CHAPTER OUTLINE
Developmental Dysplasia of the Hip 188
Previous Intertrochanteric Osteotomy 190
Surgical Considerations for Corrective Osteotomy Associated with Primary Total Hip Arthroplasty 191
Femoral Deformity Associated with Failed Total Hip Arthroplasty 192
Summary 194
Femoral deformities pose many technical challenges for the surgeon. Deformities can make total hip arthroplasty exposure difficult, can increase the risk of femoral fracture or perforation, and can lead to implant malposition. Deformities may, in some cases, compromise implant fixation. Hip instability caused by bony impingement or implant malposition may occur in hips with femoral deformity. Finally, deformity can alter hip biomechanics, thereby causing problems with abductor power and limp.
Proximal femoral deformities, although uncommon, are not rare in patients who require total hip arthroplasty and occur for many reasons. Proximal femoral deformity may be present as a result of developmental problems such as developmental dysplasia of the hip (DDH) or congenital coxa vara or be secondary and occur after proximal femoral osteotomy or failed total hip arthroplasty. In addition, deformity of the proximal femur may be the result of proximal femoral fracture malunion or nonunion, Paget disease of the femur, and femoral fibrous dysplasia. Berry has proposed an anatomic classification based on the deformity site: greater trochanter, femoral neck, metaphyseal level, and diaphyseal level. Further categorization can be established by the geometry of the deformity: angular, rotational or translational, abnormal bone size, or a combination thereof.
The surgeon faces certain technical difficulties during primary or revision total hip arthroplasty in patients with distorted proximal femoral anatomy. When planning hip replacement in these patients, three surgical attitudes are possible. First, if the deformity is very proximal it simply can be eliminated. Second, if the deformity is not very severe, the surgeon may be able to adapt the procedure to the altered anatomy by modifying the technique or the implant. Third, there are situations in which the deformity is so significant that the surgeon needs to correct it, either simultaneously with the arthroplasty or as a preliminary step before arthroplasty.
Careful preoperative planning helps predict which of these attitudes may be best suited to the situation. Access to a wide range of implants helps the surgeon treat unique femoral geometries. Implants fixed in the diaphysis allow some proximal femoral deformities to be bypassed. Modular or custom implants simplify treatment of certain deformities. If concomitant osteotomy to affect deformity correction is necessary, the requisites of maintaining the blood supply of the bony fragments, achieving satisfactory fixation of the osteotomy (using the implant and/or adjunctive fixation), and obtaining implant stability must be met.
In this chapter the most frequent causes of proximal femoral deformity are addressed and the specific needs and techniques applicable to each situation are presented.
DEVELOPMENTAL DYSPLASIA OF THE HIP
In patients with DDH there are two conditions that concern the proximal femur: without previous surgery or with previous femoral osteotomy.
DDH without Previous Surgery
There are two main technical problems associated with hip joint replacement in severely dysplastic or dislocated hips. The first involves the proximal femur, which typically shows anteversion exceeding 20 to 30 degrees. If cemented replacement is chosen, a small femoral component is used to reduce the anteversion to a more physiologic level. The void left in the anterior metaphyseal area then is filled with cement. However, cement fixation of the femoral component carries a significant incidence of symptomatic mechanical failure in dysplastic hips of young persons with a high level of physical activity. This has led most surgeons to use uncemented femoral components in these young patients. However, using an uncemented metaphyseal-filling femoral component may result in the insertion of an implant with an unacceptable degree of anteversion that could compromise joint stability; if a smaller uncemented metaphyseal-filling component is used to “counter” the increased anteversion, prosthetic fixation may be compromised. Often, distally fixed uncemented components with a modified narrower proximal geometry or modular components allow the surgeon to “cheat” the anatomy and provide reliable uncemented fixation.
An additional problem is the position of the acetabular component, which must be seated near the anatomic center of rotation of the hip to obtain reliable fixation and to achieve the abductor strength necessary to balance the pelvis. Especially in hips with high dislocation, shortening procedures of the femur are valuable to bring the prosthetic head low enough for reduction. In these complex cases, a reasonable alternative is the use of a proximal femoral subtrochanteric osteotomy combined with distal advancement of the greater trochanter or segmental metaphyseal shortening osteoplasty.
DDH with Previous Femoral Osteotomy
Technical problems outlined earlier are significantly worse if the proximal femoral anatomy has been altered by previous osteotomy, the most common being the subtrochanteric Schanz osteotomy. If the proximal femoral anatomy is significantly altered by a previous osteotomy, a canal realignment procedure, accompanied if necessary by shortening, should be done concomitantly with the replacement. This technique is described here and provides predictable results when combined with the use of uncemented femoral stems. Because of the frequently very narrow diameter of the femoral canal in patients with DDH, special stems may at times be necessary.
Satisfactory results have been reported in patients with DDH and a previous Schanz osteotomy treated by uncemented total hip arthroplasty with femoral shortening and advancement of the greater trochanter. The incidence of complications is greater than in primary total hip arthroplasties, however.
Total hip arthroplasty in combination with a subtrochanteric double chevron derotation osteotomy showed satisfactory early results in the treatment of complete congenital dislocation of the hip in adults. In all seven cases, an uncemented femoral component was inserted. There have been no nonunions, dislocations, or nerve palsies. The average femoral shortening was 4.5 cm (range: 3.2-7.1 cm), and the average limb lengthening was 1.2 cm (range: −0.3-1.9 cm).
The results of total hip arthroplasty for DDH with different forms of femoral osteotomy have been reported with short- to midterm follow-up. Reikeraas and associates reported on 25 dislocated hips that were treated with femoral shortening through a subtrochanteric transverse osteotomy with an uncemented stem. After follow-up of 3 to 7 years, one delayed union and one malunion were reported but there were no mechanical failures.
The senior author and his colleagues reported 14 primary hip replacements in patients with DDH, 8 of them with previous failed proximal femoral osteotomy. Shortening and correction of angular and rotational deformities were performed at the osteotomy site. Two of the four patients treated with femoral shortening required revision surgery for osteotomy nonunion and aseptic loosening of the femoral component. Overall, subtrochanteric osteotomy has provided satisfactory results in at least 80% of cases. However, malunion and nonunion occasionally occur and can be associated with fatigue failure of the stem or aseptic loosening.
Yasgur and associates reported the results of a transverse osteotomy, for subtrochanteric femoral shortening and derotation, in eight patients with Crowe type IV hips who had replacement with fully coated (six hips), modular (one hip), or cemented (two hips) stems combined with a transverse subtrochanteric osteotomy for shortening and retroversion. At a mean follow-up of 3.6 years (range: 2 to 7 years), eight patients were followed for an average of 43 months with good to excellent results in seven. Eight of nine osteotomies (89%) demonstrated radiographic evidence of healing at an average of 5 months. One hip required revision, and an asymptomatic patient developed radiographic nonunion.
Chareancholvanich and colleagues reported 15 hips in 11 patients with complete congenital dislocation treated by total hip arthroplasty and femoral shortening with a subtrochanteric double chevron derotation osteotomy at 5.5 years. An excellent result in 5 and a good result in 7 were recorded (80% success rate). The location of the hip center was lowered by a mean of 8.3 cm (range: 5.7-10.4 cm). Leg length discrepancy in 7 patients with unilateral involvement was reduced from a mean of 3.9 cm (range: 1.7-8.2 cm) before surgery to a mean of 1.4 cm at the latest follow-up (range: 0-4 cm). The Trendelenburg sign was corrected from a positive preoperative status to a negative postoperative status in 8 of 10 hips. The only complications were a supracondylar fracture below the femoral component and loosening of the cemented titanium-backed acetabular component 1.5 years after surgery.
Uncemented femoral fixation in conjunction with a subtrochanteric derotational osteotomy has been described in a small series of patients by Zadeh and coworkers. In seven patients with a mean age of 49 years, an uncemented femoral prosthesis in conjunction with subtrochanteric derotational osteotomy allowed the restoration of the normal proximal femoral anatomy, including the abductor muscle lever arm, without resorting to greater trochanteric transfer. Correction of the excessive femoral anteversion avoided the tendency for postoperative anterior instability. A computer-assisted design/computer-assisted manufacturer design included a close intramedullary proximal fit, with collar, lateral flare, and hydroxyapatite coating to achieve early proximal fixation and a longitudinally cutting fluted stem to provide immediate rotational stability across the osteotomy site. With a mean follow-up period of 31 months, all cases had a satisfactory outcome with evidence of union at the osteotomy site.
More recently, a new technique of subtrochanteric shortening with the prosthesis in situ has been described. The technique minimized complications, allowed correction of severe femoral neck anteversion, and gave excellent rotational stability, while preserving the proximal femur for better press-fit uncemented fixation. Significant pain relief and functional improvement were reported in nine patients, and all osteotomies appeared to be healed on radiographs by 12 weeks.
Perka and colleagues, in 2000, described the implantation of an uncemented straight stem in 15 patients using a simultaneous, derotating, and shortening osteotomy. Advantages included a shorter duration of surgery, a lower complication rate, and a more rapid consolidation of the osteotomy. Femur fractures, pseudarthroses, stem loosening, paresis, and deep infections were not present at 4 years.
Recently, Eskelinen and associates reported 68 uncemented total hip replacements in 56 consecutive patients with high congenital hip dislocation. The cup was placed at the level of the true acetabulum, and a shortening osteotomy of the proximal part of the femur and distal advancement of the greater trochanter were performed in 90% of the hips. At a mean follow-up of 12.3 years, the rate of survival for the femoral components with congenital hip dislocation, with revision because of aseptic loosening as the end point, was 98.4% at 10 years.
PREVIOUS INTERTROCHANTERIC OSTEOTOMY
Intertrochanteric femoral osteotomy can cause significant deformity in the metaphyseal area of the femur; it is logical to expect that conversion to hip replacement can be more difficult and, therefore, one should expect more perioperative complications and also an influence on the quality of the long-term results. The role of cortical defects caused by screw removal in causing prosthetic loosening is uncertain but seems to be implicated in some cases. The presence of cortical holes can decrease the quality of cement-bone interdigitation, and the small penetrations of cement through the screw holes may act as stress risers in the mantle and facilitate loosening. Also in cases of uncemented stem implantation, the presence of screw holes could increase the possibility of intraoperative femoral fracture.
The indications for intertrochanteric osteotomy should be strictly followed and the procedure executed, taking care that the mechanical axis of the limb is maintained and the anatomy of the proximal femur is not distorted. Routine hardware removal after osteotomy healing is simple and sensible. When conversion to hip replacement becomes necessary, proper preoperative planning will help determine whether a two-stage procedure is advisable, whether the altered anatomy can be accommodated by the prosthesis, or whether an osteotomy to “undo” the previous osteotomy will be needed. In cases of previous varus intertrochanteric osteotomy, the greater trochanter is often located directly over the femoral canal and a trochanteric osteotomy or slide is necessary to avoid damage to the abductors during the operation and to restore the hip joint mechanics.
Dupont and Charnley first reported on 121 proximal femoral osteotomies converted to total hip arthroplasty and followed for 1 year. Results with this short follow-up were satisfactory, with 87% of patients having no pain and significantly improved range of motion. No data were given for complications, long-term loosening, or revision rates.
Benke and associates reviewed 105 femoral osteotomies converted to cemented total hip arthroplasty and followed a mean of 4.7 years. Eighty-two percent of patients had little or no pain, and 75% could walk long distances. The infection rate was 8.6%, and technical difficulties, including broken screws and femoral shaft fractures, occurred in 17.1%. Long-term revision or radiographic loosening rates were not provided.
DeCoster and colleagues reported three cases in which a biplanar reosteotomy at the level of the lesser trochanter was needed to correct the angular deformity from a previous Southwick osteotomy for slipped capital femoral epiphysis. With an average of 3 years of follow-up, all patients had union of the osteotomy and a successful clinical result. All patients are doing well at 10-year follow-up.
Ferguson and associates reported 305 total hip arthroplasties in 290 patients who had a previous failed intertrochanteric osteotomy; 215 hips were followed a minimum of 5 years. The femoral component was always cemented without a concomitant femoral osteotomy, although at times this necessitated the use of a straight or specially curved component. There was a high incidence of operative technical problems (23%), complications (24.9%), and aseptic revisions (14.9%). Femoral fracture or perforation occurred in 7 of 307 hips.
Inferior survival of cemented total hip arthroplasty has been reported after previous femoral osteotomy. Boos and colleagues reported a comparison of 74 total hip arthroplasties after femoral osteotomy with a diagnosis-matched control group of 74 primary procedures performed during the same period. Within a follow-up from 5 to 10 years, no significant difference was found in the rate of perioperative complications (11% each) or in septic (8% vs. 3%) and aseptic (4% each) revision. Improved survival was observed in the group without previous osteotomy (90% vs. 82%). The only significant differences were a higher rate of trochanteric osteotomy (88% vs. 14%) and a longer operating time in the osteotomy group. The authors concluded that total hip arthroplasty after previous osteotomy is technically more demanding but not necessarily associated with a higher rate of complications.
Shinar and Harris reviewed 22 primary cemented total hip arthroplasties performed by a single surgeon after failed proximal femoral osteotomies and followed an average of 15.8 years. Eight reconstructions required custom miniature or calcar replacement components. Two of 19 femoral components (10.5%) were revised for aseptic loosening, and two additional femoral components were loose. Intertrochanteric osteotomy in general did not affect the expected excellent results of the femoral component using modern cementing techniques. Severe deformity after subtrochanteric osteotomy, however, did adversely affect the outcome.
Uncemented implants also may be at risk for loosening in patients with femoral deformity primarily because deformity can compromise the initial fit and fixation of the prosthesis to bone. There are limited data to evaluate the effect femoral deformity has on reliability and durability of uncemented femoral fixation. Breusch and coworkers reported 48 hips in 45 patients who had undergone conversion total hip arthroplasty with uncemented stems for a failed intertrochanteric osteotomy of the hip after a mean of 12 years. Mean time of follow-up was 11 years. Three patients (three hips) underwent femoral revision—one for infection and two for aseptic loosening of the stem. Survival of the stem was 94% at 10 years, and survival with femoral revision for aseptic loosening as an endpoint was 96%. The median Harris Hip Score at follow-up was 80 points. Radiolucent lines in Gruen zones 1 and 7 were present in 14% and 18% of hips, respectively. There was no radiographic evidence of femoral osteolysis, stress-shielding, or loosening.
In cases of diastrophic dysplasia, osteogenesis imperfecta, or fibrous dysplasia with a significant femoral deformity, osteotomy at one or more levels may be needed to realign the femoral canal and allow insertion of a femoral prosthesis. Peltonen and coworkers described three cases of diastrophic dysplasia in which a one-level shortening femoral osteotomy combined with a greater trochanter transfer and tenotomies gave good results. A two-level osteotomy of the proximal and distal femur was required to restore the distorted femoral canal anatomy in one of our patients with fibrous dysplasia who had undergone a previous proximal femoral osteotomy.
In cases of angular femoral deformity (Paget disease) that cannot be bypassed with a long-stemmed femoral component, a corrective osteotomy may be applicable. The apex of the deformity is usually recommended as the osteotomy site, and a biplanar osteotomy is most often used.
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