Reciting the words spoken by William Harris in 1986, orthopedic surgeons persist in their assertions that “Primary hip osteoarthritis (OA) is extremely rare.”1 These doctors continue to claim that “Up to 90% of young patients (<50 years of age) that develop OA of the hip have an underlying structural problem, which in half the cases is dysplasia.”2
A diagnosis of developmental dysplasia of the hip (DDH) is based on the center edge angle of Wiberg3, which is calculated from standard anterior-posterior (AP) radiographs. To obtain the CE angle, a vertical line is drawn through the center of the femoral head, and another to the lateral edge of the ‘sourcil’. (Figure 1)
The sourcil, a French term meaning ‘eyebrow’, is a projection of the anterior-superior acetabular wall. It is a 2-dimensional contrived parameter that the practice of orthopedics actually believes to be the load-bearing aspect of the acetabulum. In reality, the sourcil does not exist as reflected on pelvic x-rays. Its lateral edge, often used to diagnose ‘pincer impingement’, is subject to change with the slightest rotation of the pelvis, as more of the arched acetabular roof comes into view. (Figure 2)
Moreover, the entire AP radiograph, taken in the supine position, is a faulty representation of how the femoral heads are actually contained within the acetabulum. When supine, lumbar curvature flattens and the femoral heads move slightly up and laterally. When standing with lumbar curve in place, the femoral heads move down and medially. There is no way to calculate to what extent individual pelvic rotation will change the CE angle, a configuration derived strictly from the supine x-ray. Yet, it does not matter because orthopedic surgeons are only interested in treating DDH surgically.
After a decade of disastrous results treating dysplasia with arthroscopic surgery to “repair” labral tears4, the standard of care has become the periacetabular osteotomy (PAO). Surgeons believe the goal of treatment “should be the restoration of hip anatomy as close to normal as possible.”5 PAO is the preferred technique “because of its balance between minimal exposure, complications, and ability to provide optimal correction.”6
In reality, orthopedics has an extremely inaccurate view of pelvic orientation, and rather than restoring normal anatomy, PAO changes the pelvis to a configuration that does not occur in nature. Drawn from centuries of misperception, orthopedics believes “Two strong osseous columns of bone surround the acetabulum, transmitting the stresses between the trunk and lower extremities.”7 (Figure 3)
The most current orthopedic literature proclaims that PAO “preserves the posterior column of the acetabulum and therefore allows early weight-bearing post-operatively.”8
Actually, in the standing body the pelvic inlet is in a vertical position, and the so-called bony “columns” are horizontal, not vertical. In 1955 it was recognized that gravitational forces are carried around the linea terminalis (circular pelvic inlet) and distributed onto the femoral heads.9 (Figure 4)
Surgeons contend, “The pelvic ring and outlet are not disrupted by PAO”10, yet anyone who has ever seen a post-PAO x-ray knows the fallaciousness of such statements. Another selling point of the PAO is that, “It can be performed through one incision without violation of the abductors, thus enhancing recovery.”11 The following summary of the steps in the soft-tissue dissection and exposure prior to the actual osteotomy illuminates the devastating and irreversible trauma that accompanies PAO.12
- External oblique incision and exposure of iliac crest.
- Subperiosteal iliacus dissection.
- Detachment of sartorius origin and inguinal ligament attachment through anterior superior iliac spine osteotomy.
- Incise fascia of tensor fascia lata muscle.
- Dissect tensor fascia lata from intermuscular septum.
- Exposure of lateral rectus femoris muscle belly and medial retraction to identify distal hip capsule.
- Release reflected head and direct head of rectus femoris.
- Incise fascia of capsular extension of iliacus muscle and dissect muscle exposing entire anterior hip capsule.
- Subperiosteal dissection of pubic root and entrance into iliopectineal bursa.
- Insert Hohmann retractor into pubis, flex hip, and retract psoas muscle. Overly vigorous traction may injure femoral nerve.
- Complete dissection of anterior hip capsule and interval between psoas tendon sheath and hip capsule.
- Incise periosteum of pubis and perform subperiosteal anterior and posterior pubic dissection reflecting the obturator membrane from the inferior pubis.
- Reflect iliopectineal fascia from iliopectineal line.
- The iliac nutrient artery located anterior to the distal sacroiliac joint should be cauterized and sealed with bone wax.
The next step is the osteotomy itself, whereby the acetabulum is sawn in three places and rotated with the intention of better covering the femoral head by the acetabular roof. The established maneuver in PAO is to turn the acetabular fragment into flexion, lateral tilt, and medial rotation. (Figure 5)
“Every effort should be made to orient the acetabular sourcil in a horizontal position relative to the weight-bearing zone of the femoral head. The anterior and posterior walls of the acetabulum should be positioned so that the posterior wall is lateral to the anterior wall.”13
One of the great medical outrages of the 21st century is that what these surgeons are trying to reproduce is not normal anatomy, but the misconstrued reflection of the 2D pelvic x-ray. In the flesh-and-blood standing pelvis, the posterior wall is medial to the anterior wall, due to the oblique nature of the pelvis from the wide anterior superior iliac spines in front, to the more narrow ischial tuberosities in back. (Figure 6)
It is also a tragic irony that the goal of PAO is to get the “femoral head centered under the acetabular roof”14 when this is the natural biomechanical result of sitting, standing, walking, and running with a wide-radius lumbar curvature.
Reinhold Ganz, the orthopedic surgeon who popularized the PAO, recently reported that a 10-year follow-up revealed one-third of his PAO patients had developed femoroacetabular impingement (FAI) as a result of the operation.15 It is logical to assume this would cause orthopedic surgeons to pause and reconsider the long-term benefits of the surgery. Instead, the prevalence of PAO is increasing exponentially. Only now, FAI surgery is being routinely added as an adjunct to the PAO operation. “[Hips] are routinely examined intraoperatively and a femoral neck plasty is performed to maintain or enhance motion and to prevent post-PAO acetabulofemoral impingement.”16
Another recent source tells us, “The longest follow up of PAO to date shows a survivorship, defined as not yet requiring THR or arthrodesis, of 60% at 20 years.”17 These are terrible odds, yet even post-PAO patients seem to be in denial about the realities of the surgery, often encouraging others to submit to the operation. Online support groups serve as funnels, delivering scores of naive victims into the hands of orthopedic hip surgeons.
The theory of acetabular dysplasia has not been challenged since Gunnar Wiberg published his dissertation on the subject in 1939. No one questions that a rudimentary geometric angle drawn onto a 2D x-ray may have no correlation with the reality of the standing body. Or worse, that the natural depression in the front acetabular rim (Figure 7)
is often mistaken for dysplasia and reduced coverage of the femoral head.18 There is no consensus among orthopedic surgeons whether patients with dysplasia benefit from arthroscopy, and what the exact indications for labral repair should be.19
Too often the progression of surgically managed dysplasia is arthroscopy > PAO > THR. Young age is a major risk factor for revision THR, yet untold numbers of post-PAO patients in their teens and twenties are receiving total hips. Many of these surgeries are being conducted in out-patient settings, for which no public records are required to be kept.
The periacetabular osteotomy should be considered a rescue operation to be utilized in the most severe cases of disease and birth defect. The natural history of mild and moderate hip dysplasia has yet to be defined. Moreover, surgeons know “It does seem possible to live a long and asymptomatic life with mild or moderate hip dysplasia.”20
1 Perry K Trousdale R Sierra R Hip dysplasia in the young adult. The Bone and Joint Journal 95-B(11):21-25 2013
3 Zou Z et al Optimization of the position of the acetabulum in a Ganz periacetabular osteotomy by finite element analysis. Journal of Orthopaedic Research 31: 472-479 2013
4 Jackson T Watson J LaReau J Domb B Periacetabular osteotomy and arthroscopic labral repair after failed hip arthroscopy due to iatrogenic aggravation of hip dysplasia. Knee Surgery, Sports Traumatology, Arthroscopy June 13 2013 [Epub ahead of print]
5 Perry 2013
7 Callaghan J Rosenberg A Rubash H The Adult Hip Lippincott-Raven 1998 p.57
8 Perry 2013
9 Davies JW Man’s assumption of the erect posture, its effect on the position of the pelvis. American Journal of Obstetrics and Gynecology 70(5): 1012-1020 1955
10 Perry 2013
12 Zaltz I How to properly correct and to assess acetabular position: an evidence-based approach. Journal of Pediatric Orthopedics 33(1): S21-S28 2013
15 Albers C et al Impingement adversely affects 10-year survivorship after periacetabular osteotomy for DDH. Clinical Orthopaedics and Related Research 471(5): 1602-1614 2013
17 Perry 2013
18 Vandenbussche E et al Hemispheric cups do not reproduce acetabular rim morphology. Acta Orthopaedica 78(3): 327-332 2007
19 Colvin A Harrast J Harner C Trends in hip arthroscopy. The Journal of Bone and Joint Surgery 94: e23(1-5) 2012
20 Jacobsen S Adult hip dysplasia and osteoarthritis. Acta Orthopaedica 77(324) 2006