History

The patient is a 25-year-old law student with a history of Larsen’s syndrome and bilateral hip dysplasia. She had undergone a successful right total hip arthroplasty two years ago because of worsening hip pain. She now presented with increasingly disabling left hip pain, intermittent but severe, which was frequently present at rest and at night as well as with any attempted activity. Her symptoms had progressed to the point that she could only ambulate one block outdoors, despite using a cane full-time. Past medical history is notable for 38 surgical procedures (related to her Larsen’s Syndrome) involving numerous joints and performed prior to age 5 but is otherwise noncontributory.

On examination, the patient had the facial dysmorphism characteristic of Larsen’s Syndrome. She ambulated with a severely antalgic gait on the left. The left lower extremity was approximately 2cm shorter than the right. The left hip had 85 degrees of flexion, minimal internal and external rotation, and 30 degrees of abduction, with a positive Stinchfield test. She was noted to have multiple other deformities involving both knees, elbows, and feet, as well as numerous well-healed surgical incisions. Neurovascular examination of both lower extremities was normal.

AP (Figure 1) and lateral (Figure 2) views of the left hip reveal a severely dysplastic acetabulum. The femoral head is flattened, dislocated superiorly, and shows severe degenerative changes. A CT scan (Figure 3) shows the femoral head articulating with a pseudoacetabulum (in the ilium). The femoral neck-shaft angle is in excessive valgus, and there is varus bowing of the proximal femoral diaphysis as well.

Diagnosis

Severe left hip dysplasia (associated with Larsen’s Syndrome) with severe secondary osteoarthritis

Discussion

Developmental dysplasia of the hip (DDH) is a disorder characterized by disturbance of development of the normal hip joint. The severity of the deformity ranges from a shallow acetabulum with lateral subluxation of the femoral head to complete superior dislocation of the femoral head, which may articulate with a “pseudoacetabulum” in the ilium. On the acetabular side, characteristic anatomic abnormalities include a shallow acetabulum, often with deficient anterior and superior bone stock, while typical femoral abnormalities include a small femoral head, excessive anteversion and valgus angulation, and a small, tapered femoral canal [5]. In addition, soft-tissue structures about the hip, including muscles, nerves, and blood vessels, may be severly contracted, particularly in the case of a “high-riding” dislocated hip. These anatomic features make total hip arthroplasty for the treatment of DDH a potentially challenging endeavor.

In 1950, Larsen described a syndrome consisting of multiple joint dislocations in conjuction with a characteristic facial dysmorphism (hypertelorism, flattening of the base of the nose, and bulging of the forehead) [7]. Although knee dislocation is a constant feature of Larsen’s Syndrome, 40-60% of cases reported in the literature have also had unilateral or bilateral hip dislocation or subluxation, with the severity of the hip dysplasia paralleling the severity of the knee deformity [8]. Laville noted that hip dysplasia in patients with Larsen’s Syndrome is typically more refractory to closed treatment than non-syndromic DDH; the Pavlik harness, a mainstay of treatment of DDH in infants, was successful in only 50% of these patients [8]. He noted particularly “disappointing” results in patients with bilateral dislocation.

Ideally, DDH is diagnosed in infancy, when closed treatment methods may be used in order to maintain concentric reduction of the hip and allow further development of the joint to proceed normally. In some cases, open reduction is required, possibly supplemented by pelvic and/or femoral osteotomies. In some patients, however, the process is refractory to treatment or the diagnosis is missed until after skeletal maturity. These patients may present in adulthood, particularly once secondary degenerative changes have developed in their anatomically abnormal hip joint. In DDH with symptomatic secondary osteoarthritis, total hip arthroplasty more reliably results in pain relief and improved function than joint-sparing techniques such as osteotomy [5,12]. The long-term results of THR in the setting of DDH, however, are inferior to THR performed for primary osteoarthritis, most likely because of the abnormal anatomy as well as younger age of the DDH patients at the time of surgery.

Several classification systems have been developed to grade the severity of DDH. One of the most popular is that of Crowe et al [4], which ranges from Type I (superior migration of the femoral head <50% of its diameter) to Type IV (>100% superior migration). The Crowe classification has been shown to have prognostic value in predicting the outcome of THR in DDH patients [2]; the worst functional outcomes and highest complication rates are seen in Crowe Type IV hips, particularly if a pseudoacetabulum has developed (as is the case in this patient).

Acetabular reconstruction during THR for DDH can be successfully performed using a cementless component [1]. However, in the case of a completely dislocated hip, the optimal placement of the acetabular component remains controversial. One option is to place the prosthesis in an abnormally proximal position (“high hip center”) in order to obtain better lateral bone coverage and avoid excessive tension on the contracted soft-tissue structures [12]. However, some studies have found unacceptably high loosening rates with superior placement of the acetabulum [9], suggesting that the hip center be restored to its anatomic position if at all possible. Even with an extra-small component, this may leave the lateral portion of the component unsupported by host bone. There is currently no clear consensus as to the maximum amount of the cup which may be left uncovered without compromising stability of the component [5].

On the femoral side, extra-small “dysplasia components” may be needed because of the typically narrow diameter of the femoral diaphysis. In addition, a femoral osteotomy may be indicated for several reasons. First, it allows the femur to be shortened in order to protect the sciatic nerve, the risk of injury to which increases significantly if the limb is lengthened more than 4cm [5]. This is a particular concern if the acetabulum is brought down to its anatomic level in a patient with a completely dislocated hip. Second, an osteotomy allows correction of the angular and rotational deformities of the proximal femur which are typically present in DDH. Placing the osteotomy at the subtrochanteric level allows it to be performed via the same approach as used for the arthroplasty and enables the correction to be performed at or near the apex of the deformity [6]. Preoperative templating is crucial in order to determine the appropriate location, angle, and extent of the osteotomy.

Several techniques of performing a subtrochanteric femoral osteotomy have been described in the literature. Reikeraas [11] used a simple transverse osteotomy and obtained fixation by implanting an extensively porous-coated stem; 96% good or excellent results were reported at 3-7 year follow-up with this technique. Some authors advocate reinforcing the osteotomy site with a cortical strut graft and cables [13]. Alternatively, chevron or step-cut osteotomies have also been described [3,10], but they potentially do not allow as much correction of rotational deformity of the femur.

This patient presented with severe hip osteoarthritis secondary to hip dysplasia associated with Larsen’s Syndrome. The degree of hip dislocation as well as the femoral abnormalities presented a challenging reconstructive problem. The acetabulum was successfully reconstructed at its anatomic position using an extra-small cementless component. A subtrochanteric femoral shortening osteotomy allowed correction of the angular and rotational deformities of the femur as well as anatomic restoration of the hip center without placing undue tension on the neurovascular structures about the hip.

Clinical Course

Because of the patient’s severe disability due to her symptomatic left hip, and her excellent outcome after total hip replacement on the opposite side, it was recommended that she undergo a left THR. It was discussed with the patient that due to her abnormal anatomy, she might require bone grafting or other means of supplementing the acetabular reconstruction and possibly a femoral osteotomy to allow adequate mobilization of the femur and correct the angular deformity. She elected to proceed.

The modified Hardinge direct lateral approach to the hip was used. Significant scarring was noted about the hip capsule. In order to gain sufficient access to the hip, it was necessary to perform a fractional lengthening of the iliopsoas tendon and to completely detach the gluteus medius and minimus from the greater trochanter. The vastus lateralis was elevated off the femur, and a subtrochanteric femoral osteotomy was performed at the apex of the deformity. A second osteotomy was performed in order to allow the varus deformity to be corrected and to allow mobilization of the femur without placing excessive tension on the sciatic nerve. Once the femur was adequately mobilized, the articulation of the femoral head with the pseudoacetabulum was exposed.

The true acetabulum was then located, debrided of soft tissue, and reamed up to 41mm using power reamers. A porous-coated cup was implanted and had good bony coverage superiorly without the need for bone grafting. The femoral canal was broached and an extensively porous-coated stem implanted; solid fixation between the prosthesis and bone was obtained both proximally and distally to the osteotomy site. The acetabular liner and femoral head were implanted, and the wound was closed in the usual fashion.

Postoperatively, the patient has had good relief of her hip pain. Radiographs (Figures 4,5) show good alignment and apposition of the femoral segments and good lateral coverage of the acetabular component. At one year follow-up, patient continues to have an excellent result.

Figure 4

Figure 5

References

1. Anderson MJ, Harris WH. Total hip arthroplasty with insertion of the acetabular component without cement in hips with total congenital dislocation or marked congenital dysplasia. J Bone Joint Surg [Am] 81-A:347-354 (1999).
2. Cameron HU, Botsford DJ, Park YS. Influence of the Crowe rating on the outcome of total hip arthroplasty in congenital hip dysplasia. J Arthroplasty 11:582-587 (1996).
3. Chareancholvanich K, Becker DA, Gustilo RB. Treatment of congenital dislocated hip by arthroplasty with femoral shortening. Clin Orthop Rel Res 360:127-135 (1999).
4. Crowe JF, Mani VJ, Ranawat CS. Total hip replacement in congenital dislocation and dysplasi of the hip. J Bone Joint Surg [Am] 61-A:15-23 (1979).
5. Haddad FS, Masri BA, Garbuz DS, Duncan CP. Primary total replacement of the dysplastic hip. AAOS Instructional Course Lectures 49:23-39 (2000).
6. Holtgrewe JL, Hungerford DS. Primary and revision total hip replacement without cement and with associated femoral osteotomy. J Bone Joint Surg [Am] 71-A:1487-1495 (1989).
7. Larsen LJ, Schottstaedt ER, Bost FC. Multiple congenital dislocations associated with characteristic facial abnormality. J Pediatr 37:574-581 (1950).
8. Laville JM, Lakermance P, Limouzy F. Larsen’s Syndrome: Review of the literature and analysis of thirty-eight cases. J Pediatr Orthop 14:63-73 (1994).
9. Pagnano MW, Hanssen AD, Lewallen DG, Shaughnessy WJ. The effect of superior placement of the acetabular component on the rate of loosening after total hip arthroplasty: Long-term results in patients who have Crowe type-II congenital dysplasia of the hip. J Bone Joint Surg [Am] 78-A:1004-1014 (1996).
10. Papagelopoulos PJ, Trousdale RT, Lewallen DG.  Total hip arthroplasty with femoral osteotomy for proximal femoral deformity.  Clin Orthop Rel Res 332:151-162 (1996).
11. Reikeraas O, Lereim P, Gabor I, Gunderson R, Bjerkreim I.  Femoral shortening in total arthroplasty for completely dislocated hips:  3-7 year results in 25 cases.  Acta Orthop Scand 67:33-36 (1996).
12. Sanchez-Sotelo J, Berry DJ, Trousdale RT, Cabanela ME.  Surgical treatment of developmental dysplasia of the hip in adults:  II. Arthroplasty options.  J Amer Acad Orthop Surg 10:334-344 (2002).
13. Yasgur DJ, Stuchin SA, Adler EM, DiCesare PE.  Subtrochanteric femoral shortening osteotomy in total hip arthroplasty for high-riding developmental dislocation of the hip.  J Arthroplasty 12:880-888 (1997).

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