Journal of the American Academy of Orthopaedic Surgeons 150 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, 14,15 and 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 Perspectives on Modern Orthopaedics Eric J. Wall, MD, et al Vol 9, No 3, May/June 2001 151 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 laterally 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 Endoscopic Pelvic Osteotomy Journal of the American Academy of Orthopaedic Surgeons 152 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 Eric J. Wall, MD, et al Vol 9, No 3, May/June 2001 153 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 degrees) 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 Endoscopic Pelvic Osteotomy Journal of the American Academy of Orthopaedic Surgeons 154 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 osteotomy 8 is that the pelvic bone cuts are closer to the acetabulum, which makes rotation easier. The advantage over the Tönnis triple innominate osteot- omy 7 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 osteotomy 14,15 and the spherical osteotomy, 16-20 the 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 abduction 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 rota- A B C 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. Eric J. Wall, MD, et al Vol 9, No 3, May/June 2001 155 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 arthritis 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 Change in Change in Type of No. of Hips/ Center-Edge Acetabular Author(s) Osteotomy No. of Patients Angle Angle Sutherland and Moore 5 Double 21/21 15° 12° Hsin et al 13 Triple 22/17 17° . . . de Kleuver et al 6 Triple 48/41 19° 12° Szepesi et al 9 Triple 8/8 23° . . . Tönnis et al 7 Triple 22/22 25.7° * 18.7° * Trousdale et al 15 Periacetabular 42/42 28° . . . Guille et al 10 Triple 11/10 30° 16° Ganz et al 14 Periacetabular 75/63 31° . . . Millis et al 16 Spherical 43/40 31° . . . Kumar et al 12 Triple 12/11 31.6° . . . Matsui et al 20 Spherical 25/23 34° . . . Faciszewski et al 11 Triple 56/44 33° 15° Wagner 17 Spherical 88/76 35.2° . . . Wall et al (unpublished data) Endoscopic 10/10 36° 23° Haynes et al 19 Dial spherical 13/13 40.7° . . . Ninomiya 18 Spherical 41/39 46.7° . . . * 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. References 1. Millis MB, Poss R, Murphy SB: Oste- otomies of the hip in the prevention and treatment of osteoarthritis. Instr Course Lect 1992;41:145-154. 2. Murphy SB, Ganz R, Müller ME: The prognosis in untreated dysplasia of the hip: A study of radiographic factors that predict the outcome. J Bone Joint Surg Am 1995;77:985-989. 3. Wedge JH, Wasylenko MJ: The natural history of congenital disease of the hip. J Bone Joint Surg Br 1979;61:334-338. 4. Weinstein SL: Natural history of con- genital hip dislocation (CDH) and hip dysplasia. Clin Orthop 1987;225:62-76. 5. Sutherland DH, Moore M: Clinical and radiographic outcome of patients treated with double innominate osteotomy for congenital hip dyspla- sia. J Pediatr Orthop 1991;11:143-148. 6. de Kleuver M, Kooijman MAP, Pavlov PW, Veth RPH: Triple osteotomy of the pelvis for acetabular dysplasia: Results at 8 to 15 years. J Bone Joint Surg Br 1997;79:225-229. 7. Tönnis D, Behrens K, Tscharani F: A modified technique of the triple pelvic osteotomy: Early results. J Pediatr Orthop 1981;1:241-249. 8. Steel HH: Triple osteotomy of the innominate bone, in Tachdjian MO (ed): Congenital Dislocation of the Hip. New York: Churchill Livingstone, 1982, pp 567-594. 9. Szepesi K, Dávid T, Rigó J, Szücs G: A new surgical approach in 8 cases of polygonal triple pelvic osteotomy. Acta Orthop Scand 1993;64:519-521. 10. 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Trousdale RT, Ekkernkamp A, Ganz R, Wallrichs SL: Periacetabular and in- tertrochanteric osteotomy for the treat- ment of osteoarthrosis in dysplastic hips. J Bone Joint Surg Am 1995;77:73-85. 16. Millis MB, Kaelin AJ, Schluntz K, Curtis B, Hey L, Hall JE: Spherical acetabular osteotomy for treatment of acetabular dysplasia in adolescents and young adults. J Pediatr Orthop B 1994;3:47-53. 17. Wagner H: Experiences with spheri- cal acetabular osteotomy for the cor- rection of the dysplastic acetabulum, in Weil UH (ed): Acetabular Dysplasia: Skeletal Dysplasias in Childhood. New York: Springer-Verlag, 1978, vol 2, pp 131-145. 18. Ninomiya S: Rotational acetabular osteotomy for the severely dysplastic hip in the adolescent and adult. Clin Orthop 1989;247:127-137. 19. Haynes RJ, Barnes DA, Ray RB: Dial osteotomy of the acetabulum: A tribute to Richard E. Eppright, MD (1925- 1997). Presented at the Annual Meet- ing of the American Academy of Pediatrics Section on Orthopaedics, San Francisco, Calif, October 17-18, 1998. 20. Matsui M, Masuhara K, Nakata K, Nishii T, Sugano N, Ochi T: Early de- terioration after modified rotational acetabular osteotomy for the dysplas- tic hip. J Bone Joint Surg Br 1997;79: 220-224.