Commentary & Perspective on
"Periacetabular Osteotomy Through a Modified Ollier Transtrochanteric Approach for Treatment of Painful Dysplastic Hips"
by Jih-Yang Ko, MD, et al.

Commentary & Perspective by
Reinhold Ganz, MD*,
Department of Orthopedic Surgery,
University of Bern, Bern, Switzerland

In this paper, Ko et al. described the operative technique for a periacetabular osteotomy with use of a modified Ollier transtrochanteric approach to the acetabulum. Over a period of eight years, the authors performed thirty-eight operations in thirty-six patients with painful dysplastic hips and reported satisfactory results for thirty-two hips (84%) at a follow-up of two to ten years (mean, five years and six months). Complications included prolonged limping (up to two years) in eleven hips, necrosis of the acetabulum in two, and heterotopic ossification, anterior impingement, and a defect on the rotated ilium in one hip each.

They concluded that use of their modified Ollier approach allowed the osteotomies to be executed under direct vision, thus preventing intra-articular penetration. They further claimed that vascularity of the acetabulum was better preserved with their modified surgical approach than with other rotational osteotomies. Finally, they stated that this procedure is less demanding, with virtually no learning curve, in comparison with most other acetabuloplasties.

It is certainly important to improve surgical techniques; however, we also must evaluate carefully the potential advance in light of preexisting orthopaedic knowledge and experience.

There is no doubt that the surgical techniques for reorientation of the acetabulum are technically demanding. In addition, each technique has relative strengths and weaknesses with regard to intraoperative visualization of the osteotomy, ability to align the hip joint and avoid anterior overcorrection, preservation of acetabular perfusion, and the possibility of performing an arthrotomy. Ko et al. outlined the related advantages and disadvantages of various periacetabular osteotomies in the introduction before proposing their own approach.

The study comprised thirty-eight hip procedures over a period of eight years, which amounts to an average annual rate of less than five operations, a frequency that seems to be rather low for mastery of such complex surgery. The authors tried to anticipate criticism related to this by documenting the lack of substantial differences between the results of the first and the second nineteen hips.

The authors used traditional methods of data collection and analysis, but I would recommend the inclusion of measurements of both the acetabular version¹ and the relative medial-lateral position of the acetabular fragment. The former is important because retroversion of the dysplastic acetabulum is common, and the latter, because most dysplastic acetabula are lateralized, and spherical osteotomies cannot readily medialize the acetabular fragment. Also, I do not understand the significance of the measurement of lateral subluxation that the authors provided.

The description of the modified Ollier approach leaves several questions unanswered. The authors recommended blunt splitting of the fibers of the gluteus maximus at the level of the posterior border of the gluteus medius, but this level can vary substantially according to the patient's muscle mass and/or the osseous morphology. Paradoxically, this level can be identified only after the split of the gluteus maximus is executed.

The statement that the osteotomized greater trochanter is turned proximally along with ‘part of the short external rotators’ is vague. Because the vascular supply to the femoral head may be endangered², more precise information about this step would be appreciated. The next questions pertain to the choice of landmarks for the cut of the posteroinferior part of the acetabulum. Only retraction of the quadratus femoris is mentioned, yet the obturator externus muscle is closer to the osseous surface, and the safe interval for protection of the deep branch of the medial femoral circumflex artery lies between the gemellus inferior and the obturator externus muscles². Finally, it is unclear how the iliopectineal eminence ("protuberance of the iliopubic bone") is approached. Perhaps the dissection to the bone is between the capsule and the capsular portion of the iliacus muscle since cutting of the iliopsoas tendon is mentioned. In any case, the preservation of the vascular bundle to the tensor fasciae latae should be mentioned when it is isolated medially and laterally.

Finally, there is no description of how the acetabular artery is preserved. This artery provides substantial blood supply to the inferior part of the acetabulum and, given the described technique, it may remain the only blood supply to the acetabulum together with the capsular vessels.

Parenthetically, it may be advantageous to harvest the bone graft from the inside of the iliac bone. This would avoid detachment of the origin of the tensor fasciae latae and/or gluteus medius muscles.

The results are somewhat confounded by the data on six patients with poliomyelitis. Four of these six apparently did not have involvement of the operated hip. Therefore, these four hips cannot be used in the calculation of a higher success rate when the poliomyelitis patients are excluded. The six patients with poliomyelitis were again included among the patients who had prolonged limping. It may be argued that prolonged limping is attributable not to poliomyelitis but to use of the extensile approach.

The authors repeatedly proposed that this procedure offers better vascularity to the acetabulum but offered no data to support this statement, and the issue of the vascular anatomy is not addressed at all. The two cases of necrosis of the acetabulum were attributed to a history of steroid therapy in one patient and alcoholism in the other, but the concern remains that the described technique does not substantially decrease the risk of avascular necrosis of the acetabulum when compared with other spherical osteotomies. Furthermore, I do not believe that this technique prevents the complication of intra-articular osteotomy. The hip joint is particularly vulnerable during osteotomy along the posterior column, where a misdirected osteotome may penetrate into the joint even when the periacetabular bone is sufficiently exposed.

In summary, the approach proposed by Ko et al. represents a laborious dissection with potential morbidity. There is no proof that this procedure protects the vascularity of the acetabular fragment better than do other spherical osteotomies.

*The author did not receive grants or outside funding in support of the research or preparation of this manuscript. He did not receive payments or other benefits or a commitment or agreement to provide such benefits from a commercial entity. No commercial entity paid or directed, or agreed to pay or direct, any benefits to any research fund, foundation, educational institution, or other charitable or nonprofit organization with which the author is affiliated or associated.

References

1. Reynolds D, Lucas J, Klaue K. Retroversion of the acetabulum. A cause of hip pain. J Bone Joint Surg Br. 1999;81;281-8.
2. Gautier E, Ganz K, Krügel N, Gill T, Ganz R. Anatomy of the medial femoral circumflex artery and its surgical implications. J Bone Joint Surg Br. 2000;82:679-83.