A special surgical technique and consideration is necessary in the total hip arthroplasty for dysplastic osteoarthritis after Kalamchi and MacEwen Type III or IV deformity (so called “Perthes-like-deformity”). There have been few reports concerning the total hip arthroplasty for “Perthes-like-deformity”. We evaluated the clinical and radiological outcome of 52 uncemented hip arthroplasties for the lesion.

We have performed 106 hips of uncemented total hip arthroplasty for dysplastic osteoarthritis after Kalamchi and MacEwen Type III or IV deformity. Among them, 52 hips of 47 patients (11 males and 41 females) were evaluated with minimum of three years follow-up. The average age at the surgery was 52 (28 to 65). The average follow-up period was 4.8 (3 to 8.1) years. Against the developmental dysplasia or dislocation, 29 hips of 26 patients had been treated by casting or surgery in infancy. Thirteen hips of 11 patients had no previous treatment before the arthroplasty. Spongiosa metal cup (GHE: ESKA implants, Lübeck, Germany) was used for 33 hips of 28 patients and Zweymüller type cup (Allo-classic cup: Zimmer Inc., Warsaw, IN, Bicon cup: Smith & Nephew Orthopedics AG, Rotkreuz, Switzerland) for 19 hips of 19 patients. Spongiosa Metal stem (GHE: ESKA implants) was used for 23 hips of 19 patients and Zweymüller type stem (Alloclassic stem: Zimmer Inc., SL stem: Smith & Nephew Orthopedics AG) for 29 hips of 28 patients. The average operative time was 108 (53 to 233) minutes. The average blood loss during the surgery was 731(150 to 1749) milliliters. The adductor tendon release was added in 28 hips of 26 patients against the severe contracture. The patients were evaluated clinically (pre-surgical history, hip score, leg length discrepancy, Trendelenburg sign, and gait function) and radiologically (ATD before the surgery, alignment, and stability of implants). Average ATD before the surgery was −2.2 (−28 to 17) millimeters. The average leg length discrepancy was 1.9 (0 to 7) centimeters before the surgery and was improved to 0.1 (0 to 1) centimeters after the surgery. The average hip score was 54 (23 to 80) before the surgery and was improved to 90 (69 to 100) after the surgery. At the final follow-up, Trendelenburg sign was positive in 14 hips of 14 patients (26.9%) and the limping was not obvious in 38 hips of 33 patients (73.1%). All implants were stable at the final follow-up.

“Perthes-like-deformity” often has the severe deformity. It has a shortening or an absence of the neck and an excessive antetorsion of the femur. When it has the coxa magna, the acetabulum is shallow, has the narrow anteroposterior diameter, and has the thin wall like the osteophyte. It is frequently accompanied by shortening of leg and contracture, as the lesion arises from the development disorders. Thus, the total hip arthroplasty, especially uncemented one, is complicated. However, the satisfactory result can be obtained by careful consideration and surgical procedure such as a provision against the bleeding and the soft tissue release.

Considerable numbers of authors have reported the change in periprothetic bone mineral density (BMD) after hip arthroplasty. However, there have been few reports concerning the BMD in the lumbar vertebra, especially for dysplastic hips.

Since 1998, we have been measuring the BMD mineral density for 2016 patients by DXA (Dual-energy X-Ray Absorptionmetry method). Among them, we evaluated the BMD in 66 postmenopausal patients with the single side primary arthroplasty, with five years or more follow-up, and also aged 60 or more. We used a DXA densitometer (DPX-IQ, GE Healthcare, Madison, WI, USA). The diagnosis at the surgery was dysplastic osteoarthritis in all patients. The average age at the surgery was 66 (60–81). All patients were female. No patients had the systematic diseases which contributed to the secondary osteoporosis. No patients had received the pharmacotherapy for osteoporosis in the whole therapeutic process. The bed rest was seven from two days after the surgery (different by the operation date). The average follow-up was 7.0 (five to ten) years.

The average BMD in the lumbar vertebra before the surgery was 0.996 (0.612 to 1.712) g/cm2. The BMD was 0.971 (0.637 to 1.402) at six month postoperatively, 0.972 (0.552 to 1.740) at one year, 1.004 (0.573 to 1.733) at two years, 1.032 (0.633 to 1.670) at three years, 1.035(0.724 to 1.688) at four years, 1.031 (0.564 to 1.679) at five years, 1.027 (0.734 to 1.647) at six years, 1.042 (0.589 to 1.389) at seven years. At the final follow-up, the BMD was 1.054 (0.589 to 1.647). In 53 patients (80%), the density at the final follow-up increased in comparison to that before the surgery. In 27 patients (41%), the density once decreased six month postoperatively. The density increased at 3 years (t=−1.919, p=0.030), four years (t=−2.523, p=0.015), five years (t=−2.381, p=0.021), seven years (t=−2.822, p=0,007), and at the final-follow-up (−4.076, p= 0.000) in comparison to that before the surgery. The activity of the patients was evaluated by the hip score. The average score was 54.5 (21 to 76) before the surgery. The average score was 88.0 (66 to 100) and increased at the final follow-up in comparison to that before the surgery (t=−13.04, p 0.000).

Some authors (eg. Bergström I, 2008, Espar I, 2008, etc.) have pointed out that the appropriate activity may increase the bone density. Presumed from the literatures, the increase of activity after the arthroplasty may have increased the BMD, though the direct correlation was not obvious between the BMD and the amount of hip score (at the final follow-up: r=0.005, p=0.972) in this study.