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In adolescents and young adults with severe dysplasia who require an acetabular rotation of more than 20 degrees, the traditional recon-structive approaches include the double innominate

Osteoarthritis of the hip is a

com-mon disease in the United States,

affecting at least 1 million persons

under age 50.1 Total hip arthroplasty

is not an ideal treatment for young

adults with osteoarthritis, because

of problems with component

loos-ening and premature wear

Many young patients in whom

osteoarthritis of the hip will

ulti-mately develop have an underlying

mechanical abnormality of either

the acetabulum or the proximal

femur (hip dysplasia) Early hip

os-teoarthritis frequently involves

concentrated stress on the cartilage

in a small portion of the hip-joint

circumference, typically the lateral

acetabular margin Rotational

pelvic osteotomies distribute and

decrease stress by enlarging the

weight-bearing cartilage area of the

acetabulum Adults and

adoles-cents with a hip center-edge angle

of less than 16 degrees are at high

risk for osteoarthritis, especially

when hip subluxation is present.2-4 Reconstructive hip joint osteoto-mies may forestall the onset of osteoarthritis in patients with dys-plastic hips and allow the postop-erative return to high-impact work and sports

In adolescents and young adults with severe dysplasia who require

an acetabular rotation of more than

20 degrees, the traditional recon-structive approaches include the double innominate osteotomy,5 the triple innominate osteotomy,6-13 the Bernese periacetabular

osteoto-my,14,15and the spherical acetabular osteotomy.16-20 Pelvic osteotomies are technically difficult and usually require an extensive hip exposure, which can result in prolonged post-operative hip weakness An endo-scopic method of performing triple innominate osteotomy has been developed in an effort to decrease the invasiveness of rotational pelvic osteotomy Early clinical results

suggest that this endoscopic ap-proach provides excellent acetabular rotation and femoral head coverage with reduced surgical morbidity

Technique for Endoscopic Pelvic Osteotomy

The preoperative evaluation should include the following pelvic radio-graphs: anteroposterior (AP)

weight-Dr Wall is Director of Sports Medicine, Division of Orthopaedic Surgery, Children’s Hospital Medical Center, Cincinnati, Ohio.

Dr Kolata is Research Fellow, Ethicon Endo-Surgery, Cincinnati Dr Roy is Associate Director of Pediatric Orthopaedic Surgery and Director of the Hip Service, Children’s Hospital Medical Center Dr Mehlman is Director of Musculoskeletal Outcomes Research, Chil-dren’s Hospital Medical Center Dr Crawford

is Director of Pediatric Orthopaedic Surgery, Children’s Hospital Medical Center.

One or more of the authors or the departments with which they are affiliated have received something of value from a commercial or other party related directly or indirectly to the sub-ject of this article.

Reprint requests: Dr Wall, Department of Orthopaedic Surgery, Children’s Hospital Medical Center, 3333 Burnett Avenue, Cincinnati, OH 45229.

Copyright 2001 by the American Academy of Orthopaedic Surgeons.

Abstract

Adolescent and adult hip dysplasia can be surgically treated by rotating the

acetabulum into a better weight-supporting position; however, open pelvic

osteotomies are among the most invasive of all pediatric orthopaedic procedures.

Endoscopic pelvic osteotomy offers the theoretical advantages of magnified

visu-alization of the bone cuts, minimized surgical dissection, and rapid

postopera-tive recovery The technique of endoscopically assisted triple innominate

osteotomy requires the combination of endoscopic skills and facility with more

standard surgical approaches.

J Am Acad Orthop Surg 2001;9:150-156

Endoscopic Pelvic Osteotomy for the Treatment of Hip Dysplasia

Eric J Wall, MD, Ron Kolata, DVM, Dennis R Roy, MD, Charles T Mehlman, DO, MPH, and Alvin H Crawford, MD

bearing, AP supine, AP supine with

maximal hip abduction and internal

rotation, and frog-leg lateral views,

as well as a false-profile view of the

hip A computed tomographic study

of the entire pelvis with

three-dimen-sional reconstructions should also be

obtained to help plan the degree and

direction of rotation The patient

should have near-normal hip range

of motion preoperatively and

radio-graphic evidence of concentric hip

reduction with the lower extremity

in abduction For patients with

me-chanical symptoms, such as locking,

painful clicking, and catching, a

mag-netic resonance imaging study may

be necessary to rule out a labral tear

or an acetabular rim fracture, which

cannot be repaired endoscopically

The patient is placed supine with

the operating room table reversed,

so that the pelvis can be

fluoroscop-ically imaged and the surgeon can

easily view the endoscopy and

fluo-roscopy monitors (Fig 1)

Alter-natively, the patient may be placed

on a modular imaging table Intra-operative blood pressure is lowered

to keep the systolic pressure less than 90 mm Hg A prophylactic antibiotic is administered preopera-tively No neuromuscular paralysis agent is used after intubation

The lower extremity to be oper-ated on is placed in the figure-of-four position, which puts tension on the adductor longus muscle A 3.0-cm vertical skin incision is made in the groin region, just inferior to the attachment of the adductor longus tendon at the symphysis pubis and

1 cm lateral to the symphysis pubis (Fig 2, A) Before the incision is made, 1:200,000 epinephrine-saline solution is injected to reduce skin bleeding After blunt dissection, the symphysis pubis is palpated and traced superiorly to the superior pubic ramus, while staying beneath the adductor longus and pectineus muscles, which are not divided

Once the superior pubic ramus has been palpated, a staphylorrha-phy elevator is placed into the obtu-rator foramen, and its location is confirmed fluoroscopically The soft tissue on the inferior, anterior, and posterior surfaces of the superior pubic ramus is gently elevated with the staphylorrhaphy elevator, and a radiolucent, malleable aluminum retractor is placed into the obturator foramen to protect the neurovascu-lar structures (Fig 2, B) A Cobb ele-vator is used to lift the lateral border

of the pectineus muscle so that a

5-mm, 30-degree endoscope and a soft-tissue sheath (Endopath, Ethi-con Endo-Surgery, Cincinnati, Ohio) may be perched on the anterior edge

of the superior pubic ramus (The

US Food and Drug Administration has not approved use of the sheath for this purpose Therefore, this is an

“off-label” use.) The endoscope has

a hood that keeps the soft tissue off the tip of the endoscope and allows bone visualization The overlying periosteum is incised and elevated with a tip-protected, long-handled

electrocautery device, which brings the bone into view A suction/irri-gator device is placed into the single portal to eliminate smoke and to wash the endoscope

Under endoscopic visualization, the cortex of the superior pubic ra-mus is opened with an osteotome 1

cm from the medial acetabular wall The osteotomy is completed with a pituitary rongeur under fluoroscopic control By tilting the C-arm 20 de-grees, one can obtain an internal oblique view, which provides opti-mal visualization of the superior pubic ramus It is important to resist the tendency for the bone cut to devi-ate ldevi-aterally over the acetabulum After completion of the osteotomy,

an osteotome is placed into the site and twisted to verify adequate bone mobility The resected bone from the rongeur is replaced into the osteot-omy site

Proceeding directly from the su-perior pubic ramus cut to the ischial cut is not recommended, because of the proximity of the vascular struc-tures (internal iliac artery and vein and obturator artery and veins) along the medial wall of the acetab-ulum The ischial cut is approached through the same skin incision as the pubic cut, but a new portal through the deep tissues to the is-chium must be created The sym-physis pubis is palpated through the original skin incision and is then followed inferiorly between the gracilis muscle (inferomedially) and the adductor brevis (superolat-erally) Finger dissection is used to proceed along the inferior pubic ramus in the plane between the obturator externus and adductor magnus muscles until the ischium

is reached The soft tissue is cleared off the ischium with a Cobb eleva-tor 1 to 2 cm inferior to the acetabu-lar teardrop The position should

be confirmed fluoroscopically, as it

is easy to stray from the ischium onto the femoral neck or lesser trochanter

Figure 1 The patient is placed on a

radio-lucent table in the figure-of-four position

for the initial groin incision The C-arm,

endoscopy monitor, and fluoroscopy

moni-tor are placed opposite the operating

sur-geon.

Fluoroscopic

C-arm

Endoscopy

monitor

Fluoroscopy

monitor

A radiolucent, malleable

alumi-num retractor is placed into the

ob-turator foramen on the medial side

of the ischium (Fig 2, C) The

soft-tissue endoscope is placed on the

lateral side of the ischium inferior to

the ischial spine The residual

peri-osteal soft tissue is cleared with a

tip-protected electrocautery device,

which exposes the cortical bone

The exact location is confirmed

fluo-roscopically, and a 0.5-inch

osteo-tome is used to open the cortex The

osteotomy is continued with straight

and angled pituitary rongeurs It is

important to avoid allowing the

direction of the osteotomy to deviate superiorly toward the hip joint as the depth of the cut increases The oste-otomy should be kept inferior to the ischial spine and the sacrospinous ligament (Fig 2, D) The ischium is

at least three times thicker than the superior pubic ramus and thus takes longer to cut

Once the cut has been completed, mobility is tested by twisting a 0.5-inch osteotome in the osteotomy site under endoscopic and fluoroscopic visualization Harvested bone is re-placed into the osteotomy site This completes the first two osteotomies,

which have been performed through the same 3.0-cm skin incision in the groin region

The surgeon can then approach the iliac osteotomy site percuta-neously or through a mini-open approach In the percutaneous approach to the ilium, a 3-cm verti-cal incision is made over the lateral gluteal muscles, midway between the anterior inferior iliac spine and the anterior superior iliac spine and about 5 cm posterior to the anterior superior iliac spine The gluteal muscles are split in line with their fibers until the outer table of the

A

D

B

E

C

F Figure 2 Technique of endoscopic pelvic osteotomy A, An incision is made in the groin crease, starting on the inferior surface of the

adductor longus tendon and running inferiorly 3 cm The incision for the percutaneous approach to the ilium is made over the lateral

gluteal muscles B, A malleable aluminum retractor is placed in the obturator foramen via the groin incision to protect the obturator

neu-rovascular bundle The endoscope is placed via the same groin incision and is perched on the anterior edge of the superior pubic ramus.

C, The malleable retractor is placed in the obturator foramen on the medial surface of the ischium, and the endoscope is placed on the

lat-eral surface of the ischium Both retractors are placed through the groin incision D, The ischial osteotomy should exit between the

sacrospinous and sacrotuberous ligaments, inferior to the ischial spine Retaining the connection of the sacrospinous ligament to the acetabular fragment appears to improve stability of the iliac fixation pins Due to the medial location of the ligament on the fragment,

lat-eralization of the rotated acetabulum is limited E, The sciatic nerve is protected with the malleable retractor in the sciatic notch The endoscope faces toward the malleable retractor The posterior half of the osteotomy is performed first with a burr F, The malleable

retractor is placed over the anterior edge of the ilium between the anterior superior iliac spine (ASIS) and the anterior inferior iliac spine (AIIS) The endoscope is flipped to face anteriorly, and the anterior half of the osteotomy is completed.

Groin

incision

Sacrotuberous ligament

Ischial osteotomy site Sacrospinous ligament

Iliac incision Endoscope

Malleable retractor

AIIS ASIS

Sciatic nerve

ilium is identified 2 cm superior to

the hip joint The incision is far

enough anterior that the inferior

branches of the superior gluteal

nerve and artery are avoided

The soft tissue is elevated

be-tween the anterior ilium and the

sci-atic notch In this area, there is

min-imal soft-tissue attachment to the

ilium, and the bone is easily cleared

A radiolucent, malleable aluminum

retractor is placed into the sciatic

notch, to protect the sciatic nerve

(Fig 2, E) A cut is made with a

high-speed burr under endoscopic and

fluoroscopic control This cut is the

most difficult to visualize because

of the splatter created by the burr

Once the posterior portion of the

osteotomy is complete, the

malle-able retractor is moved to the

ante-rior aspect of the pelvis between the

anterior superior iliac spine and the

anterior inferior iliac spine (Fig 2, F)

The position of the endoscope is

then reversed Before the osteotomy

is completed, two Schanz screws are

drilled into the supra-acetabular

bone under fluoroscopic guidance

On completion of the final

osteot-omy, the acetabulum is rotated

lat-erally into proper position with use

of the Schanz pins Anterior and

posterior coverage can be adjusted

through forward or backward

rota-tion of the two Schanz pins before

fixation Retroversion of the

acetab-ulum should be avoided The

pa-tient’s leg can be adducted across

the midline to improve rotation, but

the figure-of-four position should be

avoided, as it will externally rotate

(retrovert) the acetabulum A

struc-tural bone graft is usually not

neces-sary The iliac osteotomy is fixed

with two threaded Steinmann pins

or two large cannulated screws A

small cutdown should be made over

the iliac crest for pin fixation,

allow-ing visualization of pin or screw

passage between the inner and outer

iliac tables

The mini-open approach to the

iliac osteotomy is preferable when

30 to 40 degrees of increased cover-age is required It utilizes the stan-dard Salter approach made through

a limited 6-cm bikini-line incision

The iliac osteotomy cut can be made with a Gigli saw in young patients (less than age 10 years), but a sagit-tal saw and osteotome are often needed for older patients, because

of their thicker bone The mini-open approach also allows direct visualization of the fixation pins or screws A structural bone graft can

be cut from the ilium and placed into the osteotomy site if needed

An AP radiograph of the pelvis, rather than a fluoroscopic image, is required to judge adequate acetabu-lar rotation of the osteotomy with ref-erence to the entire pelvis This film should show a center-edge angle of

at least 25 degrees and a horizontal sourcil Neither a wound drain nor prophylaxis for heterotopic ossifica-tion is usually required

Patients can start crutch walking

on postoperative day 1 with touch-down weight bearing Once there is radiographic evidence of healing (usually 2 to 3 months postoperative-ly), full weight bearing is allowed

Originally, the Steinmann pins were removed, but they can be cut flush with the bone and left in place

Preclinical Studies

This technique was developed by performing the procedure on human cadaver hips and anesthetized pigs

In the cadaver group, acetabular rota-tion averaged 31 degrees In that study, there was no joint penetra-tion, and the pin fixation was stable

on manual testing Stability of the fragment was enhanced by leaving the sacrospinous ligament intact to act as a medial stabilizer and to pre-vent lateral migration of the acetab-ulum with rotation (Fig 2, D) Cutting the ischial spine or sacrospinous liga-ment appeared to make pin or screw fixation more tenuous There was no

apparent damage to neurovascular structures The sciatic nerve was at least 1 cm posterior to the ischial cut, and was well protected by the short hip external rotators The ob-turator nerve and artery lie 4 to 8

mm posterior to the superior pubic ramus and are well protected by the malleable retractor

In the anesthetized pig group, bleeding blocked visualization when, after completion of the supe-rior pubic ramus osteotomy, dissec-tion proceeded directly to the

ischi-um across the medial wall of the acetabulum There are abundant vascular structures in this area, which can be completely avoided

by creating a separate deep portal from the symphysis pubis to the ischium

Early Clinical Results

In a study of 10 patients treated with endoscopic pelvic osteotomy (5 with developmental dysplasia of the hip, 2 with spina bifida, 2 with Legg-Perthes disease, and 1 with Down’s syndrome), the center-edge angle improved from 2 degrees (range, –15 to +13 degrees) preoper-atively to 38 degrees (range, 20 to 56 degrees) postoperatively (Fig 3) The acetabular angle improved from 50 degrees (range, 38 to 55 degrees) preoperatively to 27 de-grees (range, 19 to 42 dede-grees) post-operatively The mean operative time was 289 minutes; the mean estimated blood loss was 325 mL; and the average period of hospital-ization was 3.5 days (range, 1 to 7 days) Preoperatively, patients were asymptomatic (radiographic dys-plasia) or had mild hip pain Post-operatively, 9 patients ambulated without pain or a limp at an average follow-up interval of 17 months (range, 7 to 38 months)

There were no neurovascular complications associated with the endoscopic osteotomy cuts One

major complication occurred when a

percutaneously placed iliac fixation

pin slid down the medial wall of the

ilium during insertion, injuring the

ureter and the bowel Two patients

had asymptomatic nonunion of

either the ischial or the superior

pubic osteotomy site

Comparison With Open

Osteotomy

Endoscopic pelvic osteotomy is a

potential alternative to open pelvic

osteotomy for treating acetabular

dysplasia The procedure appears

to give radiographic results similar

to those of open pelvic osteotomies

(Table 1)

The technique is very demanding

and requires both cadaveric and

animal laboratory experience A

soft-tissue endoscope sheath is

nec-essary, as well as fluoroscopic

equipment The operative time

re-quired for the procedure is about

equal to that for an open pelvic

os-teotomy Improved

instrumenta-tion and further experience will

probably reduce surgical time

Most patients who have undergone

the endoscopic procedure have had

minimal postoperative pain and

occasionally have initiated crutch walking (including stair climbing)

on postoperative day 1

The endoscopic pelvic osteotomy involves small incisions, minimum bone dissection, and no tendon transection Besides reduced tissue dissection, its advantage over the Steel triple osteotomy8is that the pelvic bone cuts are closer to the acetabulum, which makes rotation easier The advantage over the Tönnis triple innominate osteot-omy7 is that the iliac spine is not cut, allowing the sacrospinous liga-ment to be used as a checkrein against lateralization of the acetabu-lum (Fig 2, D) Retention of the lig-ament adds stability to the fixation construct, preventing postoperative loss of fixation The endoscope seems to be most advantageous for the superior pubic ramus and is-chial osteotomy, due to the depth and small size of the bones After making the first two lower endo-scopic cuts, it may be safer and easier

to use an open Salter approach to the iliac osteotomy, especially early

in the surgeon’s experience with the endoscope

Unlike the Bernese periacetabu-lar osteotomy14,15and the spherical osteotomy,16-20the endoscopic triple

osteotomy does not disturb the tri-radiate cartilage and may be per-formed before skeletal maturity of the patient This approach does not allow easy access for arthrotomy and repair of an acetabular rim frac-ture The endoscopic technique is contraindicated for patients with an acetabular rim syndrome

Current indications for the endo-scopic triple pelvic osteotomy are a center-edge angle less than 16 de-grees, evidence of concentric reduc-tion on an abducreduc-tion radiograph, and the absence of mechanical symptoms indicating a possible acetabular rim syndrome This technique is most applicable to ado-lescent patients; its role in adults has yet to be determined

Summary

Early results demonstrate that en-doscopic triple innominate osteot-omy is a technically demanding but feasible procedure after the sur-geon has gained sufficient knowl-edge of the anatomy and adequate practice This procedure has a steep learning curve, requiring extensive surgical experience The approach provides excellent acetabular

Figure 3 Radiographs of a 13-year-old girl with residual developmental dysplasia of the hip (treated surgically in childhood) and

myelomeningocele A, Preoperative film shows left hip subluxation and a center-edge angle of 7 degrees B, Film obtained immediately after endoscopic osteotomy shows that coverage has been increased C, Film obtained 6 months after procedure shows healing of the iliac

and superior pubic ramus osteotomy sites.

tion and femoral head coverage,

similar to the reported results with

open triple, periacetabular, and

spherical osteotomies With

re-duced surgical morbidity,

endo-scopic techniques may make pelvic osteotomy a more attractive proce-dure for adolescent and young adult patients with early hip arthri-tis or potential arthriarthri-tis secondary

to a dysplastic acetabulum Further experience and clinical follow-up results are required before this pro-cedure can be recommended as a standard technique

Table 1

Clinical Results With Use of Open or Endoscopic Pelvic Osteotomy

* Data for only group I hips (dysplastic but concentrically reduced) and group II hips (dysplastic and subluxated) were considered Group III hips (frankly dislocated) were excluded because they were not comparable to the hips in the other studies.

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