Bernese Periacetabular Osteotomy

Introduction

• The Bernese periacetabular osteotomy is a powerful acetabular redirection procedure performed by making a series of connecting cuts to free up the acetabulum without disturbing the posterior column.

• It can be performed without abductor dissection, and it can easily be combined with an anterior arthrotomy for intra-articular surgery. Stable fixation allows early postoperative ambulation.

• It is the most commonly performed acetabular redirectional osteotomy for mature hip dysplasia in North America and much of Europe (Fig. 1A–1D).

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Indications

• Symptomatic congruous acetabular dysplasia in a skeletally mature patient with zero to mild osteoarthrosis

  Examination/Imaging

  Physical Examination

• Range of motion (ROM)

  • Passive ROM—flex and extend hip.

  • Limited range implies arthrosis.

• Anterior impingement test

• Hip flexion, adduction, and internal rotation produces groin pain secondary to anterior acetabular pathology (Fig. 2).

• Positive test implies damage to rim tissues.

Not specific for labral tear.

 

 

 

FIGURE 2

 

• Apprehension test

  • Anterior instability is shown by hip extension, adduction, and external rotation producing discomfort secondary to deficient anterior acetabular coverage (Fig. 3).

  • Positive test suggests anterior instability. Commonly positive in acetabular dysplasia.

• Bicycle test

  • Repetitive cycles, especially against resistance at the foot, will produce pain secondary to abductor fatigue. Abductor musculature is palpated for tenderness (Fig. 4).

  • Positive test suggests abductor overload. Commonly positive in acetabular dysplasia.

     

    FIGURE 3

     

     

     

    FIGURE 4

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• • Plain Radiographs

    • Standing anteroposterior radiograph of the pelvis centered on the femoral heads is standard (Fig. 5A).

      • Femoroacetabular congruity can be assessed, as can be the amount of dysplasia, as measured by the lateral center-edge angle and the tilt of the weight-bearing zone (Tönnis angle). Most symptomatic dysplastic hips have a lateral center-edge angle of less than 15° (lower limit of normal is about 25°). Upper limit of normal for roof angle tilt is about 10°; most symptomatic dysplastic hips have a roof angle tilt of more than 15°.

      • Version of the acetabulum can be roughly assessed by the point at which the anterior and posterior rims meet, with their convergence in a point at the lateral edge of the weight-bearing zone reflecting a normally anteverted acetabulum. Crossing over of the anterior and posterior rims more medially suggests acetabular retroversion.

    • False-profile view, which is a 65° lateral standing view, is a sagittal view of the acetabulum, demonstrating anterior coverage of the femoral head by the acetabulum. The lower limit of the anterior center-edge angle is 20° (Fig. 5B).

    • Von Rosen view (flexion-abduction–internal rotation, taken supine).

      • An optional, functional radiograph to simulate coverage by either acetabular or femoral redirection.

      • Useful if passive hip motion is limited and incongruity or hinging is suspected.

   

   

   

  FIGURE 5 A

   

  Magnetic Resonance Imaging

• Most useful with gadolinium contrast.

• Directly demonstrates both the labrum and the articular cartilage. Useful in assessing labral pathology and character of the acetabular cartilage, which can be very useful in the borderline hip with some arthrosis, since in dysplasia, severe cartilage damage can have occurred at a stage at which the thickness of the cartilage is not yet compromised (Fig. 6).

  Surgical Anatomy

• Detailed knowledge of the soft tissue and bony anatomy encountered during the anterior Smith-Petersen approach to the hip is essential (Fig. 7). The lateral femoral cutaneous nerve crosses the interval between the sartorius and tensor and must be carefully protected as it is carried medially when the supra-acetabular ilium and capsule are exposed.

• The femoral neurovascular structures lie anterior and medial to the psoas tendon and are well protected if the continuity of the psoas tendon is respected and the hip is flexed and adducted during dissection anterior and medial to the hip joint.

• The sciatic nerve exits the pelvis through the greater sciatic notch and courses distal to the sciatic notch posterior and lateral to the hip joint. It is protected both by avoiding dissection within the sciatic notch itself and by maintaining the hip relatively extended and abducted when the portions of the osteotomy are made along the posterior column and across the ischium.

   

   

   

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  Bernese Periacetabular Osteotomy

   

  FIGURE 6

   

  Sartorius muscle

   

  Lateral femoral cutaneous nerve

  Anterior superior iliac spine

  Tensor fascia latae muscle

   

   

  FIGURE 7

   

   

   

  FIGURE 8

  Step 5: Osteotomy Cut 5 (Posterior Ischial Osteotomy)

• The remaining osteotomy involves direct cutting or indirect fracture of the small remaining bridge of ischial bone under the acetabulum (Fig. 15A–15C).

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  A

   

   

   

   

   

  B C

  FIGURE 15

   

   

   

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  P EARLS

• Placement of a Weber bone clamp medial to the hip joint on the superior pubic ramus allows an additional force to be applied during the freeing up of the fragment (Fig. 16).

   

• If the fragment resists freeing up, then each portion of the osteotomy may need to be revisited, first with the fragment extended and everted. Gentle tapping with the angled Ganz chisel inside the pelvis within the ischial osteotomy will often complete the division of the ischial bridges, which are usually the points of last resistance.

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  Bernese Periacetabular Osteotomy

   

  FIGURE 16

• Placement of a Schanz screw from anterior to posterior in the acetabular fragment allows the fragment to be extended to stress this small remaining bridge of bone. Simultaneous placement of a bone spreader in the anterior portion of the iliac osteotomy allows further stressing of the intact bony bridge.

• The fragment is thus extended and everted, and internal torque applied through the Schanz screw usually will fracture the remaining deep bone bridges, completing the periacetabular osteotomy.

  Step 6: Acetabular Fragment Mobilization and Reorientation

  Controversies

  • This final portion of the osteotomy may be completed with varying proportions of deep direct cutting with the angled chisel and indirect fracturing by applying twisting forces to the acetabular fragment.

   

• Since the usual dysplastic acetabulum is insufficient both anteriorly and laterally, rotating the fragment mostly in the anterior direction is appropriate; this

  tends to give some lateral coverage as well. This is

  performed by pulling anteriorly and inferiorly with the Schanz screw to rotate the fragment in place. Slight internal rotation of the fragment as it is rotated anteriorly helps to avoid undesired retroversion (Fig. 17A–17C).

• Provisional fixation of the fragment in a corrected position is achieved with smooth Kirschner wires through the iliac crest into the extra-articular portions of the acetabular fragment; 3/32-inch smooth Kirschner wires are useful (Fig. 17D).

• Imaging is carried out to confirm that the desired horizontalization of the weight-bearing zone of the

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  Bernese Periacetabular Osteotomy

   

  A B

   

   

   

  C D

  FIGURE 17

  acetabulum has been achieved, that retroversion has been avoided, and that lateralization also has been avoided. Shenton’s line should be restored and congruence maintained.

• Passive hip flexion and abduction is checked; 90° of passive hip flexion should be maintained. Direct palpation over the anterior capsule should be carried out as the hip is flexed. If any suggestion of impingement is present, then anterior arthrotomy should be carried out and either reduction and correction considered or osteoplasty of the femoral neck to increase offset considered.

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  A B

  FIGURE 18

  Bernese Periacetabular Osteotomy

   

• Definitive fixation is achieved by multiple long cortical screws drilled through the iliac crest into the extra-articular portions of the acetabular fragment. Three or four 4.5-mm screws are usually sufficient. Supplementation of the fixation with an anterior-to-posterior, so-called home run screw from the anterior inferior spine area into the posterior column above the sciatic notch may be useful (Fig. 18A and 18B).

• Trimming of jagged edges, particularly at the superior ramus level and at the anterior inferior spine level, is useful, with this bone being used to pack into the osteotomy clefts.

  Step 7: Anterior Arthrotomy

• Anterior arthrotomy is carried out in most cases, both to confirm that no unstable labral tear is present and to confirm that no femoroacetabular impingement has been created by the acetabular correction.

• A T-shaped anterior capsulotomy is easy to perform and involves no risk to the blood supply to the femoral head (Fig. 19).

• The labrum is examined and débrided if an unstable tear is present. The hip is carefully flexed, abducted, and internally rotated with the capsule open, and any potential impingement is eliminated, either by reducing the amount of acetabular redirection as mentioned above, or by anterolateral femoral neck osteoplasty, or by a combination.

• The capsule is then loosely closed after hemostasis of any area of bone resection is achieved.

  Step 8: Soft Tissue Repair

• Soft tissue repair routinely is carried out with absorbable suture.

   

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  Bernese Periacetabular Osteotomy

   

  FIGURE 19

   

  • If the rectus has been dissected, it is repaired through a drill hole through bone.

  • The medial iliac periosteum is sutured to the ilium through drill holes.

  • The anterior superior spine osteotomy is anatomically repaired with a 4.0-mm cancellous screw and washer (Fig. 20).

     

     

    3

     

    2

     

    1

     

     

     

    cancellous

    screw

    Anterior superior iliac spine osteotomy repair

     

     

    FIGURE 20

     

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    P EARLS

    • Careful positioning in bed to avoid pressure on the peroneal nerve and other pressure points is essential, especially if postoperative epidural anesthesia is employed.

       

    • Maintaining the hip flexed approximately 30° for the first several postoperative days is useful to avoid pressure from the psoas tendon on the superior ramus osteotomy site.

     

    Bernese Periacetabular Osteotomy

     

    Postoperative Care and Expected Outcomes

• Endotracheal anesthesia with continuous epidural supplementation is routine. Continous epidural anesthesia routinely is employed for 48–72 hours postoperatively, with general ROM active assisted exercises carried out even while in bed. A continuous passive motion machine is employed if extensive intra-articular work has been done.

• Mobilization to a partial weight-bearing gait with two crutches begins on the third postoperative day.

• Antigravity exercises are avoided until good leg control and bony healing are seen, usually at 6–8 weeks following surgery.

• Postoperative anticoagulation is used in adult patients.

• Millis MB, Kim YJ. Rationale of osteotomy and related procedures for hip preservation: a review. Clin Orthop. 2002;405:108–21.

   

  This broad-based review presents the contemporary mechanistic paradigm for the prevention and treatment of osteoarthrosis in the hip by realignment osteotomy. (Level V evidence)

   

  Millis MB, Murphy SB. Periacetabular osteotomy. In Callaghan J, Rosenberg AG, Rubash HE (eds). The Adult Hip. Philadelphia: Lippincott Williams & Wilkins, 2007:795–815.

   

  This is a contemporary complete presentation of the indications for, the use of, and the relevant techniques involved in periacetabular osteotomy. (Level V evidence)

   

  Murphy SB, Millis MB. Periacetabular osteotomy without abductor dissection using direct anterior exposure. Clin Orthop. 1999;364:92–8.

   

  This important study describes the now-standard abductor-sparing approach for periacetabular osteotomy, emphasizing the possibility for the osteotomy to be carried out by the experienced surgeon without disrupting the abductor origin. (Level V evidence)

   

  Murphy SB, Deshmukh R. Periacetabular osteotomy: preoperative radiographic predictors of outcome. Clin Orthop. 2002;405:168–74.

   

  Murphy and Deshmukh document the importance of punctual radiographs in determining likely outcome of periacetabular osteotomy. Hinging detected on functional radiographs predicted high risk of poor outcome. (Level IV evidence)

  Evidence

  Ganz R, Klaue K, Vinh TS, Mast JW. A new periacetabular osteotomy for the treatment of hip dysplasia. Clin Orthop. 1988;232:26–36.

   

  This is the classical original description of Bernese periacetabular osteotomy, including the original series from Berne. (Level IV evidence)

   

  Harris WH. Etiology of osteoarthritis of the hip. Clin Orthop. 1986;213:20–33.

   

  Dr. Harris’ interesting essay elucidates his thesis that nearly all, or perhaps all osteoarthritis of the hip is secondary. He suggests developmental abnormalities and deformities as the commonest etiologic factors in the development of OA in the hip. (Level V evidence)

   

  Kim YJ, Jaramillo D, Millis MB, Gray M, Burstein D. Assessment of early osteoarthritis in hip dysplasia with delayed gadolinium-enhanced magnetic resonance imaging of cartilage. J Bone Joint Surg Am. 2003;85A:1987–92.

   

  Kim et al present an innovative and potentially extremely useful non-invasive imaging technique for assessing the functional integrity of articular cartilage in the mature dysplastic hip. This so-called dGEMRIC technique correlated much better with symptoms than either plain radiographic measures or more standard MR. (Level III evidence)

   

  Leunig M, Siebenrock KA, Ganz R. Rationale of periacetabular osteotomy and background work. Instr Course Lect. 2001;50:229–38.

   

  This is an in-depth analysis of the mechanical and clinical rationale for periacetabular osteotomy, presented in clear fashion by the originator of the technique and coworkers. (Level V evidence)

   

  Millis MB, Murphy SB. [The Boston concept. Peri-acetabular osteotomy with simultaneous arthrotomy via direct anterior approach]. Orthopade. 1998;27:751–8.

   

  This series of periacetabular osteotomies carried out with simultaneous anterior arthrotomy documents the relatively high frequency of labral tears in symptomatic dysplastic hips treated by periacetabular osteotomy, ranging from more than 20% in hips treated during the third decade to more than 40% in hips treated during the fifth decade of life. (Level IV evidence)

   

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  Millis MB. Reconstructive osteotomies of the pelvis for the correction of acetabular dysplasia. In Sledge CB (ed). Master Techniques in Orthopaedic Surgery. New York: Lippincott-Raven, 1998:157–82.

   

  This well-illustrated chapter outlines well both indications and techniques of rotational acetabular osteotomy and Bernese periacetabular osteotomy. The descriptions are somewhat dated in that the emphasis is given to the classic Smith-Petersen exposure of both inner and outer wall of the pelvic, rather than the more contemporary abductor-sparing exposures. (Level V evidence)