Impingement adversely affects 10-year survivorship after periacetabular osteotomy for DDH

Abstract

Background: Although periacetabular osteotomy (PAO) for developmental dysplasia of the hip (DDH) provides conceptual advantages compared with other osteotomies and reportedly is associated with joint survivorship of 60% at 20 years, the beneficial effect of proper acetabular reorientation with concomitant arthrotomy and creation of femoral head-neck offset on 10-year hip survivorship remains unclear.

Questions/purposes: We asked the following questions: (1) Does the 10-year survivorship of the hip after PAO improve with proper acetabular reorientation and a spherical femoral head; (2) does the Merle d'Aubigné-Postel score improve; (3) can the progression of osteoarthritis (OA) be slowed; and (4) what factors predict conversion to THA, progression of OA, or a Merle d'Aubigné-Postel score less than 15 points?

Methods: We retrospectively reviewed 147 patients who underwent 165 PAOs for DDH with two matched groups: Group I (proper reorientation and spherical femoral head) and Group II (improper reorientation and aspherical femoral head). We compared the Kaplan-Meier survivorship, Merle d'Aubigné-Postel scores, and progression of OA in both groups. A Cox regression analysis (end points: THA, OA progression, or Merle d'Aubigné-Postel score less than 15) was performed to detect factors predicting failure. The minimum followup was 10 years (median, 11 years; range, 10-14 years).

Results: An increased survivorship was found in Group I. The Merle d'Aubigné-Postel score did not differ. Progression of OA in Group I was slower than in Group II. Factors predicting failure included greater age, lower preoperative Merle d'Aubigné-Postel score, and the presence of a Trendelenburg sign, aspherical head, OA, subluxation, postoperative acetabular retroversion, excessive acetabular anteversion, and undercoverage.

Conclusions: Proper acetabular reorientation and the creation of a spherical femoral head improve long-term survivorship and decelerate OA progression in patients with DDH.

Fig. 1A–C

The current technique of periacetabular osteotomy is shown. (A) Typically, dysplastic hips present with an aspherical femoral head (asterisk). Before PAO, this decreased head-neck offset is compensated by the diminished anterior acetabular coverage. (B) After proper reorientation, femoroacetabular impingement may become apparent in deep flexion and internal rotation (arrow). Iatrogenic acetabular overcoverage can increase this conflict. (C) Through an intraoperative arthrotomy, the FAI conflict can be assessed. If necessary, a concomitant osteochondroplasty of the femoral neck can be performed.

Fig. 2

The definition of differing degrees of acetabular coverage is shown. The total femoral coverage is defined as the craniocaudal coverage of the femoral head by the acetabular rim (A). The anterior acetabular coverage is defined as the amount of coverage of the femoral head by the anterior acetabular wall in the AP direction (B). The posterior acetabular coverage is defined as the amount of coverage of the femoral head by the posterior acetabular wall in the posteroanterior direction (C).

Fig. 3

The Kaplan-Meier survivor analysis is shown for both groups with the end points defined as a conversion to THA, progression of OA, or a Merle d’Aubigné-Postel score of less than 15. Group I was comprised of all the hips with optimal acetabular reorientations and corrected or a priori spherical femoral heads. Group II was comprised of the hips with suboptimal acetabular reorientations and/or aspherical heads.

Fig. 4A–D

The radiographs of a 24-year-old woman from Group I (optimal acetabular retroversion and spherical femoral head) are shown. (A) The preoperative AP radiograph showed deficient lateral coverage. (B) Femoral head-neck offset was decreased in the preoperative crosstable view. At the 10-year followup the patient presented with a Merle d’Aubigné-Postel score of 17 points. (C) The AP radiograph showed sufficient lateral coverage and corrected version of the acetabulum without signs of progression of OA. (D) The decreased head-neck offset was corrected by performing an osteochondroplasty of the femoral head-neck junction, leading to impingement-free ROM.

Fig. 5A–F

(A) A 32-year-old woman from Group II presented with bilateral hip dysplasia. (B) The preoperative version of both acetabula is correct: the anterior wall (blue) does not cross the posterior wall (red). (C) The postoperative radiograph shows suboptimal acetabular reorientation on both sides (6 months postoperatively). (D) The right hip presents with excessive anteversion while the left hip presents with excessive retroversion. (E) Eight years after surgery, the right hip had severe progression of osteoarthritis. (F) In the left hip, a herniation pit formed as a result of iatrogenic pincer-type femoroacetabular impingement (arrow). The recurrent impingement resulted in joint space narrowing and subluxation of the joint. The patient required THA on the right side 9 years postoperatively and on the left side 12 years after surgery (not shown).