1. PELVIC OSTEOTOMY FOR THE TREATMENT OF THE YOUNG ADULT WITH HIP PAIN Emmanuel Illical, Adult Reconstruction Fellow

2. OUTLINE Pelvic osteotomy introduction Background: hip dysplasia
Bernese periacetabular osteotomy (PAO)
Technique & Surgical adjuncts
Advantages & Complications
Clinical Results
Background: acetabular retrotorsion
Reverse PAO
Principles
Other osteotomies
Salvage Osteotomies
Summary

3. PELVIC OSTEOTOMY: INTRODUCTION
Treatment of choice for acetabular structural disorders for young pts
classical developmental hip dysplasia
retrotorsional acetabular abnormalities
Indications
symptomatic patient (pain / progressive limp)
radiographically negative for advanced OA
adequate and relatively painless passive ROM
Rationale
restore normal hip anatomy and biomechanics
increase joint congruity
optimize center of rotation
relieve symptoms
prevent (possibly delay?) degenerative changes
Challenges: diagnosis & predictability of outcome •

4. BACKGROUND: HIP DYSPLASIA
Acetabular abnormalities
shallow
anteverted (retrortosion in up to 25%)
lateralized
femoral head coverage deficient anteriorly, laterally, superiorly
Femoral abnormalities
proximal migration
femoral head small and deformed
femoral neck short and narrrow w/ varying but but  anteversion
valgus neck shaft angle
femoral canal narrow
Secondary degenerative joint disease over time
 contact area btwn femoral head and acetabulum
excessive lateralization of body weight lever arm   body weight lever arm
relatively high forces transmitted through  surface area

5. BACKGROUND: HIP DYSPLASIA
Acetabular coverage
- extrusion index > 20%
- lateral CEA (of Wiberg) <20*
- acetabular index / Tonnis angle >10*
- acetabular angle (of Sharp) >47*
- acetabular retroversion up to 25% of cases
Joint congruency
- Crowe classification
- Shenton line integrity measures subluxation of femoral head in vertical direction
often interrupted
- lateralization of femoral head measures subluxation of femoral head in horizontal direction
shortest distance btwn medial aspect of femoral head and ilioischial line  dysplasia > 16 mm

6. BACKGROUND: HIP DYSPLASIA
Anterior centre edge angle via FALSE PROFILE
- subject stands at an angle of 65* oblique to xray beam w/ foot on affted side parallel to beam (focal distance 1 m)
- horizontal centre = tip of GT; vertical centre = midway btwn symphysis pubis and ASIS
- represents true lateral of acetabulum  assesses degree of femoral anterior coverage
- vertical line through centre of femoral head + line extending from centre of femoral head to anterior sourcil
- normal = 25-50; dysplasia <25*
to assess anterior femoral head neck junction:
axial cross table lateral (contralateral hip flexed; xray beam at 45 to affected hip)
Dunn view (45/90 flexion; 20 ABduction; neutral rotation)
ANTERIOR sphericity
alpha angle
objective representation of the prominence of the anterior femoral head neck junction (CAM type)
normal < 50; CAM > 50
line perpendicular to femoral neck at narrowest point (a); second line perpendicular to (a) i.e. parallel to neck (b)
benefit circle drawn outlining femoral head
angle = line b  line to point of where femoral head protrudes anterior to circle
offset
distance from femoral neck  line perpendicular to superior femoral head outline
normal > 10 mm; CAM < 10 mm
offset ratio
ratio btwn anterior offset and femoral head diameter
normal /- 0.03; CAM < 0.18

7. BERNESE PAO: TECHNIQUE
• indications for dysplasia
- symptomatic
- no excessive proximal migration of hip center of rotation
- no more than mild to moderate articular degenerative changes (Tonnis grade < 2)
- reasonable joint congruity (if no congruency on AP pelvis then do AP pelvis xray with hip in ABduction and IR  if concentrically reduced now then needs femoral VDRO)
• current technique  abductor sparing modification of anterior (Smith-Peterson) approach
• four osteotomies from inner pelvis:
- infra-acetabular ischial osteotomy: anterior ischium just distal to lip of acetabulum, aims toward midline of ischial spine
- superior pubic ramus osteotomy
- supra-acetabular iliac osteotomy: just proximal to ASIS toward sciatic notch
- posterior column osteotomy: bisecting between articular surface anteriorly and posterior cortex
• Shanz pin then placed into acetabular fragment in supra-acetabular region  mobility tested
• large universal red’n clamp placed around iliac portion of acetabular fragment & Schanz pin  acetabcular fragment mobilized
• acetabulum repositioned to optimize surgical correction = MOST IMPORTANT STEP
1) internal rotation (lateral coverage and anteversion)
2) forward tilt or extension (anterior coverage)
3) medial translation (medialization of joint center)
(finally, superior translation to achieve bone to bone contact w/ overlying ilium & minimizes lengthening of exremity w/ extensive corrections)
• acceptable correction:
- Shenton’s line near normal
- roof horizontal (Tonnis angle < 10*)
- femoral head congruent (ideally lateral extrusion index < 20%)
- femoral head medialized (to within 5-15 mm of ilioischial line)
- anterior rim covers less of femoral head than of posterior rim (assuring proper anteversion)
- ideally: anterior wall to cover 1/3 of femoral head, posterior wall to cover 1/2 of femoral head, both walls should met at lateral aspect of sourcil
- retroversion = posterior wall meets sourcil medial to anterior wall
• important that acetabulum NOT be over-reduced or retroverted
- causes problematic impingement (mostly anterior but possibly lateral)
- slight undercorrection is preferred to excessive correction
- identify anterior and posterior walls intra-operatively to assess degree of version
- best avoided using an inward rotation maneuver (around an AP axis) and avoiding excessive extension of the acetabular fragment
• acetabular fragment fixed with two or three long 4.5 cortical screws

8. BERNESE PAO: SURGICAL ADJUNCTS
Anterior arthrotomy: before or after PAO
labral pathology: debridement / repair
femoral head neck junction: osteochondroplasty
Proximal femoral osteotomy
severe coxa valga / vara  varus / valgus producing intertrochanteric osteotomy

9. BERNESE PAO: ADVANTAGES
Only one incision that spares ABductors
Reproducible extra-articular osteotomies
Allows large corrections in all directions
Posterior column remains intact
minimal internal fixation required
early mobilization w/o external immobilization
Preservation of acetabular fragment vascularity
intra-articular examinzation w/o further risk of devascularization
True pelvis shape is unchanged
child bearing & vaginal delivery not affected

10. BERNESE PAO: COMPLICATIONS
Most important factor affecting incidence = surgeon experience
Most common complication = nerve dysfunction
lateral femoral cutaneous nerve (35%)
femoral nerve
sciatic / peroneal nerve
Vascular
related ilioinguinal approach: femoral / iliac artery thrombosis
Inadvertent extension of osteotomy to undesirable location
intra-articular extension of infra / supra – acetabular osteotomies
sciatic notch extension of iliac osteotomies
Femoroacetabular impingement
Osteonecrosis of acetabular fragment
Nonunion
Other: HO, loss of correction, femoral head subluxation
• nerve dysfunction
- LCFN = up to 35%; normally do not require further treatment
- femoral = usually with less commonly direct anterior approach or pts with previous surgeries
- sciatic = most at risk with infra-acetabular osteotomy & posterior column osteotomy
• vascular complication  Hussell JH, Rodriquez JA, Ganz R. Techincal complications of the Bernese PAO. Clin Orthop :81-92.
• inadvertent extension of osteomies
- intra-articular extension of infra-acetabular ischial osteotomy:
- reported in hips with marked proximal femoral head migration + lax or empty inferior capsule
- difficult for surgeon to be positioned distal enough from anterior aspect of hip to perform osteotomy
- DOES NOT cause articular congruence BUT can interrupt blood supply  contributes to osteonecrosis of acetabular fragment
- intra-articular extension of supra-acetabular iliac osteotomy (vertical limb)
- DOES create incongruent joint after correction  arthrosis
- sciatic notch extension
- goes through posterior column  destabilizes pelvic ring
• FAI - over correction of osteotomized fragment can lead to anterior or lateral impingement sxs OR posterior subluxation of femoral head
- failure to recognize or address lack of femoral head neck offset at time of PAO via anterior arthrotomy
• ON - extensive stripping of external iliac fossa
- interruption of blood supply by osteotomies
- previous surgery
• nonunion - pubic osteotomy > ischial osteotomy > iliac osteotomy
- may be due to large interfragmentary gaps
- most pubic nonunions asymptomatic  bone grafting at time of surgery does not seem to effectively reduce incidence
- bone grafting / plate fixation of ischial / iliac nonunions rarely needed
• HO - significantly decreased with use of modified Smith-Pete approach; usually asymptomatic
• loss of correction - insufficient fixation / early weight bearing
• femoral head subluxation - 2* impingement or neglecting associated femoral deformity

11. BERNESE PAO: CLINICAL RESULTS
Clohisy et al. - contraindications to PAO are functional radiographs showing:
- impingement (due to lack of femoral head red’n),
- levering out of femoral head (lack of concentricity)
- localized jt space narrowing (incongruity)
- adequate ROM that will tolerate major re-orientation of acetabulum: 105* flexion, 30* ABduction
- minimal or no secondary arthritis (mod to advanced disease compromises result)
- false acetabulum = less predictable result
Kralj et al. - long term success depends on grade of preop arthosis & magnitude of operative correction
Siebenrock et al - factors associated with unfavourable outcome
- older age at time of procedure
- moderate to severe pre-op arthrosis
- associated labral lesion
- less anterior coverage correction
- suboptimal post-op acetabular index
Take away message - successful operation with no more than moderate degenerative changes (Tonnis 0-2)
- most difficult part of procedure is determining amount of correction needed in each case

12. BERNESE PAO: CLINICAL RESULTS
Bekke et al, 2011
- presence of two consultants at initial series of operations helped with overcoming difficulties with orientation and osteotomy positions
Ito et al 2011
- PAO for pts > 40 remains important option for older pts not willing to undergo THA given selection criteria
- good preop joint congruency
- short stature, low BMI
- HHS actually decreased slightly from 5 yr f/u to latest f/u  more so for pts > 40
- clinical results may deteriorate after 5 years
Matheney et al (Boston group)
- failure was defined was need for THA or WOMAC > 10
- 15% complication rate:
- 9(6.7%) transient peroneal nerve palsy
- 6(4.4%) wound hematoma requiring drainage
- 2 asymptomatic nonunion of sup pubic ramus
- 2 brooker 3 HO
- 1 intrapelvic abscess 2 months post op
- two independent predictors of failure (14% no predictors, 36% 1 predictor, 95% both predictors)
- age > 35
- poor or fair preop joint congruency (Yasunaga et al J Bone Joint Surg Am. 2006;88: )
- excellent = radii of curvature of acetabulum and femoral head almost identical; joint spaced maintained
- good = radii of curvature not identical but joint space maintained
- fair = radii of curvature not identical and partial narrowing of joint space
- poor = partial disappearance of joint space
Steppacher et al (Bern group) identified 6 factors predicting poor outcome
- increased age at surgery HR 1.08 (per year older)
- pre-op d’Aubigne score HR 1.31 (per point lower)
- +ve ant impingement test HR 6.17
- limp HR 2.87
- OA grade HR 3.39 (per grade higher)
- post-op extrusion index HR 1.11 (per % less)

13. BACKGROUND: ACETABULAR RETROTORSION
Posteriorly oriented acetabular opening (sagittal plane)
Etiology
isolated entity
associated w/ classic hip dysplasia
injury to tri-radiate cartilage in growing child
associated with LCP, bladder extrophy, neuromuscular d/o
Typical presentation is groin pain reproduced with “impingement signs”
Recurrent impingement has been implicated in development of 2* arthrosis
• impingement signs: flexion + ADduction + IR

14. BACKGROUND: ACETABULAR RETROTORSION
• crucial to determine acetabular version on standardized AP pelvis
• anteversion = anterior wall should cover less of femoral head than posterior wall + contours of ant and post wall edges usually meet superior and lateral (lateral edge of sourcil)
• normally visible outline of posterior wall on AP should ie at CENTER of femoral head
SIGNS INDICATIVE OF ACETABULAR RETROVERSION
• cross over sign
- ant and post wall edges meet distal to normal superolateral meeting point (i.e. posterior wall meets sourcial medial to anterior wall)
- anterior wall directed more horizontally and medially  thereby “crossing over” the more straight and vertical posterior wall
• ischial spine sign
- projection of ischial spine into pelvic cavity
- Kalberer et al (CORR 2008)  91% sensitivity, 98% specificity, 98% PPV, 92% NPV
• posterior wall sign
- posterior wall outline passes medial to center of femoral head
- indicates relatively less posterior femoral head coverage
• posterior aspect of acetabulum subject to high loads during ADLs
- greater loads imposed on posterior cartilage  degenerative changes
- “contrecoup lesion”: femoral head subluxates posterioly when femoral head neck region impinges with prominent anterior acetabular rim

15. REVERSE PAO: PRINCIPLES
Treatment of choice when acetabular retrotorsion exists
+ve crossover sign AND +ve posterior wall sign (poor posterior coverage)
addresses lack of posterior wall coverage by increasing anteversion
Technique
same approach and osteotomies as PAO
re-orientation achieved by combined flexion + IR of acetabular fragment
goals: eliminate xray signs+ sufficient impingement free ROM (flexion + IR)
posterior over-coverage is a concern
arthrotomy / SHD to address femoral head neck offset & labral pathology
Contra-indications
excessive posterior wall coverage / AI < 0*  impingement
significant combined CAM / pincer deformity  requires surgical hip dislocation
advanced cartilage degeneration  area would end up in weight bearing zone
• posterior over-coverage  posterior acetabular impingment in extension + ER
• excessive posterior wall coverage = “deep” hips (coxa profunda / protrusio) -

16. REVERSE PAO: CLINICAL RESULTS
Siebenrock et al. JBJS Am Impingement due to acetabular retroversion. Treatment with PAO.
29 reverse PAOs to reorient retroverted acetabulum (+ve cross over / pw sign)
concominant femoral head neck osteochondroplasty in 24 hips
avg 30 month f/u
significant increase in flexion / IR / ADduction
significant d’Aubigne hip score improvement: 14.0  16.9
28 “good / excellent” results
no pt had radiographic signs of OA
3 revisions
Buchler et al. JBJS Br Symptomatic acetabular retroversion: mean 10 year fu after treatment with PAO.
mean f/u 10.6 year
overall d’Aubinge score improved: 14.0  16.3
all patients had symptomatic relief at final f/u
ROM and functional scores improved in all cases
vast majority of pts continued to demonstrate no signs of radiographic OA
• Siebenrock et al 20003
- three revisions
1) partial loss of correction (screw bending noticed at 8 weeks) requiring second PAO
2) posteriorinferior impingement requiring SHD and posterior rim trimming
3) recurrent signs of anterior impingement  incomplete acetabular correction (persistent cross over sign, poor correction of ant CEA) + decr HN offset
- surgical revision to improve ant femoral head neck offset
- good / excellent = pain absent / markedly decreased
Acetabular retroversion does not have a uniform morphology
degree of overlap of anterior aspect of rim varies considerably
measurements of version at midpart of joint unlikely to describe version in roof area = crucial site for impingement and labral / cartilage lesions -

17. OTHER OSTEOTOMIES
Salter’s single innominate - provides lateral and anterior coverage at the expense of posterior coverage
- insufficient in adults  limited correction due to stiffness of symphysis; lateralizes hip joint
Double / triple osteotomies - devised in part to allow greater acetabular correction and avoid lateralization
- improvement in coverage is limited by size of fragments and liagmentous / muscular attachments to sacrum
- can also lead to marked pelvic deformity if significant correction obtained
- violate posterior column  may require special efforts for stabilization post-op
- mixed results in literature
Spherical osteotomies - Eppright, Wagner, Ninomiya and Tagawa
- provide good lateral coverage
- amount of anterior coverage and ability to medialize hip limited
- partially intra-articular  risk of osteonecrosis
- difficult to reprorduce

18. SALVAGE OSTEOTOMIES
• indications - severely dysplastic hip that cannot be rendered congruent by a reconstructive osteotomy
- i.e. significant discrepancy btwn sizes and shapes of femoral head and acetabulum (obtain AP pelvis with ABduction + IR of femur to assess congruency)
• Chiari iliac osteotomy
- medial displacement osteotomy
- level of AIIS  sciatic notch
- distal fragment displaced medially until femoral head covered
- angled proximally (iliac buttress will be too horizontal + hip may subluxate laterally)
- additional ant buttressing w/ structural bone graft from iliac wing often required to provide anterior coverage (avoid persistant ant instability)
- weight bearing coverage increased by using joint capsule as interposition btwn femoral head and bone above it
- relies on fibrocartilaginous metaplasia of interposed joint capsule to provide an increased articulating surface
- reduces point loading at edge of acetabulum
- contra-indications (poor outcome): older age, advance degenerative changes
- Kotz et al. CORR Long term experience with Chiari’s Osteotomy.
- 80 osteotomies w/ mean f/u 32 years
- 40% undergone THA after average 26 years
- 60% not replaced  median HHS 82
- age at time of surgery inversley correlated with interval btwn osteotomy and THA
- Windhager et al. JBJS Br Chiari osteotomy for congential dislocation and subluxation of hip. Results after years fu
- 236 osteotomies
- 8.9% needed revision .after mean 15.4 years
- 91.1% followed up at mean 24.8 years
- outcome: good 51.$%, fair 29.8%, poor 18.3%
- degenerative changes increased significantly during LT f/u
- outcome worse with: increasing age at operation, pre-op signs of OA
- Lack et al. JBJS Br Chiari pelvic osteotomy for OA 2* to hip dysplasia. Indicaitons and LTF.
- 82 osteotomies > 30 y/o at time of operation. Avg f/u 15.5 years
- 24% undergone THA.
- outcome: good 75%, fair 9%, poor 16%
- outcome worse for patients > 44
- facilitates acetabular cup implantation
Shelf procedures
- corticocancellous bone graft to augment anterolateral part of acetabulum  buttress to increase joint stability
- does not change relationship of femoral head and true acetabulum -- > lacks medialization of hip COR
- published results conflicting
- Fawzy et al. JBJS Br Is there a place for shelf acetabuloplasty in mngt of adult acetbaular dyplasia?
- 76 hips; mean f/u 11 years
- survival analysis (conversion to THA):
- overall: 86% at 5 years; 46% at 10 years
- no / slight joint space narrowing: 97% at 5 years; 75% at 10 years
- moderate or severe joint space narrowing: 76% at 5 years; 22% at 10 years
- Summers et al. Shelf operation in mgnt of late presentation CHD.
- 27 hips; mean age 14 years at time of operation; mean f/u 16 years
- highest likelihood of success = pts < 20 with little/no radiographic OA -

19. SUMMARY Full pre-operative work-up Select patients appropriately
assess degree of dysplasia and acetabular version
assess femoral head neck offset
assess labral pathology
Select patients appropriately
symptomatic
be aware of age
no more than mild to moderate articular degenerative changes (Tonnis grade < 2)
reasonable joint congruity (obtain functional xrays if necessary)
Surgeon experience key to minimizing complications