Pelvic Osteotomies — A Comparative Overview

Why operate on the pelvis in dysplasia. In developmental dysplasia of the hip (DDH) and residual acetabular dysplasia, the acetabulum provides deficient anterolateral cover of the femoral head. This concentrates load over a small contact area, produces high cartilage contact stress, and drives premature osteoarthritis. Pelvic osteotomies aim to either reorient or reshape the native socket (reconstructive intent) or, where this is not possible, increase the weight-bearing area with a buttress (salvage intent). The three families. Every pelvic osteotomy belongs to one of three families, and naming the family is the first thing an examiner wants to hear:

Examiner framework for choosing. "I assess three things in order — is the triradiate OPEN or CLOSED, is the joint CONGRUENT or INCONGRUENT, and what is the patient AGE and the magnitude of correction required. If the joint is incongruent and cannot be reduced, I move to a salvage procedure regardless of age. If congruent, I choose redirectional or reshaping based on triradiate status and the correction needed." Step 1 — Is the joint congruent and reducible? If no (incongruent, irreducible), choose SALVAGE (Chiari or shelf/Staheli). If yes, proceed to reconstructive options. Step 2 — Is the triradiate open or closed? Open and skeletally immature: a young child with limited correction and a mobile symphysis favours Salter; a need to reduce acetabular volume or reshape the roof favours Pemberton or Dega. Closing or recently closed, with more correction needed in an older child, favours the triple innominate. Closed (adolescent or adult) with a congruent spherical joint favours the periacetabular osteotomy (PAO). Step 3 — Is there coexisting femoral deformity? Excessive anteversion, coxa valga, or a high dislocation means adding a proximal femoral osteotomy (varus derotation osteotomy, VDRO, with or without shortening) to the pelvic procedure.

Combination with femoral osteotomy. Pelvic osteotomies are frequently combined with a proximal femoral osteotomy when there is coexisting femoral deformity — excessive anteversion, coxa valga, or to improve concentric reduction and head-neck offset. The pelvic side corrects acetabular deficiency; the femoral side corrects proximal femoral morphology. In high dislocations a femoral shortening osteotomy may be added to reduce the head safely and lower the risk of avascular necrosis. Setup. Most pelvic osteotomies share a supine position and an anterior approach (Smith-Petersen, modified ilioinguinal, or a bikini incision for the PAO). The lateral femoral cutaneous nerve near the anterior superior iliac spine is identified and protected at the outset, and intra-operative fluoroscopy is used throughout to confirm every cut, the fragment reorientation, and that no cut has entered the joint.

This is a comparative overview, so the operative detail below centres on the periacetabular osteotomy (PAO; Ganz/Bernese) — the modern, most technically demanding and most frequently examined operation, and the one performed for the adolescent or adult with a closed triradiate and a congruent dysplastic hip. The exposure is laid out in full as the first steps: it is the heart of the operation. The mechanisms of the other osteotomies (Salter, triple, Pemberton, Dega, Chiari, shelf) are detailed in the comparison tables under Background & Evidence.

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The other two families are illustrated below — the redirectional osteotomies (Salter, triple, PAO) reorient a congruent socket, while the salvage osteotomies (Chiari, shelf) create fibrocartilaginous cover for an incongruent one. Their mechanisms are compared in the tables under Background & Evidence.

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Immobilisation and weight-bearing vary by operation. Young children typically need a hip spica after Salter, Pemberton and Dega osteotomies. The triple innominate also needs protected weight-bearing. The PAO, by contrast, permits early protected weight-bearing because the posterior column and pelvic ring are preserved. Fixation differs accordingly: Salter uses K-wires with an interposition bone graft; the triple uses screws or wires; the PAO uses multiple screws into the fragment; Pemberton and Dega are held by graft wedges, often without internal fixation in young children, supplemented by a spica. Complications. Pelvic osteotomies sit close to the sciatic, femoral, obturator and lateral femoral cutaneous nerves, to the joint itself, and to the blood supply of the acetabulum and femoral head. Recognition, prevention and management of the important complications are summarised below.

Critical decision points and exam traps. These are the distinctions examiners use to separate a candidate who has merely memorised the names from one who understands when each operation applies.

Pathoanatomy — why the dysplastic hip degenerates. The deficient anterolateral cover of the dysplastic acetabulum concentrates the joint reaction force over a small contact area. The resulting high cartilage contact stress drives labral failure and progressive cartilage wear, culminating in premature osteoarthritis. The reconstructive osteotomies work by restoring a larger, well-oriented hyaline-cartilage weight-bearing surface; the salvage osteotomies accept that this is impossible and instead enlarge the weight-bearing area with fibrocartilage. The redirectional family — mechanism. The acetabulum is of essentially normal shape but malpositioned. The osteotomy reorients the entire intact socket over the head. - Salter (single innominate): one supra-acetabular iliac cut, hinging on the symphysis pubis; the distal fragment is rotated anterolaterally and downward and held with a bone-graft wedge and K-wires. The symphysis must be mobile (young child). Correction is limited (roughly 15-25 degrees) and it does not change acetabular volume. It can slightly lengthen the limb.

• Triple innominate (Steel / Tönnis): three cuts — ilium, superior pubic ramus and ischium — completely free the acetabular fragment, which can be redirected more freely than the symphysis-tethered Salter. The Tönnis (juxta-articular) modification places cuts closer to the acetabulum for greater correction with less displacement and better medialisation. The freed fragment is less inherently stable and the posterior column is divided (unlike the PAO).
• Periacetabular osteotomy (PAO; Ganz / Bernese): a series of controlled juxta-articular cuts free the acetabulum as a single fragment while preserving the posterior column, allowing multiplanar correction, stable fixation, early weight-bearing, preserved vascularity and an undistorted true pelvis. It requires a closed triradiate and a congruent, spherical, well-preserved joint.

The reshaping family — mechanism (open triradiate hinge). These bend the acetabulum around the triradiate cartilage, which acts as the hinge, so an open triradiate is mandatory. They reduce acetabular volume and increase cover by changing socket shape. - Pemberton (pericapsular): a curved supra-acetabular cut carried down to the triradiate, which acts as the hinge; levering the roof down and laterally rotates it over the head, reducing volume. It can create incongruity or stiffness if the head is large or the joint is not truly congruent.

• Dega (transiliac / incomplete): an incomplete transiliac osteotomy leaving the posterior (and often medial) iliac cortex intact as a hinge; bone-graft wedges control the direction of correction. The direction of correction is adjustable (anterior, lateral or posterior cover), making it versatile for global or posterior deficiency such as neuromuscular dysplasia. The salvage family — mechanism (fibrocartilage cover for the incongruent hip). Used when the joint is incongruent and cannot be made congruent. They do not reorient hyaline cartilage; they increase the load-bearing surface, which undergoes fibrocartilage metaplasia. - Chiari medial displacement: a curved osteotomy of the ilium just above the acetabular margin; the distal fragment (with the acetabulum) is displaced medially so the overhanging iliac wing becomes a buttress. It medialises the hip centre (reducing the lever arm and joint reaction force). Risks: over-medialisation narrowing the pelvis, sciatic nerve injury, joint penetration.
• Shelf / Staheli (slotted acetabular augmentation): an extra-articular bony shelf slotted into the ilium just above the acetabular rim, extending the lateral roof over the capsule. It does not medialise the hip and relies on a good capsule; the main concern is graft resorption or fracture.

Key evidence. Ganz's original 1988 description established the defining principle of the PAO — powerful multiplanar reorientation through a preserved, vascularised posterior column that allows stable two-screw fixation and early weight-bearing without distorting the true pelvis. The 20-year follow-up of that first cohort (Steppacher, 2008) showed 60 percent of hips preserved free of arthroplasty, with pre-existing arthritis, incongruity, impingement and older age predicting failure — the basis for restricting the PAO to congruent, low-arthritis joints. The 30-year synthesis (Lerch, 2016) reported 10-year survivorship of 80 to 90 percent with optimal reorientation and a spherical head, declining with time, and confirmed the PAO as the standard surgical treatment of symptomatic dysplasia in adolescents and adults. In children, Wang's long-term study showed Pemberton (reshaping) adds more anterior cover than Salter (redirectional), with a measurable impingement risk — validating the mechanistic distinction that drives selection.

References 1. Salter RB (1961). Innominate osteotomy in the treatment of congenital dislocation and subluxation of the hip. J Bone Joint Surg Br. — Original description of the single innominate osteotomy hinging on the symphysis pubis. 2. Steel HH (1973). Triple osteotomy of the innominate bone. J Bone Joint Surg Am. — Description of the triple innominate osteotomy for greater acetabular redirection. 3. Ganz R, Klaue K, Vinh TS, Mast JW (1988). A new periacetabular osteotomy for the treatment of hip dysplasias: technique and preliminary results. Clin Orthop Relat Res. (232):26-36. PMID 3383491. — Original description of the Bernese (Ganz) periacetabular osteotomy, including preservation of the posterior column. 4. Steppacher SD, Tannast M, Ganz R, Siebenrock KA (2008). Mean 20-year followup of Bernese periacetabular osteotomy. Clin Orthop Relat Res. 466(7):1633-44. PMID 18449617. — 60 percent hip preservation at 20 years; predictors of poor outcome. 5. Thawrani D, Sucato DJ, Podeszwa DA, DeLaRocha A (2010). Complications associated with the Bernese periacetabular osteotomy for hip dysplasia in adolescents. J Bone Joint Surg Am. 92(8):1707-14. PMID 20660233. — Major and minor complication profile in adolescents. 6. Wang CW, Wu KW, Wang TM, Huang SC, Kuo KN (2013). Comparison of acetabular anterior coverage after Salter osteotomy and Pemberton acetabuloplasty: a long-term followup. Clin Orthop Relat Res. 472(3):1001-9. PMID 24096458. — Pemberton (reshaping) adds more anterior cover than Salter (redirectional). 7. Lerch TD, Steppacher SD, Liechti EF, Siebenrock KA, Tannast M (2016). Bernese periacetabular osteotomy: indications, technique and results 30 years after the first description. Orthopade. 45(8):687-94. PMID 27250618. — 30-year survivorship synthesis. 8. Pemberton PA (1965). Pericapsular osteotomy of the ilium for treatment of congenital subluxation and dislocation of the hip. J Bone Joint Surg Am. — Original description of the pericapsular (Pemberton) osteotomy hinging on the triradiate cartilage. 9. Chiari K (1974). Medial displacement osteotomy of the pelvis. Clin Orthop Relat Res. — Description of the Chiari medial displacement salvage osteotomy. 10. Staheli LT (1981). Slotted acetabular augmentation. J Pediatr Orthop. — Description of the slotted (Staheli) shelf acetabular augmentation salvage technique. 11. Tönnis D, Behrens K, Tscharani F (1981). A modified technique of the triple pelvic osteotomy: early results. J Pediatr Orthop. — Juxta-articular modification of the triple osteotomy allowing greater correction.