One-third of Hips After Periacetabular Osteotomy Survive 30 Years With Good Clinical Results, No Progression of Arthritis, or Conversion to THA

Abstract

Background: Since its first description in 1984, periacetabular osteotomy (PAO) has become an accepted treatment for hip dysplasia. The 30-year survivorship with this procedure has not been reported. Because these patients are often very young at the time of surgery, long-term followup and identification of factors associated with poor outcome could help to improve patient selection.

Questions/purposes: Looking at the initial group of patients with hip dysplasia undergoing PAO at the originator's institution, we asked: (1) What is the cumulative 30-year survival rate free from conversion to THA, radiographic progression of osteoarthritis, and/or a Merle d'Aubigné-Postel score < 15? (2) Did hip function improve and pain decrease? (3) Did radiographic osteoarthritis progress? (4) What are the factors associated with one or more of the three endpoints: THA, radiographic progression of osteoarthritis, and/or Merle d'Aubigné-Postel score < 15?

Methods: We retrospectively evaluated the first 63 patients (75 hips) who underwent PAO for hip dysplasia between 1984 and 1987. At that time, hip dysplasia was the only indication for PAO and no patients with acetabular retroversion, the second indication for a PAO performed today, were included. During that period, no other surgical treatment for hip dysplasia in patients with closed triradiate cartilage was performed. Advanced osteoarthritis (≥ Grade 2 according to Tönnis) was present preoperatively in 18 hips (24%) and 22 patients (23 hips [31%]) had previous femoral and/or acetabular surgery. Thirty-nine patients (42 hips [56%]) were converted to a THA and one patient (one hip [1%]) had hip fusion at latest followup. Two patients (three hips [4%]) died from a cause unrelated to surgery 6 and 16 years after surgery with an uneventful followup. From the remaining 21 patients (29 hips), the mean followup was 29 years (range, 27-32 years). Of those, five patients (six hips [8%]) did not return for the most recent followup and only a questionnaire was available. The cumulative survivorship of the hip according to Kaplan-Meier was calculated if any of the three endpoints, including conversion to THA, progression of osteoarthritis by at least one grade according to Tönnis, and/or a Merle d'Aubigné-Postel score < 15, occurred. Hip pain and function were assessed with Merle d'Aubigné-Postel score, Harris hip score, limp, and anterior and posterior impingement tests. Progression of radiographic osteoarthritis was assessed with Tönnis grades. A Cox regression model was used to calculate factors associated with the previously defined endpoints.

Results: The cumulative survivorship free from conversion to THA, radiographic progression of osteoarthritis, and/or Merle d'Aubigné-Postel score < 15 was 29% (95% confidence interval, 17%-42%) at 30 years. No improvement was found for either the Merle d'Aubigné-Postel (15 ± 2 versus 16 ± 2, p = 0.144) or Harris hip score (83 ± 11 versus 85 ± 17, p = 0.602). The percentage of a positive anterior impingement test (39% versus 14%, p = 0.005) decreased at 30-year followup, whereas the percentage of a positive posterior impingement test (14% versus 3%, p = 0.592) did not decrease. The percentage of positive limp decreased from preoperatively 66% to 18% at 30-year followup (p < 0.001). Mean osteoarthritis grade (Tönnis) increased from preoperatively 0.8 ± 1 (0-3) to 2.1 ± 1 (0-3) at 30-year followup (p < 0.001). Ten factors associated with poor outcome defined as THA, radiographic progression of osteoarthritis, and/or Merle d'Aubigné-Postel score < 15 were found: preoperative age > 40 years (hazard ratio [HR] 4.3 [3.7-4.9]), a preoperative Merle d'Aubigné-Postel score < 15 (HR 4.1 [3.5-4.6]), a preoperative Harris hip score < 70 (HR 5.8 [5.2-6.4]), preoperative limp (HR 1.7 [1.4-1.9]), presence of a preoperative positive anterior impingement test (HR 3.6 [3.1-4.2]), presence of a preoperative positive posterior impingement test (HR 2.5 [1.7-3.2]), a preoperative internal rotation of < 20° (HR 4.3 [3.7-4.9]), a preoperative Tönnis Grade > 1 (HR 5.7 [5.0-6.4]), a postoperative anterior coverage > 27% (HR 3.2 [2.5-3.9]), and a postoperative acetabular retroversion (HR 4.8 [3.4-6.3]).

Conclusions: Thirty years postoperatively, 29% of hips undergoing PAO for hip dysplasia can be preserved, but more than 70% will develop progressive osteoarthritis, pain, and/or undergo THA. Periacetabular osteotomy is an effective technique to treat symptomatic hip dysplasia in selected and young patients with closed triradiate cartilage. Hips with advanced joint degeneration (osteoarthritis Tönnis Grade ≥ 2) should not be treated with PAO. Postoperative anterior acetabular overcoverage or postoperative acetabular retroversion were associated with decreased joint survival.

Level of evidence: Level III, therapeutic study.

Fig. 1

Patient selection for the 30-year PAO followup study is shown. *Died unrelated to surgery with an uneventful followup 6 and 16 years after surgery; ^†patients did not return for 30-year followup but returned a questionnaire with clinical scores. These patients had a last clinical and radiographic followup at 11 to 21 years after surgery.

Fig. 2

Survival rate of hips after PAO up to a followup of 30 years is shown. Endpoints were defined as conversion to THA, progression of osteoarthritis, and a Merle d’Aubigné-Postel [8] score of < 15. Values are expressed as cumulative survivorship with 95% confidence interval (CI) in parentheses for each 10-year interval.

Fig. 3

The distribution of preoperative osteoarthritis according to the Tönnis grades [51] in hips undergoing PAO is shown. At 30-year followup, the progression of osteoarthritis or conversion to THA depending on the preoperative grade of osteoarthritis is displayed.

Fig. 4A–C

Survivorship rate at 30 years was dependent on different factors associated with endpoints (THA, progression of osteoarthritis [OA], and a Merle d’Aubigné-Postel score < 15). (A) In hips with an age at operation < 20 years, survival was 56% at 30 years, whereas no hip survived at 30 years with a preoperative age > 45 years. (B) Hips with no preoperative osteoarthritis had a survival rate of 42% at 30 years compared with 8% of hips with a preoperative osteoarthritis score according to Tönnis Grade ≥ 2. (C) Forty-seven percent of hips with a preoperative HHS > 90 survived 30 years compared with 4% in hips with a HHS < 70.

Fig. 5A–E

(A) A 15-year-old female patient presented with hip dysplasia and subluxation of the joint (broken Shenton’s line). (B) PAO to increase femoral head coverage was performed. At 10-year (C), 20-year (D), and 30-year followup (E), the joint space was well preserved and the patient presented without hip pain (Merle d’Aubigné-Postel score 18).

Fig. 6A–E

(A) A 28-year-old woman presented with hip dysplasia with preserved joint space. (B) Twelve years later the patient presented with complete joint space narrowing and cystic changes of the femoral head. (C) Despite the preoperative degeneration of the joint, PAO was performed to improve femoral head coverage. Joint space width improved after surgery. (D) At 13-year followup after PAO, the joint showed marked progression of osteoarthritis and (E) conversion to THA was performed.

Fig. 7

The bubble chart shows the followup time, size of the study in terms of number of patients included (size of bubble), treatment (color), and survival rate with conversion to THA as the only endpoint of selected literature [–, , , , –, , , , , –, , , , , –54, 56, 57] for pelvic osteotomies in hips with dysplasia. The gray line represents the survivorship of THAs performed in female patients younger than 50 years of age from the Swedish Hip Registry [10] for comparison with the pelvic osteotomies.