/rt) was 30/120 degrees on flexion, 10/40 degrees on abduction, 20/40 degrees on internal rotation, 20/40 degrees on external rotation, and 15/15 degrees of adduction. On abduction, internal rotation, and external rotation, the range of motion was limited, and surgery was selected. Plain X-ray demonstrated joint space narrowing and osteosclerosis of the femoral head. As hip conformity on extension/internal rotation/abduction was favorable, PFFDVO (flexion: 20 degrees, detorsion: 20 degrees, inversion: 20 degrees) was performed to improve hip conformity, reduce anteversion of the femoral neck, and alter the weighted surface of the femoral head. In addition, we resected bone spurs on the femoral head because flexion was limited owing to the presence of osteophytes on the anterior femoral head. Acetabular osteotomy was not added because there was little osteosclerosis of the acetabulum, and the patient wanted to be discharged early.
After surgery, non-weight-bearing walking with a crutch was promoted (Fig. 4b). Plain X-ray confirmed improvements in joint space narrowing and osteosclerosis of the femoral head 1 year after surgery, at which time, full-weight-bearing walking was initiated (Fig. 4c).
1.5 years after the surgery, coxalgia resolved and implant removal was performed (Fig. 4d). The range of motion (lt/rt) was 90/120 degrees on flexion, 20/40 degrees on abduction, 20/40 degrees on internal rotation, 20/40 degrees on external rotation, and 15/15 degrees of adduction, demonstrating improvements. Walking became possible; however, range-of-motion limits remained (flexion: 90 degrees, abduction: 20 degrees, internal rotation: 20 degrees, external rotation: 20 degrees).