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Total Hip Arthroplasty for Bilaterally Ankylosed Hips
The Journal of Arthroplasty Vol. 22 No. 7 2007
Total Hip Arthroplasty for Bilaterally Ankylosed Hips Yong Lae Kim, MD,* Sang Ik Shin, MD,* Kwang Woo Nam, MD,* Jeong Joon Yoo, MD,* Young-Min Kim, MD,y and Hee Joong Kim, MD*z
Abstract: The purpose of this study was to evaluate the results of bilateral total hip arthroplasties (THAs) with special regard to angle of cup position in patients with bilaterally ankylosed hips. Twenty-four ankylosed hips were converted to THAs in 12 patients. Their mean age was 36 years and they were followed up for more than 3 years (average, 11 years). The mean Harris hip score increased from 55.4 to 82.3 points. Osteolysis and loosening were found in 3 and 2 hips, respectively. Eleven cups of 24 hips (46%) were outside the safe ranges of Lewinnek. Overall outcome after bilateral conversion of bilaterally ankylosed hips to THA was favorable, but the fused position of the contralateral limb had the tendency to define the direction of the malposition of the acetabular cup. Key words: bilaterally ankylosed hips, THA, acetabular cup position. © 2007 Elsevier Inc. All rights reserved.
performing THA, especially in the lateral position. If the contralateral limb is fixed in the abducted position, the pelvis will tilt cephalad in the coronal plane, and if the contralateral limb is fixed in the adducted position, it will tilt caudal. Moreover, fixed flexion contracture of the contralateral hip can also hinder proper pelvis positioning, and loss of spine motion in patients with ankylosing spondylitis can add to this problem. Improper positioning of the pelvis during the operation increases the likelihood of implant malpositioning, especially in the acetabular side. In the present retrospective study, clinical and radiographic outcomes of bilateral THA performed for bilateral ankylosis of the hip were evaluated with particular attention to acetabular cup positioning.
Ankylosis of the hip can cause neighboring joint pain such as low back pain and knee pain. For these reasons, conversion of hip ankylosis to total hip arthroplasty (THA) has been performed [1-4]. The results and the benefits of this conversion have been reported since the 1970s [1], but the procedure has been described as technically difficult [1,2,4,5]. Bone deformation, atrophy and contracture of surrounding soft tissues, the effects of previous operation, and alterations of normal anatomy all increase the difficulty of this procedure. Additional difficulty is expected in conversion of bilaterally ankylosed hips to THA. Ankylosis of the contralateral hip can be an obstacle to proper positioning of the pelvis that is essential for
From the *Department of Orthopaedic Surgery, Seoul National University Hospital, Seoul, South Korea; yDepartment of Orthopaedic Surgery, Seoul National University Bundang Hospital, Seongnam, South Korea; and zMedical Research Center, Seoul National University, Seoul, South Korea. Submitted January 30, 2007; accepted March 28, 2007. No benefits or funds were received in support of the study. Reprint requests: Hee Joong Kim, MD, Department of Orthopaedic Surgery, Seoul National University Hospital, 28 Yongondong, Chongnogu, Seoul 110-744, South Korea. © 2007 Elsevier Inc. All rights reserved. 0883-5403/07/1906-0004$32.00/0 doi:10.1016/j.arth.2007.03.027
Materials and Methods From May 1989 to May 2001, 24 hips of 12 patients with bilateral ankylosis of the hip were converted to THA by a single surgeon at our institute. Ankylosis of the hip was defined by physical examination as a total loss of hip motion. Both bony and fibrous ankylosis cases were included. All 12 patients were men, and average
1037
1038 The Journal of Arthroplasty Vol. 22 No. 7 October 2007 age at time of conversion was 36 years (range, 19-60 years). Six patients had bilateral bony ankylosis and 2 patients bilateral fibrous ankylosis. Four patients had bony ankylosis on one side and fibrous ankylosis on the other side. The mean duration of ankylosis before conversion was 11 years (range, 120 years). Initial diagnosis was ankylosing spondylitis in 5 patients, sequela of hip joint infection at childhood in 5, juvenile rheumatoid arthritis in 1, and heterotopic ossification after brain injury in 1. Both hips of 1 patient and a unilateral hip of 2 patients underwent surgical arthrodesis. The remaining hips fused spontaneously. The indication for surgery was progressive disabling pain in the low back or knee, loss of function caused by immobility or malposition of both hips, severe limping and walking disability. All patients had 2 or 3 of these problems. Contraction of the abductor muscle was palpable in all hips in this study. Patients without functioning abductor muscle were not indicated for conversion of their hip arthrodesis to THA. One patient received bilateral THA in a single day. Other patients were operated on sequentially with a mean interval of 19 days (range, 12-26 years). Operations were carried out in the lateral position for all hips by using a standard transtrochanteric approach [1,4,5]. A cementless acetabular cup was used in all hips. A porous coated Omnifit acetabular cup (Osteonics, Allendale, NJ) was used in 8 hips, a hydroxyapatitecoated Omnifit acetabular cup (Osteonics) in 6, a hydroxyapatite-coated ABG cup (Howmedica International, Staines, UK) in 4, an Arthopor II (DePuy, Warsaw, Ind) in 2, an H-G II cup (Zimmer, Warsaw, Ind) in 2, and a Plasmacup (Aesculap, Tuttlingen, Germany) in 2. A cemented stem was used in 9 hips and a cementless stem in 15. For cemented stems, a cemented Omnifit femoral stem (Osteonics) was used in 7 hips and an Exeter stem (Howmedica, Benoist-Girard, France) in 2. For cementless stems, a porous coated Omnifit femoral stem (Osteonics) was used in 3 hips, a hydroxyapatite-coated Omnifit femoral stem (Osteonics) in 4, a hydroxyapatite-coated S-Rom stem (DePuy) in 2, a hydroxyapatite-coated ABG stem (Howmedica International, Staines, UK) in 2, an H-G Multilock stem (Zimmer) in 2, and a BiContact stem (Aesculap) in 2. Metal-polyethylene articulation was used in 18 hips, zirconia-polyethylene in 2, alumina-polyethylene in 2, and contemporary alumina-alumina in 2. Patients were usually allowed to walk with support after 5 days, and full weight bearing was permitted after 10 weeks. No prophylactic anti-inflammatory drugs were used to prevent heterotopic
ossification. However, prophylactic radiation was performed in 1 patient with ankylosing spondylitis. The average follow-up period was 11 years (range, 3-17 years). Clinical and radiographic evaluations were performed at 6 weeks, 3 months, 6 months, and 1 year, and subsequently, annually or biannually. Clinical results were evaluated by calculating Harris hip scores [6]. Anterior-posterior (AP) and translateral hip radiographs were taken at every visit. Serial radiographs were examined concerning osteolysis and loosening. Periprosthetic cystic or scalloped lesions with a diameter of more than 2 mm that had not been present on immediate postoperative radiographs were defined as periprosthetic osteolysis [7,8]. Loosening of the acetabular cup was defined as a change in cup position exceeding 2 mm, a change in cup angle exceeding 3°, or the detection of a radiolucent line of thickness exceeding 2 mm around a cup. Cemented stem loosening was defined according to the criteria of Harris et al [9], whereas cementless stem loosening was defined as described by Engh et al [10]. Heterotopic ossification was classified using criteria of Brooker et al [11]. Acetabular cup inclinations were measured directly on AP radiographs. First, a horizontal line connecting both teardrops was drawn, and then a line was drawn through the longest diameter of the elliptical opening of the acetabular cup rim. The angle between these 2 lines was recorded as cup inclination. In cases with a poor teardrop outline or an asymmetric pelvis, a vertical line was drawn bisecting the sacrum and a line perpendicular to this line was used as reference horizontal line for measurement purposes. The method proposed by Pradhan [12] was used to calculate acetabular cup anteversion in AP radiographs. Acetabular cup inclination and anteversion were classified as to whether they were in or out of the safe range (40° ± 10° for inclination and 15° ± 10° for anteversion) proposed by Lewinnek et al [13].
Results Average Harris hip score increased from 55.4 points (range, 42-79 points) preoperatively to 82.3 points (range, 69-92 points) at final follow-up. Ten patients were able to walk without support at final follow-up. Seven patients had preoperative low back pain. Three of these patients had no back pain postoperatively, and the other 4 had residual low back pain that was more tolerable than preoperative pain. In 8 patients with preoperative knee pain, 6 showed improvement. One patient
Total Hip Arthroplasty for Bilaterally Ankylosed Hips Kim et al
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Table 1. Initial Position of the Limb and the Position of the Acetabular Cup
Patient Number 1 2 3 4 5 6 7 8 9 10 11 12
Inclination of the Cup *
Initial Position of the Limb Diagnosis Infection sequelae Juvenile rheumatoid arthritis Infection sequelae Infection sequelae Infection sequelae Ankylosing spondylitis Ankylosing spondylitis Heterotopic ossification Infection sequelae Ankylosing spondylitis Ankylosing spondylitis Ankylosing spondylitis
Right
Left
Right
Left
Anteversion of the Cup* Right
Left
Abduction 10° Flexion 60° Adduction 10° Flexion 10°
Adduction 20° Adduction 5°
Flexion 45° Flexion 10°
46.4° 43.9°
40° 47.1°
0° y 19.7°
Adduction 10° Adduction 35° Adduction 20° Abduction 40° Adduction 10° Abduction 10° Abduction 15° Adduction 10° Abduction 15° Adduction 10°
Neutral flexion Abduction 30° Abduction 10° Adduction 15° Abduction 5° Abduction 10° Adduction 5° Abduction 10° Adduction 5° Adduction 5°
Neutral flexion Flexion 40° Flexion 60° Flexion 60° Flexion 25° Flexion 30° Flexion 10° Flexion 20° Flexion 20° Flexion 25°
39.7° 28° y 47.4° 52.5° y 21° y 28.3° y 25.9° y 34.9° 46.7° 43.7°
47.1° 42.7° 54.5° y 49.9° 47.2° 36.8° 39° 44.1° 44.5° 46.2°
10.7° 7.3° 9.5° 0° y 19.9° 0° y 17.5° 35.5° y 21.4° 0° y 17.4° 9.1° 0° y 12.7° 28.5° y 7.3° 11.6° 6.7° 18.1° 20.6°
Neutral flexion Flexion 40° Flexion 70° Flexion 70° Flexion 15° Flexion 30° Flexion 15° Flexion 15° Flexion 30° Flexion 35°
16.7° 6.2°
*Average of the measurements of 3 observers. yOutside the safe zone.
with persistent knee pain received total knee arthroplasty and the other is waiting for this operation. All patients were subjectively satisfied with bilateral conversion of their arthrodesis to THA. Preoperative positions of fused hips are detailed in Table 1. Average flexion contracture at last followup was 4.6° (range, 0°-25°) and average further flexion was 76.3° (range, 45°-100°). Average hip range of motion in adduction was 10.3° (range, 5°20°) and in abduction was 39° (range, 15°-60°). Average limb length discrepancy after conversion was 0.6 cm (range, 0-1.5 cm). Overall inclinations and anteversions of acetabular cups are shown in Table 1. Six (25%) of the 24 hips were outside the Lewinnek acetabular cup inclination safe range, and 7 (29%) of the 24 hips were outside the Lewinnek acetabular cup anteversion safe range. Four cups had an inclination of less than 30° and 2 had an inclination of more than 50°. Of the 4 cups with an inclination of less than 30°, 3 had abduction contracture (average, 15°) of the contralateral limb. Two hips with cup inclination of more than 50° had adduction contracture (average, 17.5°) of the contralateral limb. Five cups showed zero anteversion. These hips had flexion and adduction contracture of the contralateral limb with an average flexion contracture of 36° and an average adduction contracture of 18°. Two cups with anteversion of more than 25° had flexion and abduction contracture of the contralateral limb with an average flexion contracture of 45° and an average abduction contracture of 25°. Overall cup malposition, whether in anteversion or inclination, was observed in 11 (46%) of the 24 hips. Of 10 hips with ankylosing spondylitis, 5 had a malpositioned cup, and of 14 hips with non-ankylosing spondylitis,
6 had a malpositioned cup. No difference was observed between these 2 groups in cup malposition frequency (χ2 test, P = .729). Osteolysis due to polyethylene wear was found in 3 hips. One patient with bilateral osteolysis at the acetabular and femoral sides underwent polyethylene liner exchange with bone grafting of the osteolytic lesions bilaterally. The left hip was operated on 15 years and 6 months and the right side was operated on 16 years and 2 months after index operations. One patient had progressive osteolysis at the acetabular side in the left hip without cup loosening and is awaiting revision. Radiographic evidence of cup loosening was detected in 1 patient bilaterally. The left side was symptomatic and was revised 11 years after the index operation. The right side was under close observation because it was asymptomatic and no cup positional change was detected. No stem was found loose at final follow-up in any patient. A femoral fracture occurred in 3 hips during stem implantation, and circumferential wiring was required. All of these intraoperative fractures healed without problem. Heterotopic ossification developed in 2 hips but, both was Brooker type I. Transient femoral nerve palsy was detected in 1 hip but this recovered spontaneously after 3 months. Peroneal nerve palsy with incomplete recovery also developed in 1 hip. There was neither postoperative dislocation nor trochanteric nonunion.
Discussion Arthrodesis used to be a good treatment option for various hip diseases, but it is known that longstanding ankylosis of the hip can result in low back
1040 The Journal of Arthroplasty Vol. 22 No. 7 October 2007 knowledge, no report has focused specifically on the bilateral conversion of bilateral ankylosed hips. In the present study, the overall clinical result was considered good as reflected by a final average Harris hip score of 82.3 points. Reoperation, including total implant revision, was performed in 3 of 24 hips. Relief of low back pain and knee pain was evident in most patients. Final ranges of motion were less satisfactory than those achieved by THA overall, and most patients had limping because of abductor weakness, but patient subjective satisfactions were excellent. A few complications were observed, but most were minor in nature. Many authors emphasize the technically demanding nature of the conversion procedure for ankylosed hips [1,2,4,5]. In cases of bilateral hip ankylosis, there is an additional problem because proper positioning of the pelvis during surgery is hindered by the contralateral limb. This problem may be a lesser concern for the second operated side,
Fig. 1. Direction of the malposition of the cup can be affected by the position of the contralateral limb. (A) If the contralateral limb is fixed in the abducted position, the pelvis will tilt cephalad. When the cup is inserted with an inclination of 40° referenced to the ground level, it creates the possibility of inserting the cup with less inclination than desired. (B) If the contralateral limb is fixed in the adducted position, the opposite can happen.
pain, knee pain, and contralateral hip pain. In particular, in cases with malpositioned fusion, pain related to degenerative changes in neighboring joints develops rapidly [14]. A number of studies have reported that THA is a good solution in this situation. Despite a number of complications encountered during earlier studies, midterm results have been encouraging regarding relief from neighboring joint pain [1,3-5], and patient subjective satisfaction appears to be excellent [2,15]. Although some long-term results have been somewhat less satisfactory [2,3,15], 2 recent reports presented encouraging long-term follow-up results [4,5]. To the best of our
Fig. 2. Plain AP radiograph of a 30-year-old male patient with ankylosing spondylitis. (A) The right limb is fixed at 40° abduction and 70° flexion. The left limb is fixed at 15° adduction and 60° flexion. (B) The right acetabular cup was inserted with an inclination of 52.5°. The left acetabular cup shows large elliptical opening. Calculated anteversion of the cup was 35.5°.
Total Hip Arthroplasty for Bilaterally Ankylosed Hips Kim et al
but because ranges of motion do not recover dramatically after conversion, the contralateral limb still effects positioning even after conversion. Kilgus et al [2] found that long-standing restriction of motion exists in a direction opposite to that of malposition after conversion. One patient received bilateral conversion in 1 day and the others received sequential conversion with an average interval of only 19 days in this study; thus, all the hips encountered this problem. In this study, the rate of malposition of the acetabular cup was 46% according to the safe range defined by Lewinnek. The direction of the malpositioning showed a tendency to be defined by the fixed position of the contralateral limb (Figs. 1 and 2). For example, fixed abduction of the contralateral limb was observed in 3 of 4 cups with an inclination less than 30°, and fixed adduction of the contralateral limb was observed in 2 cups with an inclination greater than 50°. If abduction or adduction of the contralateral limb is combined with fixed flexion contracture, the pelvis will tilt in the axial plain. Fixed adduction and flexion tilts the pelvis anteriorward and creates the possibility of inserting the cup with less anteversion than desired. Fixed abduction and flexion presents the opposite possibility, ie, of inserting the cup with more anteversion than desired. In the present study, 5 cups with zero anteversion had a contralateral limb fixed in adduction and flexion; 2 cups with anteversion of more than 25° had a contralateral limb fixed in abduction and flexion; and 1 cup with an inclination of less than 30° had the contralateral limb fixed in adduction. Even in unilaterally ankylosed hips, inserting an acetabular cup in a good position is difficult. Because of the pelvic deformity caused by the underlying disease and the secondary change in lumbar spine, anatomic landmarks cannot be used accurately. No intraoperative radiographs were taken in our series, but they may have been useful. In the future, computer-assisted surgery might solve this problem. Malpositioning of an acetabular cup increases the risk of postoperative dislocation. In the present study, there was no postoperative dislocation even in the cases in which the acetabular cup was inserted out of the safe range. Malpositioned components seemed to be well tolerated in these cases because of the greater trochanter repositioning and the limited range of motion after THA. There was no evidence that a malpositioned cup increased the polyethylene wear, osteolysis, or implant loosening. In conclusion, in this study, overall outcomes after bilateral conversion of bilateral hips with ankylosis to THA were found to be favorable, and patients were highly satisfied with the procedure. However,
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malposition of the contralateral limb may cause an additional difficulty in the conversion procedure that is naturally difficult.
References 1. Amstutz HC, Sakai DN. Total joint replacement for ankylosed hips: indications, technique, and preliminary results. J Bone Joint Surg [Am] 1975;57:619. 2. Kilgus DJ, Amstutz HC, Wolgin MA, et al. Joint replacement for ankylosed hips. J Bone Joint Surg [Am] 1990;72:45. 3. Strathy GM, Fitzgerald RH. Total hip arthroplasty in the ankylosed hip. A ten-year follow-up. J Bone Joint Surg [Am] 1988;70:963. 4. Kim YH, Oh SH, Kim JS, et al. Total hip arthroplasty for the treatment of osseous ankylosed hips. Clin Orthop 2003;414:136. 5. Hamadouche M, Kerboull L, Meunier A, et al. Total hip arthroplasty for the treatment of ankylosed hips: a five to twenty-one-year follow-up study. J Bone Joint Surg [Am] 2001;83:992. 6. Harris WH. Traumatic arthritis of the hip after dislocation and acetabular fractures: treatment by mold arthroplasty. An end-result using a new method of result evaluation. J Bone Joint Surg [Am] 1969;51:737. 7. Joshi RP, Eftekhar NS, McMahon DJ, et al. Osteolysis after Charnley primary low-friction arthroplasty. A comparison of two matched paired groups. J Bone Joint Surg [Br] 1998;80:585. 8. Maloney WJ, Jasty M, Harris WH, et al. Endosteal erosion in association with stable uncemented femoral components. J Bone Joint Surg [Am] 1990;72:1025. 9. Harris WH, McGann JC, O'Neil DA. Loosening of the femoral component after use of the medullary plug cementing technique. J Bone Joint Surg [Am] 1982;49:1063. 10. Engh CA, Massin P, Suthers KE. Roentgenographic assessment of the biologic fixation of porous-surfaced femoral components. Clin Orthop 1990; 257:107. 11. Brooker AF, Bowerman JW, Robinson RA, et al. Ectopic ossification following total hip replacement. Incidence and a method of classification. J Bone Joint Surg [Am] 1973;55:1629. 12. Pradhan R. Planar anteversion of the acetabular cup as determined from plain anteroposterior radiographs. J Bone Joint Surg [Br] 1999;81:431. 13. Lewinnek GE, Lewis JL, Tarr R. Dislocations after total hip replacement arthroplasties. J Bone Joint Surg [Am] 1978;60:217. 14. Gore DR, Murray MP. Walking patterns of men with unilateral surgical hip fusion. J Bone Joint Surg [Am] 1975;57:759. 15. Reikeras O, Bjerkreim I, Gundersson R. Total hip arthroplasty for arthrodesed hips. 5- to 13-year results. J Arthroplasty 1995;10:529.
Total Hip Arthroplasty for Bilaterally Ankylosed Hips Yong Lae Kim, MD,* Sang Ik Shin, MD,* Kwang Woo Nam, MD,* Jeong Joon Yoo, MD,* Young-Min Kim, MD,y and Hee Joong Kim, MD*z
Abstract: The purpose of this study was to evaluate the results of bilateral total hip arthroplasties (THAs) with special regard to angle of cup position in patients with bilaterally ankylosed hips. Twenty-four ankylosed hips were converted to THAs in 12 patients. Their mean age was 36 years and they were followed up for more than 3 years (average, 11 years). The mean Harris hip score increased from 55.4 to 82.3 points. Osteolysis and loosening were found in 3 and 2 hips, respectively. Eleven cups of 24 hips (46%) were outside the safe ranges of Lewinnek. Overall outcome after bilateral conversion of bilaterally ankylosed hips to THA was favorable, but the fused position of the contralateral limb had the tendency to define the direction of the malposition of the acetabular cup. Key words: bilaterally ankylosed hips, THA, acetabular cup position. © 2007 Elsevier Inc. All rights reserved.
performing THA, especially in the lateral position. If the contralateral limb is fixed in the abducted position, the pelvis will tilt cephalad in the coronal plane, and if the contralateral limb is fixed in the adducted position, it will tilt caudal. Moreover, fixed flexion contracture of the contralateral hip can also hinder proper pelvis positioning, and loss of spine motion in patients with ankylosing spondylitis can add to this problem. Improper positioning of the pelvis during the operation increases the likelihood of implant malpositioning, especially in the acetabular side. In the present retrospective study, clinical and radiographic outcomes of bilateral THA performed for bilateral ankylosis of the hip were evaluated with particular attention to acetabular cup positioning.
Ankylosis of the hip can cause neighboring joint pain such as low back pain and knee pain. For these reasons, conversion of hip ankylosis to total hip arthroplasty (THA) has been performed [1-4]. The results and the benefits of this conversion have been reported since the 1970s [1], but the procedure has been described as technically difficult [1,2,4,5]. Bone deformation, atrophy and contracture of surrounding soft tissues, the effects of previous operation, and alterations of normal anatomy all increase the difficulty of this procedure. Additional difficulty is expected in conversion of bilaterally ankylosed hips to THA. Ankylosis of the contralateral hip can be an obstacle to proper positioning of the pelvis that is essential for
From the *Department of Orthopaedic Surgery, Seoul National University Hospital, Seoul, South Korea; yDepartment of Orthopaedic Surgery, Seoul National University Bundang Hospital, Seongnam, South Korea; and zMedical Research Center, Seoul National University, Seoul, South Korea. Submitted January 30, 2007; accepted March 28, 2007. No benefits or funds were received in support of the study. Reprint requests: Hee Joong Kim, MD, Department of Orthopaedic Surgery, Seoul National University Hospital, 28 Yongondong, Chongnogu, Seoul 110-744, South Korea. © 2007 Elsevier Inc. All rights reserved. 0883-5403/07/1906-0004$32.00/0 doi:10.1016/j.arth.2007.03.027
Materials and Methods From May 1989 to May 2001, 24 hips of 12 patients with bilateral ankylosis of the hip were converted to THA by a single surgeon at our institute. Ankylosis of the hip was defined by physical examination as a total loss of hip motion. Both bony and fibrous ankylosis cases were included. All 12 patients were men, and average
1037
1038 The Journal of Arthroplasty Vol. 22 No. 7 October 2007 age at time of conversion was 36 years (range, 19-60 years). Six patients had bilateral bony ankylosis and 2 patients bilateral fibrous ankylosis. Four patients had bony ankylosis on one side and fibrous ankylosis on the other side. The mean duration of ankylosis before conversion was 11 years (range, 120 years). Initial diagnosis was ankylosing spondylitis in 5 patients, sequela of hip joint infection at childhood in 5, juvenile rheumatoid arthritis in 1, and heterotopic ossification after brain injury in 1. Both hips of 1 patient and a unilateral hip of 2 patients underwent surgical arthrodesis. The remaining hips fused spontaneously. The indication for surgery was progressive disabling pain in the low back or knee, loss of function caused by immobility or malposition of both hips, severe limping and walking disability. All patients had 2 or 3 of these problems. Contraction of the abductor muscle was palpable in all hips in this study. Patients without functioning abductor muscle were not indicated for conversion of their hip arthrodesis to THA. One patient received bilateral THA in a single day. Other patients were operated on sequentially with a mean interval of 19 days (range, 12-26 years). Operations were carried out in the lateral position for all hips by using a standard transtrochanteric approach [1,4,5]. A cementless acetabular cup was used in all hips. A porous coated Omnifit acetabular cup (Osteonics, Allendale, NJ) was used in 8 hips, a hydroxyapatitecoated Omnifit acetabular cup (Osteonics) in 6, a hydroxyapatite-coated ABG cup (Howmedica International, Staines, UK) in 4, an Arthopor II (DePuy, Warsaw, Ind) in 2, an H-G II cup (Zimmer, Warsaw, Ind) in 2, and a Plasmacup (Aesculap, Tuttlingen, Germany) in 2. A cemented stem was used in 9 hips and a cementless stem in 15. For cemented stems, a cemented Omnifit femoral stem (Osteonics) was used in 7 hips and an Exeter stem (Howmedica, Benoist-Girard, France) in 2. For cementless stems, a porous coated Omnifit femoral stem (Osteonics) was used in 3 hips, a hydroxyapatite-coated Omnifit femoral stem (Osteonics) in 4, a hydroxyapatite-coated S-Rom stem (DePuy) in 2, a hydroxyapatite-coated ABG stem (Howmedica International, Staines, UK) in 2, an H-G Multilock stem (Zimmer) in 2, and a BiContact stem (Aesculap) in 2. Metal-polyethylene articulation was used in 18 hips, zirconia-polyethylene in 2, alumina-polyethylene in 2, and contemporary alumina-alumina in 2. Patients were usually allowed to walk with support after 5 days, and full weight bearing was permitted after 10 weeks. No prophylactic anti-inflammatory drugs were used to prevent heterotopic
ossification. However, prophylactic radiation was performed in 1 patient with ankylosing spondylitis. The average follow-up period was 11 years (range, 3-17 years). Clinical and radiographic evaluations were performed at 6 weeks, 3 months, 6 months, and 1 year, and subsequently, annually or biannually. Clinical results were evaluated by calculating Harris hip scores [6]. Anterior-posterior (AP) and translateral hip radiographs were taken at every visit. Serial radiographs were examined concerning osteolysis and loosening. Periprosthetic cystic or scalloped lesions with a diameter of more than 2 mm that had not been present on immediate postoperative radiographs were defined as periprosthetic osteolysis [7,8]. Loosening of the acetabular cup was defined as a change in cup position exceeding 2 mm, a change in cup angle exceeding 3°, or the detection of a radiolucent line of thickness exceeding 2 mm around a cup. Cemented stem loosening was defined according to the criteria of Harris et al [9], whereas cementless stem loosening was defined as described by Engh et al [10]. Heterotopic ossification was classified using criteria of Brooker et al [11]. Acetabular cup inclinations were measured directly on AP radiographs. First, a horizontal line connecting both teardrops was drawn, and then a line was drawn through the longest diameter of the elliptical opening of the acetabular cup rim. The angle between these 2 lines was recorded as cup inclination. In cases with a poor teardrop outline or an asymmetric pelvis, a vertical line was drawn bisecting the sacrum and a line perpendicular to this line was used as reference horizontal line for measurement purposes. The method proposed by Pradhan [12] was used to calculate acetabular cup anteversion in AP radiographs. Acetabular cup inclination and anteversion were classified as to whether they were in or out of the safe range (40° ± 10° for inclination and 15° ± 10° for anteversion) proposed by Lewinnek et al [13].
Results Average Harris hip score increased from 55.4 points (range, 42-79 points) preoperatively to 82.3 points (range, 69-92 points) at final follow-up. Ten patients were able to walk without support at final follow-up. Seven patients had preoperative low back pain. Three of these patients had no back pain postoperatively, and the other 4 had residual low back pain that was more tolerable than preoperative pain. In 8 patients with preoperative knee pain, 6 showed improvement. One patient
Total Hip Arthroplasty for Bilaterally Ankylosed Hips Kim et al
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Table 1. Initial Position of the Limb and the Position of the Acetabular Cup
Patient Number 1 2 3 4 5 6 7 8 9 10 11 12
Inclination of the Cup *
Initial Position of the Limb Diagnosis Infection sequelae Juvenile rheumatoid arthritis Infection sequelae Infection sequelae Infection sequelae Ankylosing spondylitis Ankylosing spondylitis Heterotopic ossification Infection sequelae Ankylosing spondylitis Ankylosing spondylitis Ankylosing spondylitis
Right
Left
Right
Left
Anteversion of the Cup* Right
Left
Abduction 10° Flexion 60° Adduction 10° Flexion 10°
Adduction 20° Adduction 5°
Flexion 45° Flexion 10°
46.4° 43.9°
40° 47.1°
0° y 19.7°
Adduction 10° Adduction 35° Adduction 20° Abduction 40° Adduction 10° Abduction 10° Abduction 15° Adduction 10° Abduction 15° Adduction 10°
Neutral flexion Abduction 30° Abduction 10° Adduction 15° Abduction 5° Abduction 10° Adduction 5° Abduction 10° Adduction 5° Adduction 5°
Neutral flexion Flexion 40° Flexion 60° Flexion 60° Flexion 25° Flexion 30° Flexion 10° Flexion 20° Flexion 20° Flexion 25°
39.7° 28° y 47.4° 52.5° y 21° y 28.3° y 25.9° y 34.9° 46.7° 43.7°
47.1° 42.7° 54.5° y 49.9° 47.2° 36.8° 39° 44.1° 44.5° 46.2°
10.7° 7.3° 9.5° 0° y 19.9° 0° y 17.5° 35.5° y 21.4° 0° y 17.4° 9.1° 0° y 12.7° 28.5° y 7.3° 11.6° 6.7° 18.1° 20.6°
Neutral flexion Flexion 40° Flexion 70° Flexion 70° Flexion 15° Flexion 30° Flexion 15° Flexion 15° Flexion 30° Flexion 35°
16.7° 6.2°
*Average of the measurements of 3 observers. yOutside the safe zone.
with persistent knee pain received total knee arthroplasty and the other is waiting for this operation. All patients were subjectively satisfied with bilateral conversion of their arthrodesis to THA. Preoperative positions of fused hips are detailed in Table 1. Average flexion contracture at last followup was 4.6° (range, 0°-25°) and average further flexion was 76.3° (range, 45°-100°). Average hip range of motion in adduction was 10.3° (range, 5°20°) and in abduction was 39° (range, 15°-60°). Average limb length discrepancy after conversion was 0.6 cm (range, 0-1.5 cm). Overall inclinations and anteversions of acetabular cups are shown in Table 1. Six (25%) of the 24 hips were outside the Lewinnek acetabular cup inclination safe range, and 7 (29%) of the 24 hips were outside the Lewinnek acetabular cup anteversion safe range. Four cups had an inclination of less than 30° and 2 had an inclination of more than 50°. Of the 4 cups with an inclination of less than 30°, 3 had abduction contracture (average, 15°) of the contralateral limb. Two hips with cup inclination of more than 50° had adduction contracture (average, 17.5°) of the contralateral limb. Five cups showed zero anteversion. These hips had flexion and adduction contracture of the contralateral limb with an average flexion contracture of 36° and an average adduction contracture of 18°. Two cups with anteversion of more than 25° had flexion and abduction contracture of the contralateral limb with an average flexion contracture of 45° and an average abduction contracture of 25°. Overall cup malposition, whether in anteversion or inclination, was observed in 11 (46%) of the 24 hips. Of 10 hips with ankylosing spondylitis, 5 had a malpositioned cup, and of 14 hips with non-ankylosing spondylitis,
6 had a malpositioned cup. No difference was observed between these 2 groups in cup malposition frequency (χ2 test, P = .729). Osteolysis due to polyethylene wear was found in 3 hips. One patient with bilateral osteolysis at the acetabular and femoral sides underwent polyethylene liner exchange with bone grafting of the osteolytic lesions bilaterally. The left hip was operated on 15 years and 6 months and the right side was operated on 16 years and 2 months after index operations. One patient had progressive osteolysis at the acetabular side in the left hip without cup loosening and is awaiting revision. Radiographic evidence of cup loosening was detected in 1 patient bilaterally. The left side was symptomatic and was revised 11 years after the index operation. The right side was under close observation because it was asymptomatic and no cup positional change was detected. No stem was found loose at final follow-up in any patient. A femoral fracture occurred in 3 hips during stem implantation, and circumferential wiring was required. All of these intraoperative fractures healed without problem. Heterotopic ossification developed in 2 hips but, both was Brooker type I. Transient femoral nerve palsy was detected in 1 hip but this recovered spontaneously after 3 months. Peroneal nerve palsy with incomplete recovery also developed in 1 hip. There was neither postoperative dislocation nor trochanteric nonunion.
Discussion Arthrodesis used to be a good treatment option for various hip diseases, but it is known that longstanding ankylosis of the hip can result in low back
1040 The Journal of Arthroplasty Vol. 22 No. 7 October 2007 knowledge, no report has focused specifically on the bilateral conversion of bilateral ankylosed hips. In the present study, the overall clinical result was considered good as reflected by a final average Harris hip score of 82.3 points. Reoperation, including total implant revision, was performed in 3 of 24 hips. Relief of low back pain and knee pain was evident in most patients. Final ranges of motion were less satisfactory than those achieved by THA overall, and most patients had limping because of abductor weakness, but patient subjective satisfactions were excellent. A few complications were observed, but most were minor in nature. Many authors emphasize the technically demanding nature of the conversion procedure for ankylosed hips [1,2,4,5]. In cases of bilateral hip ankylosis, there is an additional problem because proper positioning of the pelvis during surgery is hindered by the contralateral limb. This problem may be a lesser concern for the second operated side,
Fig. 1. Direction of the malposition of the cup can be affected by the position of the contralateral limb. (A) If the contralateral limb is fixed in the abducted position, the pelvis will tilt cephalad. When the cup is inserted with an inclination of 40° referenced to the ground level, it creates the possibility of inserting the cup with less inclination than desired. (B) If the contralateral limb is fixed in the adducted position, the opposite can happen.
pain, knee pain, and contralateral hip pain. In particular, in cases with malpositioned fusion, pain related to degenerative changes in neighboring joints develops rapidly [14]. A number of studies have reported that THA is a good solution in this situation. Despite a number of complications encountered during earlier studies, midterm results have been encouraging regarding relief from neighboring joint pain [1,3-5], and patient subjective satisfaction appears to be excellent [2,15]. Although some long-term results have been somewhat less satisfactory [2,3,15], 2 recent reports presented encouraging long-term follow-up results [4,5]. To the best of our
Fig. 2. Plain AP radiograph of a 30-year-old male patient with ankylosing spondylitis. (A) The right limb is fixed at 40° abduction and 70° flexion. The left limb is fixed at 15° adduction and 60° flexion. (B) The right acetabular cup was inserted with an inclination of 52.5°. The left acetabular cup shows large elliptical opening. Calculated anteversion of the cup was 35.5°.
Total Hip Arthroplasty for Bilaterally Ankylosed Hips Kim et al
but because ranges of motion do not recover dramatically after conversion, the contralateral limb still effects positioning even after conversion. Kilgus et al [2] found that long-standing restriction of motion exists in a direction opposite to that of malposition after conversion. One patient received bilateral conversion in 1 day and the others received sequential conversion with an average interval of only 19 days in this study; thus, all the hips encountered this problem. In this study, the rate of malposition of the acetabular cup was 46% according to the safe range defined by Lewinnek. The direction of the malpositioning showed a tendency to be defined by the fixed position of the contralateral limb (Figs. 1 and 2). For example, fixed abduction of the contralateral limb was observed in 3 of 4 cups with an inclination less than 30°, and fixed adduction of the contralateral limb was observed in 2 cups with an inclination greater than 50°. If abduction or adduction of the contralateral limb is combined with fixed flexion contracture, the pelvis will tilt in the axial plain. Fixed adduction and flexion tilts the pelvis anteriorward and creates the possibility of inserting the cup with less anteversion than desired. Fixed abduction and flexion presents the opposite possibility, ie, of inserting the cup with more anteversion than desired. In the present study, 5 cups with zero anteversion had a contralateral limb fixed in adduction and flexion; 2 cups with anteversion of more than 25° had a contralateral limb fixed in abduction and flexion; and 1 cup with an inclination of less than 30° had the contralateral limb fixed in adduction. Even in unilaterally ankylosed hips, inserting an acetabular cup in a good position is difficult. Because of the pelvic deformity caused by the underlying disease and the secondary change in lumbar spine, anatomic landmarks cannot be used accurately. No intraoperative radiographs were taken in our series, but they may have been useful. In the future, computer-assisted surgery might solve this problem. Malpositioning of an acetabular cup increases the risk of postoperative dislocation. In the present study, there was no postoperative dislocation even in the cases in which the acetabular cup was inserted out of the safe range. Malpositioned components seemed to be well tolerated in these cases because of the greater trochanter repositioning and the limited range of motion after THA. There was no evidence that a malpositioned cup increased the polyethylene wear, osteolysis, or implant loosening. In conclusion, in this study, overall outcomes after bilateral conversion of bilateral hips with ankylosis to THA were found to be favorable, and patients were highly satisfied with the procedure. However,
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malposition of the contralateral limb may cause an additional difficulty in the conversion procedure that is naturally difficult.
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