Total Hip Arthroplasty After Previous Transtrochanteric Anterior

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Jeong Joon Yoo, MD, and Kyung-Hoi Koo, MD. Abstract: We compared the perioperative morbidity, position of the implants, implant stability, and clinical results ...
The Journal of Arthroplasty Vol. 24 No. 8 2009

Total Hip Arthroplasty After Previous Transtrochanteric Anterior Rotational Osteotomy for Femoral Head Osteonecrosis Young-Kyun Lee, MD, Yong-Chan Ha, MD, Ki-Choul Kim, MD, Jeong Joon Yoo, MD, and Kyung-Hoi Koo, MD

Abstract: We compared the perioperative morbidity, position of the implants, implant stability, and clinical results of 14 conversion total hip arthroplasties after previous transtrochanteric anterior rotational osteotomy with those of a matched control group of 28 primary total hip arthroplasties. The operation time was prolonged, perioperative blood loss increased, and the risk of stem or cup malposition was increased in the conversion group. However, there were no significant differences in the postoperative complications, clinical results, and implant stability between the 2 groups. None of the implants were loose in both groups. Transtrochanteric anterior rotational osteotomy should be advised, planned, and executed bearing in mind the operative morbidity and technically demanding nature of the conversion total hip arthroplasty. Keywords: hip, arthroplasty, transtrochanteric anterior rotational osteotomy, morbidity. © 2009 Elsevier Inc. All rights reserved.

Transtrochanteric anterior rotational osteotomy is a jointpreserving surgery for the treatment of femoral head osteonecrosis [1,1-5]. Previously reported success rates of this osteotomy ranged from 17% to 94% [1,1-8]. This means that conversion to total hip arthroplasty (THA) is necessary for some patients who have a previous transtrochanteric anterior rotational osteotomy. The anatomy of the proximal femur is distorted after the osteotomy, and subsequent THA can be technically demanding. To date, one study reported that transtrochanteric anterior rotational osteotomy did not influence the result of secondary THA [9]. However, the technical difficulties and perioperative morbidity of conversion THA after the osteotomy are not known. In the current study, we tried to determine whether previous transtrochanteric anterior rotational osteotomy affected the perioperative morbidity, the risk of implant malposition, and the outcome of conversion THA.

Materials and Methods Between December 1998 and December 2005, 14 osteonecrotic hips in 13 patients who had been treated From the Department of Orthopedic Surgery, Seoul National University College of Medicine Seoul, South Korea. Submitted January 14, 2009; accepted April 13, 2009. No benefits or funds were received in support of the study. Reprint requests: Yong-Chan Ha, MD, Department of Orthopaedic Surgery, Seoul National University Bundang Hospital, 166 Gumi-ro, Bundang-gu, Seongnam, Gyeonggi-do 463-707, South Korea. © 2009 Elsevier Inc. All rights reserved. 0883-5403/09/2408-0013$36.00/0 doi:10.1016/j.arth.2009.04.013

previously with transtrochanteric anterior rotational osteotomy were converted to THA by one surgeon because of secondary collapse of the femoral head after the osteotomy. The previous osteotomies had been performed by the same surgeon using a technique that has been described by Sugioka et al [1,5] except for skin incision and fixation device. Triradiate approach had been used instead of modified Ollier's approach. The osteotomy had been fixed using three or four 6.5-mm cancellous screws in 3 hips and a 120° compression hip screw (Solco, Seoul, South Korea) in 11 hips. There were 10 men (11 hips) and 3 women (3 hips), and the mean age at the time of osteotomy was 38.3 years (range, 23-49 years). Two hips were in stage IIB and 12 hips were in stage III according the modified Ficat staging system [10,11]. The causes of femoral head osteonecrosis were alcohol-induced in 4 hips, steroidinduced in 2 hips, posttraumatic in 1 hip, and idiopathic in 7 hips. The mean interval between the osteotomy and conversion THA was 1.7 years (range, 0.3-3.1 years). The mean age at the time of conversion THA was 40.0 years (range, 25- 51 years). The mean Harris hip score before conversion THA was 56.2 points (range, 41-72 points). Two designs of cementless implants were used: DELTA PF cup (LimaLto, Udine, Italy) with C2 stem (Lima-Lto) in 8 hips and PLASMACUP SC acetabular component (Aesculap, Tuttlingen, Germany) with BiCONTACT stem (Aesculap) in 6 hips. An alumina head and an alumina liner (BIOLOX

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1206 The Journal of Arthroplasty Vol. 24 No. 8 December 2009 forte, CeramTec AG, Plochingen, Germany) were used in all 14 hips. The diameter of the femoral head was 28 mm in 13 hips and 36 mm in 1 hip. All conversion THAs were carried out through the posterolateral approach. We removed previously inserted screws, plates, and wires. The hip joint was dislocated and the femoral neck was cut with an oscillating saw. After removal of the femoral head, the acetabulum was reamed. We tried to place the acetabular cup in 15° anteversion and 40° abduction. Normal anteversion of the femoral neck was distorted because the neck had been rotated anteriorly by 90° during previous osteotomy. Besides, endosteal sclerotic bone was formed in the proximal femur along the lag screw. Thus, we used gauge osteotome and/or burr to remove sclerotic bone in the proximal femur and to prepare the femoral canal. Special attention was made to remove sclerotic bone in the medial portion of the femoral neck and the lateral portion of subtrochanteric area to avoid varus or valgus positioning of stem. We tried to position the stem in 15° anteversion using the horizontal axis of the knee joint as a reference line instead of the axis of femoral neck at the cut surface. Cups and stems were inserted in a pressfit manner. Patients were instructed to walk with partial weight bearing with the aid of 2 crutches for 4 weeks after surgery. Follow-up evaluations were performed at 6 weeks; at 3, 6, 9, and 12 months; and every year thereafter. Patients who had not returned for regularly scheduled visits were contacted by telephone. Two nurses and one private locator found and visited nonresponders. These 13 patients (14 hips) were followed up for an average 4.8 years (range, 2- 9.6 years) after the conversion THA. Two control subjects were matched with each of the 14 hips for sex, age (1-year range), the initial diagnosis of osteonecrosis, cause of osteonecrosis, time of THA (1-year range), prosthesis design, and duration of follow-up (6month range) (Table 1). We compared the operation time, perioperative blood loss, requirement of transfusion, cup position, and stem alignment between the conversion THA group and

Table 1. Patient Demographic Data

Hips (patients) Male/female Age at THA (y) (mean ± SD) Etiology of osteonecrosis Alcohol Steroid Posttraumatic Idiopathic Follow-up period (y) (mean ± SD)

Conversion Group

Control Group

P

14 (13) 10:3 40.0 ± 8.8

28 (24) 18:6 40.1 ± 8.8

1.0 .979

4 2 1 7 4.8 ± 2.7

9 6 0 13 5.1 ± 2.7

.510

.639

control THA group. We also compared postoperative complications, Harris hip score [12], and radiologic results at the final follow-up. Abduction and anteversion angles of the acetabular components, alignments of the femoral stems, and leglength discrepancy were measured on 6-week anteroposterior radiographs. The abduction angle of the acetabular component was measured using the method described by Engh et al [13,14]. The anteversion of the acetabular component was calculated using the method of Widmer [15]. Cups with an abduction angle of ≤30° or ≥50° [16], or with an anteversion angle of ≤5° or ≥25° [17], were considered as outliers of optimal cup position. Stem alignment was determined by measuring the angle formed between the longitudinal axis of the femoral stem and the longitudinal axis of the femoral canal [18,19]. The alignment of the stem was classified as neutral, valgus (N5° of lateral deviation), or varus (N5° of medial deviation) [18,19]. To evaluate the leg-length discrepancy, we measured the distance between the interteardrop line and the lower margin of the lesser trochanter. The distances of the operated limb and the contralateral limb were compared [20], and the difference of more than 1.5 cm was defined as failure of leg-length equalization. The radiographic evaluation was done by 2 independent observers who did not participate in either osteotomy or THA. The 6-week anteroposterior and cross-table lateral radiographs were considered to be the baseline studies for radiographic comparison. The final radiographic evaluation included an assessment of the fixation of the acetabular and femoral components, ceramic liner wear, osteolysis, and heterotopic ossification. The fixation of the femoral component was classified with use of the method of Engh et al [21] and the fixation of the acetabular component with use of the method of Latimer and Lachiewicz [22]. The wear of ceramic liner was calculated according to the method developed by Livermore et al [23]. Osteolytic lesions were defined according the criteria of Engh et al [24]. The lesions were recorded according to the 3 zones described by DeLee and Charnley [25] on the acetabular side and the 7 zones described by Gruen et al [26] on the femoral side. Heterotopic ossification was classified according to the system of Brooker et al [27]. We used Fisher exact test for categorical variables and the Mann-Whitney U test for numerical variables. All reported P values were 2-sided, and P b .05 was used to determine statistical significance. All hips were assumed to be independent in the statistical analysis. For all statistical analyses, we used SPSS version 15.0 (SPSS, Chicago, Ill). The design and protocol of this retrospective study were approved by the institutional review board in our hospital, and all patients were informed that his or her

THA After Previous Transtrochanteric Anterior Rotational Osteotomy  Lee et al Table 2. Perioperative Morbidity Operating time (min) (mean ± SD) Perioperative blood loss (mL) (mean ± SD) Amount of transfusion (mL) (mean ± SD) Postoperative complication

Conversion Group

Control Group

190.0 ± 42.9

117.9 ± 19.6

b.001

P

1050.0 ± 249.5

724.7 ± 486.1

.003

831.4 ± 343.5

392.9 ± 291.7

b.001

1

0

.333

medical data could be used in a scientific study and provided consent preoperatively.

Results The operation time for THA was longer in the conversion group than in the control group (P b .001). Perioperative blood loss was greater in the conversion group than in the control group (P = .003). More amount of transfusion was required in the conversion group than in the control group (P b .001) (Table 2). Additional trochanteric osteotomy was required in 1 hip of conversion group to expose the acetabulum during conversion hip arthroplasty. We have failed to remove the broken screws, which had been use for the fixation of previous osteotomy, in one of the conversion group (Fig. 1A-D). Otherwise, no intraoperative complications occurred in both groups. The cup abduction angle and anteversion angle were significantly smaller in the conversion group than the control group (P = .008 and .016, respectively). The number of outliers was 6 in 14 conversion cups and 4 in 28 control cups (P = .059).

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Of 14 conversion stems, 5 were aligned in malposition (4 stems in varus and 1 stem in valgus position), whereas 2 of 28 control stems were aligned in varus position (P = .031) (Fig. 2A-C). One hip (7.1%) in conversion group and none in the control group had leg-length discrepancy of more than 1.5 cm (P = .333) (Table 3). Dislocation occurred in 1 converted hip due to a fall at postoperative 3 months after the conversion THA (P = .333), which was treated successfully with closed reduction and abduction bracing for 3 months (Fig. 1A-D). The mean Harris hip score was 93.7 points (range, 8298 points) in the conversion group and 95.3 points (range, 93-98 points) in the control group at the final follow-up (P = .592). All of the acetabular cups and femoral stems had radiographic evidence of bone ingrown stability at the time of the last follow-up. Periprosthetic osteolysis was not detected around any cup or stem. No ceramic wear was observed on the radiographs in all hips of the 2 groups. Brooker grade I or II heterotopic ossification developed in 2 conversion hips and 2 control hips (P = .590).

Discussion The reported success rates of trochanteric anterior rotational osteotomy were inconsistent ranging from 17% to 94% [1,1-8]. The secondary collapse after the osteotomy was the main cause of failure, and patients with failed osteotomy frequently need conversion THA. To date, 2 studies have evaluated the results of conversion THAs after transtrochanteric anterior rotational osteotomy or proximal femoral osteotomy [9,28]. Kawasaki et al [9] compared the results of 15 conversion THAs after failure of transtrochanteric

Fig. 1. (A) A 45-year-old man had been operated with transtrochanteric anterior rotational osteotomy for femoral head osteonecrosis. Anteroposterior radiograph at 30 months after the osteotomy shows a collapse of the femoral head. (B) He underwent a conversion THA. During the THA, additional trochanteric osteotomy was required to expose the acetabulum. Two screws, which had been use for the fixation of previous osteotomy, were broken during the operation and retained. (C) His hip was dislocated 3 months after the conversion THA. The greater trochanter was migrated proximally. (D) The dislocation was treated with closed reduction and abduction brace for 3 months. Anteroposterior radiograph at 36 months after the reduction.

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Fig. 2. (A) A 45-year-old man, who had been operated with transtrochanteric anterior rotational osteotomy for femoral head osteonecrosis, underwent a conversion THA. A 6-week anteroposterior radiograph shows a varus alignment of the stem. (B) A 33year-old man who had been operated with transtrochanteric anterior rotational osteotomy for femoral head osteonecrosis underwent a conversion THA. A 6-week anteroposterior radiograph shows a valgus alignment of the stem and suboptimally anteverted cup. (C) A 52-year-old man underwent a primary THA because of femoral head osteonecrosis. A 6-week anteroposterior radiograph shows an optimal cup position and neutral alignment of the stem.

rotational osteotomy with 16 matched control THAs. They used various designs of hip prosthesis and they compared the results of conversion THA with limited number of control group. Boos et al [28] compared 74 THAs after previous proximal femoral osteotomies in various disease, including primary osteoarthritis and developmental dislocation of the hip, with diagnosismatched 74 control THAs. In their study, the osteotomies were various; varus osteotomy in 33, valgus osteotomy in 15, and unidentified in 26. They used cemented stem and the mean age of their patients were 57.4 years (range, 34-79 years). In both studies of Kawasaki et al [9] and Boos et al [28], there were no significant differences in the result and survival between the conversion THAs and primary THAs, although the operating time was longer and perioperative blood loss was greater in the conversion group. However, possible differences of cup position and stem alignment between the conversion group and primary group were not evaluated in both studies of Kawasaki et al [9] and Boos et al [28]. Table 3. Cup Position and Stem Alignment Cup abduction (deg) (mean ± SD) Cup anteversion (deg) (mean ± SD) No. of outlier of cup position No. of stems in malposition No. of leg-length discrepancy

Conversion Group

Control Group

P

35.3 ± 6.2

40.2 ± 4.6

.008

13.9 ± 6.8

18.4 ± 4.0

.016

6

4

.059

5

2

.031

1

0

.333

In our study, all patients in conversion group had been operated previously with transtrochanteric anterior rotational osteotomy for femoral head osteonecrosis by single surgeon, and we used cementless prosthesis designs; slightly tapered, rectangular stems with proximal porous-coat and porous-coated cups. Our patients were younger (mean, 40.0 years) at the time of conversion THA compared to the patients in the study of Boos et al [28]. Our study showed that the risk of stem malposition was increased (P = .031), and the cup abduction angle and anteversion angle were smaller (P = .008 and .016, respectively) in the conversion group. The number of outliers also increased with a marginal significance (P = .592) in the conversion cups. During the osteotomy, the femoral head segment was rotated anteriorly by 90° and the mediolateral dimension of the intertrochanteric portion, which was greater than the anteroposterior dimension, was directed into the anteroposterior dimension. These rotational changes affected the anteversion of the femoral component and masked the landmark for stem insertion. The osteotomy distorted the neck-shaft angle into a varus alignment, which would have influenced the selection of stem design and size. Hard sclerotic bone was formed around the screws, which had been used for the fixation of osteotomy. The acetabular deformity due to osteophyte formation would have influenced the position of acetabular cup. There were several limitations in our study. Our study was a retrospective one performed in a small cohort with a short-term follow-up. Despite these limitations, our study showed possible problems during THA after previous transtrochanteric rotational osteotomy.

THA After Previous Transtrochanteric Anterior Rotational Osteotomy  Lee et al

We recommend that transtrochanteric rotational osteotomy be advised, planned, and executed bearing in mind the possible increase of morbidity and technical demand of subsequent THA. Careful preoperative evaluation of anatomy and preoperative planning are necessary for this technically demanding arthroplasty.

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