The posterolateral approach was used by the other three surgeons (EMK, PMF, JBM) in 190 hips on 181 patients. There were 82 (45.3%) men and 99 (54.7%) women. The average age was 67 years (range, 32–89 years). Osteoarthritis was the primary diagnosis in 169 (88.9%) patients (Table 1). A cemented, all-polyethylene acetabular component was used in 125 hips (65.8%) and a cemented femoral component was used in 152 hips (80%) (Table 2). Twenty-eight millimeter heads were used in each procedure and neck lengths were adjusted for appropriate soft tissue tension. The short external rotators and posterior capsule were not repaired in this series.
Patients were evaluated for limp and dislocation using the Harris hip score. 6 All patients who were seen in the clinic for a 1-year followup and all patients who could be contacted by telephone or letter were included in the study. Certain objective findings in the Harris hip score such as range of motion (ROM) and absence of deformity cannot be evaluated in a telephone interview; however, these scores constitute a minimal contribution to the total score. Patients with telephone interviews were questioned whether any change in their hips had occurred since the last clinic visit. As the patients stated that no changes had occurred, the patients’ scores from the most recent clinic visit were used in the ROM and absence of deformity categories.
Limp was not categorized as to type. All limp, as observed by the evaluator or perceived by the patient, was categorized as a positive response. Likewise, dislocations were not categorized as to etiology or recurrence. Any dislocation or dislocations were classified as one positive response for that patient.
Three other dependent variables also were compared between the groups and included length of stay, infection, and discharge disposition.
T tests were used to compare average hip scores and length of stay. A Wilcoxon rank sum test was used to compare average pain scores. Fisher’s exact test was used to compare gait scores and presence or absence of limp. Chi square tests were used to compare frequency of types of discharge disposition, and the frequency of dislocation.
Patients with 96 of the anterolateral approach to the hip and 190 of the posterior approach were evaluated in the clinic at the patients’ 1-year followup. Patients with 26 of the anterolateral approach to the hip and 38 with the posterior approach were evaluated by letter or telephone call. Eight patients with eight anterolateral total hip replacements either were deceased (four patients) or lost to followup (four patients). Three patients with three posterior total hip replacements were deceased and three patients with three posterior total hip replacements hips were lost to followup. Patients who were lost to followup were included in the length of hospital stay and disposition analysis, but were excluded from the remainder of the comparison. Average followup for the anterolateral approach was 14.8 months (range, 9.2–28.2 months), and for the posterior approach the average followup was 14.7 months (range, 10–29 months). Discharge data are provided in Table 3.
The average Harris hip score for the anterolateral approach was 92.63 ± 12.20 (range, 35–100 points) and the average pain score was 41.66 ± 6.07. For the posterior approach, the average Harris hip score was 92.03 ± 10.15 (range, 25–100 points), and the average pain score was 41.91 ± 4.98. Limp of any severity was seen in 35 (28.69%) of the patients with the anterolateral approach, nine (7.38%) of whom had a moderate or severe limp (Table 4). Limp of any severity was seen in 31 patients with the posterior approach (16.84%) and moderate or severe limp was seen in seven patients (3.8%) (Table 4).
Length of Stay and Discharge Disposition
The average length of stay for patients with the anterolateral approach was 5.25 days ± 11.39 (range, 3–14 days). The average length of hospital stay for patients with the posterior approach was 5.19 days ± 0.95 (range, 2–10 days). Eighty-one (62.31%) patients who had the anterolateral approach were discharged to home or self-care and seven (5.38%) were discharged to rehabilitation facilities (Table 3). One hundred thirty-two patients (69.47%) who had the posterior approach were discharged home or to self-care and 12 patients (6.32%) were transferred to rehabilitation facilities. One patient with the anterolateral approach and one patient with the posterior approach had an infection.
No patient with the anterolateral approach experienced dislocation. There were eight (4.21%) hips with the posterior approach in which dislocation occurred. Five of the dislocations were anterior and three were posterior.
Of the many factors that have been used to compare the anterolateral and posterolateral approaches to the hip (blood loss, time of operation, ectopic bone formation, length of stay, neurologic injury, limp, and dislocation), the most persistent differences are perceived to be postoperative limp and postoperative instability (dislocation). Articles by Roberts et al, 13 Turner, 14 Vicar and Coleman, 15 and Woo and Morrey, 16 have detailed a higher dislocation rate with the posterolateral approach as compared with the anterolateral approach as shown by Mallory et al 9 and Mulliken et al. 12
The current findings support these observations with eight dislocations occurring in patients in the posterolateral group as opposed to no dislocations in the anterolateral group (p = 0.018). McCollum and Gray 10 suggested that this increased dislocation rate might be attributable to inadequate acetabular exposure and consequent malposition of the acetabular component. Five of the eight dislocations in patients in the study were anterior. This suggests two possible etiologies, one being excessive anteversion of the acetabular component perhaps as overcompensation for the tendency to retrovert the component and for a weakened or absent posterior capsule or both. The second possible etiology is the desire to remove anterior impingement sources, leading to overly aggressive removal of anterior osteophytes and anterior capsule, resulting in secondary weakening of the anterior restraints to instability. In the anterolateral approach, the posterior capsule and osteophytes are left intact.
All four surgeons have many years experience with the approach of their choice. Acetabular exposure is thought to be adequate in both approaches and orientation of the acetabular component was done using standard landmarks; however, special radiographic techniques to measure anteversion were not done and consequently acetabular position is not compared in this study.
Postoperative limp has been cited as the biggest objection to the anterolateral approach. Hardinge 4 described a modification of the direct lateral approach to the hip reported by McFarland and Osborne. 11 This involved splitting the gluteus medius continuous with the anterior aspect of the vastus lateralis. Criticism of this approach included prolonged limp and partial denervation of the gluteus medius. 1,5 The anterolateral approach used in this study was a slight modification of that described by Mulliken et al 12 in which the gluteus medius split proceeded anteriorly from the superior tip of the greater trochanter, differing from that described by Hardinge. 4 With these modifications, limp seems to be less of a problem. The current study showed no significant difference in limp although there was a greater percentage of patients in the anterolateral group who limped (21.3% versus 13%). Greater patient numbers would be required to establish a statistical difference. No other significant differences were found between the two groups in Harris hip scores, length of hospital stay, or discharge disposition.
Based on the current study, there appears to be a trade off between the two approaches as related to dislocation versus limp. However, with the newer modifications of the anterolateral approach, it appears that postoperative limping is less of a problem and that the incidence of dislocations as a result of using the posterior approach remains high.
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© 2001 Lippincott Williams & Wilkins, Inc.
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