The anterior supine intermuscular approach for total hip arthroplasty (THA) continues to gain acceptance with surgeons and patients. By taking advantage of the internervous and intermuscular plane between the femoral nerve medially and the superior and inferior gluteal nerves laterally, the hip joint is exposed without detaching any muscles from the pelvis or femur.1–6 Improved gait symmetry at 6 weeks postoperatively, decreased dislocation rate, and leg-length restoration with decreased surgical trauma are some benefits of the anterior approach. Multiple single-surgeon series are promising but emphasize the moderate to high complication rate and lengthy learning curve.7–10 A recent report from a community hospital showed a high complication rate.11 One of the selling points of the anterior supine intermuscular approach is the early return to unrestricted physical activity with no hip precautions. However, its benefits may be counterbalanced by its complications.
The purpose of this study was to report the results and acute complications related to the anterior supine intermuscular approach for THA when the transition from other approaches was made in a teaching academic setting. The timing of complications relative to an apparent learning curve is described.
Materials and Methods
Between April 2009 and September 2010, sixty-one consecutive primary THAs were performed in 54 patients at a Level I academic trauma center using the anterior supine intermuscular approach on the OSI PROfx table (Mizuho OSI, Union City, California) as previously described.1–3 All procedures were performed by or while under the direct supervision of the senior author (S.J.M.). Before adopting the anterior supine intermuscular approach, the senior author attended a training session with an expert and direct observation of the procedure. Institutional review board approval was obtained prior to initiation of the study.
Prospectively collected data was retrospectively reviewed. Demographic information, intra- and postoperative complications, estimated blood loss, operative time, and length of stay were recorded.
During the study period, the anterior supine intermuscular approach was the preferred surgical approach used by the senior author for all primary THAs. Patients with significant acetabular bone loss, acetabular protrusio, acetabular tumors, posttraumatic deformity, severe dysplasia (Crowe III and IV),6 ankylosing spondylitis, and extensive heterotophic ossification requiring a THA were treated using a posterior approach. Patients who had previous hip surgery were excluded from the study.
Radiographic analysis was performed on pre-, intra-, immediate post-, and 6-week postoperative anteroposterior pelvic and lateral radiographs. Subsequent radiographs were obtained 6 months postoperatively and annually thereafter. Radiographic assessment was performed by an orthopedic surgeon (C.Y.) not involved in the surgeries. Measurements included cup abduction angle, cup anteversion angle, stem alignment, stem subsidence, and postoperative leg-length discrepancy. The cup abduction was measured as the angle between the teardrop line and the major diameter of the ellipse represented by the rim of the acetabular cup.2,12 The line of the anteversion angle was calculated as the length of the transverse width of the center of the acetabular ellipse divided by the length of the major diameter.2 Determination of leg length was done by measuring the vertical height from the inter-teardrop line (a horizontal line drawn along the lower edge of the right and left acetabular teardrop) to a point chosen on the center of the lesser trochanter considered a reproducible landmark on both sides.2,13 Malposition of the acetabular component was defined as a cup abduction angle of 30° or less or 50° or more. Varus or valgus malposition of the femoral stem was considered to be present when the longitudinal axis of the stem was tilted in more than 5° of varus or valgus relative to the diaphyseal axis of the femur.
All implants used were press-fit cementless acetabular components with or without screws (Pinnacle Acetabular Cup; DePuy, Warsaw, Indiana). The femoral components used were hydroxyapatite-coated cementless titanium alloy stems (Corail or Trilock femoral stem; DePuy). Patients routinely received low-molecular-weight heparin for 14 days postoperatively. All patients were fully weight bearing with the use of crutches or a walker postoperatively, except for patients with intraoperative fractures. In patients with femoral calcar fractures, weight bearing was restricted to 50% for 6 weeks. In cases with femoral trochanteric fractures, no active abduction was allowed for 6 weeks. Otherwise, no hip precautions or limitations were used. All patients received daily inpatient physical therapy treatment during their length of stay.
Clinical follow-up was performed at 2 and 6 weeks, 3 and 6 months, 1 year, and annually thereafter.
A total of 106 primary THAs were performed during the study period. The posterolateral approach was used in 45 hips performed by a different attending surgeon (M.K.D.). Sixty-one THAs were performed through an anterior supine intermuscular approach. The study group comprised 29 men and 25 women with a mean age at surgery of 55.6 years (range, 33–73 years). All patients completed the 6-month follow up (average, 13.1 months; range, 6–20 months). Demographic data are shown in Table 1. Thirty-one procedures involved the left hip, 30 involved the right hip, and 7 were bilateral staged procedures. In cases of bilateral surgeries, 3 months was the minimum time between surgeries. Mean body mass index was 28.3 kg/m2 (range, 17.6–44.2 kg/m2). Preoperative diagnoses included osteoarthritis in 43 hips, osteonecrosis in 11 hips, femoral neck fractures in 6 hips, and congenital hip dysplasia in 1 hip. Mean operative time was 110.4 minutes (range, 64–183 minutes), and average estimated blood loss was 378.69 mL (range, 100–1000 mL). Three (4.92%) patients received blood transfusion postoperatively. Mean hospital length of stay was 3.85 days (range, 2–13 days). The patient with a 13-day hospital stay had a history of chronic obstructive pulmonary disease and required intensive care unit admission postoperatively because of pneumonia secondary to aspiration.
Table 1: Demographic Data
Five (8.2%) intraoperative complications were observed, including 3 greater trochanter fractures and 2 calcar fractures. Two of 3 greater trochanteric fractures were treated with cable fixation during the initial surgery, and 1 nondisplaced greater trochanteric fracture was judged to be stable so no additional fixation was performed. The 2 calcar fractures occurred during broaching and were managed successfully with cable fixation during the same procedure, without additional extension of the original incision. Each of these patients had an uncomplicated recovery.
One patient had transient numbness in the thigh caused by lateral femoral cutaneous nerve damage, which had completely resolved at 6-week follow-up. No femoral nerve palsies occurred. Wound complications occurred in 2 patients. One wound hematoma and 1 superficial infection in a patient with diabetes mellitus with a history of recurrent cellulitis were successfully treated with irrigation and debridement and retention of the implants during the immediate postoperative period. No deep infections were noted.
One anterior hip dislocation occurred on postoperative day 5 during positioning for irrigation and debridement in the operating room. The size of the femoral head on this patient was 36 mm. Radiographic analysis show no malposition of the components. Closed reduction was successful, and at 1-year follow-up, the patient had not experienced recurrent dislocations.
Two (3.27%) patients required femoral component revision. One patient presented to 3-month follow-up reporting increasing thigh pain. On radiographic evaluation, the stem had subsided with symptomatic subluxation of the hip. The stem was revised 3 months after the index surgery through the posterior approach, with uneventful recovery (Figure). The second patient had continued thigh pain 7 months after the index procedure. Evidence of stem loosening with pedestal formation was present on radiographs. The patient initially refused revision, but opted for surgery 12 months after the index procedure. The stem was revised through the posterior approach. Two weeks postoperatively, the patient was pain free.
Figure: Anteroposterior pelvis radiograph of a 50-year-old woman immediately after undergoing uncomplicated left primary anterior supine intermuscular total hip arthroplasty (A). Anteroposterior pelvis radiograph taken 3 months postoperatively after complaints of continued thigh pain showing that the stem had subsided with symptomatic subluxation of the hip (B). Anteroposterior pelvis radiograph taken after the stem was revised using a posterior approach.
The overall complication rate was 16.4% (10/61). All complications occurred during the first 32 cases (31.25% early complication rate), and none occurred during the last 29 cases. The overall reoperation rate was 6.56% (4/61). No femoral or sciatic nerve injuries occurred, and no patient was diagnosed with venous thromboembolism. Complication data are shown in Table 2.
Table 2: Complications
Radiographic analyses are shown in Table 3. No complete radiolucent lines were noted around any acetabular components. Average acetabular cup abduction angle was 43.79°±6.37° (range, 30.44°–58.17°). Abduction angles in 6 hips exceeded 50°. The incidence of cup malposition, defined as cups with an abduction angle of 30° or less or 50° or more, was 9.84% despite the use of fluoroscopy in all cases. Average anteversion was 20.61°±2.57° (range, 12.51°–24.68°). All cases were within the target range of 10° to 25°. One stem was placed in 6° of varus and 1 stem in 7° of valgus relative to the diaphyseal axis of the femur (3.28%). Average postoperative leg-length discrepancy was 2.24±3.22 mm (range, 0–17.1 mm) as measured on intra-operative radiographs.
Table 3: Radiographic Analysis
The aim of this study was to evaluate the early complications of using the anterior supine intermuscular approach for THA in an academic setting. In the authors’ early experience with the anterior supine intermuscular approach for THA using a fracture table, a relatively high rate of complications (16.4%) and reoperations (6.5%) occurred at a minimum 6-month follow-up, which is consistent with other recent reports.9,11,14
Woolson et al11 reported an increased operative time (164 minutes), a high blood loss intraoperatively (858 mL), and an overall complication rate of 13% in 247 THAs performed at a community hospital by 5 orthopedic surgeons. Nine percent had a major complication, including 16 femoral shaft or trochanteric fractures, 2 deep infections, 2 peroneal nerve injuries, and 3 immediate reoperations for leg-length discrepancy. No postoperative dislocations occurred.11 In the current study, the incidence of fracture was higher (8.2%), intraoperative blood loss was lower (378.69 mL), and operative time was shorter (110.4 minutes).
In a comparative study of a minimally invasive anterior 2-incision surgical approach to THA, Bal et al9 reported an overall complication rate of 42% (37/89) and an overall reoperation rate of 10% (9/89). Sendtner et al14 compared the results of the anterior minimally invasive approach with those of the traditional lateral approach during the learning curve of a single surgeon. They reported decreased blood loss but similar clinical and radiographic outcomes and similar complication rates compared with standard THA. Their complication rate for the anterior supine intermuscular approach (18.9%; 14/74) was higher than for the lateral approach (11.7%; 7/60).
Other authors reported low complication rates.1,2,15 Siguier et al1 reported the results of 1037 THAs using the anterior supine intermuscular approach on an orthopedic table. Their dislocation rate was 0.96%. Additional complications included 2 femoral nerve palsies, 5 deep infections, and 1 ankle fracture.1 Matta et al2 reported a series of 494 primary THAs performed through an anterior approach on an orthopedic table. Seventeen (3.89%) complications occurred, including 1 deep infection, 3 wound infections, 1 transient femoral nerve palsy, 3 greater trochanteric fractures, 2 femoral shaft fractures, 4 calcar fractures, and 3 ankle fractures.2
Minimally invasive techniques for THA demonstrate a high rate of complications during the surgeon’s learning curve.16 Woolson et al8 suggested that the learning curve includes the first 20 cases for a single surgeon. Seng et al17 described a learning curve of approximately 40 cases. However, a previous multicenter study by the Anterior Total Hip Arthroplasty Collaborative (ATHAC) Investigators reported that surgeons with more than 100 hip cases reduced overall complication rates.18 Most complications in the current study occurred in the first 32 cases.
Intraoperative fractures of the proximal femur are the most frequent complications associated with minimally invasive techniques for THA.11,19 Jewett and Collis19 reported trochanteric fractures and femur perforations as the main complications seen relatively early in their 800 primary THAs; none were seen in the second half of the series. Nineteen (2.3%) trochanteric fractures and 15 (1.8%) trochanteric injuries occurred within the first 200 cases. Three (0.37%) femoral canal perforations occurred within the first 150 cases.19
Injury to branches of the lateral femoral cutaneous nerve is a recognized complication after anterior approach THA. The distal branches of the lateral femoral cutaneous nerve are at risk with distal extension of the incision. Seng et al17 reported only 2 (1.09%) cases of transient lateral femoral cutaneous nerve paresthesia in 182 patients after anterior THA, both of which resolved. The ATHAC investigators reported 13 neurological complications in 1152 direct anterior approach THAs.18 However, Goulding et al20 reported lateral femoral cutaneous nerve neuropraxia in 107 (81%) of 132 patients after anterior approach THA. They concluded that lateral femoral cutaneous nerve neuropraxia is underreported but does not lead to functional limitations.20 One lateral femoral cutaneous nerve injury was noted in the current study, which completely resolved by 6 weeks postoperatively. One possible explanation for this lower incidence of lateral femoral cutaneous nerve injuries is the more lateral placement of the incision approximately 6 to 8 cm lateral to a line projection from the anterior superior iliac spine to the lateral border of the patella. The authors believe that this variation helped avoid direct exposure and injury to the branches of the lateral femoral cutaneous nerve.
The occurrence of dislocation after THA continues to be a serious problem. Siguier et al1 reported a dislocation rate of 0.96% (10/1037 hips). Kennon et al4 reported a dislocation rate of 1.3%. In a multicenter study, the ATHAC Investigators reported a dislocation rate of 0.6% (8/1152, of which 3 [0.2%] required implant revision). In the current study, 1 (1.6%) dislocation occurred during a reintervention for irrigation and debridement of an infected hematoma 5 days after index surgery; at 1-year follow-up, the patient had no additional dislocations. One potential advantage of the anterior supine intermuscular THA is the preservation of the short external rotator tendons and posterior capsule compared with the posterior approach.21,22 Compared with the anterolateral modified Hardinge approach, the gluteus medius and minimus tendons are left undisturbed.
The surgical wound complication rate in the current study was similar to that in other studies. Two (3.28%) wound-related complications occurred in the current study: 1 infected hematoma and 1 sterile hematoma (negative cultures). Both were treated by irrigation and debridement. Jewett and Collis19 reported a 4.6% rate of serious wound-healing complications, with a 1.6% reoperation rate for wound infections and wound necrosis. The relatively high rate of wound complications and infections may be multifactorial. The current authors have observed skin maceration and superficial abrasion from retractor placement and broaching. Also, an increase in the number of assistants, C-arm technicians, and operating room personnel, as well as the placement of the fluoroscope right above the incision, may increase the surgical wound contamination rate.
This study had several limitations. Its retrospective nature with no control group may have introduced bias into the results. However, the goal was to describe early complications and the accuracy of implant placement using this approach as important determinants of long-term outcome in THA. Complete radiographic and clinical follow-up were conducted for all patients for a minimum of 6 months. Specific outcome measurements were not used, but the authors intended to describe intra- and early postoperative complications. The surgeries were performed in an academic setting with the participation of physician assistant providers, residents, and fellows with varying levels of training and surgical skills. This may have affected the complication rate.
The anterior supine intermuscular approach to THA may not be the optimal surgical approach to train junior staff or to use in low-volume practices. Most pioneers of the technique are expert orthopedic surgeons using the approach exclusively in large-volume practices who have been able to master the technique and decrease complications.
The anterior supine intermuscular THA using an orthopedic table requires dedicated additional training and careful attention to detail. A high initial incidence of complications should be disclosed to the patient when offering this approach during a surgeon’s early experience. The short-term potential benefits, although attractive to patients and surgeons, should be carefully evaluated against the potential complications when the procedure is performed by less experienced surgeons.
- Siguier T, Siguier M, Brumpt B. Mini-incision anterior approach does not increase dislocation rate: a study of 1037 total hip replacements. Clin Orthop Relat Res. 2004; (426):164–173 doi:10.1097/01.blo.0000136651.21191.9f [CrossRef] .
- Matta JM, Shahrdar C, Ferguson T. Single-incision anterior approach for total hip arthroplasty on an orthopaedic table. Clin Orthop Relat Res. 2005; (441):115–124 doi:10.1097/01.blo.0000194309.70518.cb [CrossRef] .
- Matta JM, Ferguson TA. The anterior approach for hip replacement. Orthopedics. 2005; 28(9):927–928.
- Kennon R, Keggi J, Zatorski LE, et al. Total hip arthroplasty through a minimally invasive anterior surgical approach. J Bone Joint Surg Am. 2003; 85(suppl 4):39–48.
- Kennon R, Keggi J, Zatorski LE, Keggi KJ. Anterior approach for total hip arthroplasty: beyond the minimally invasive technique. J Bone Joint Surg Am. 2004; 86(suppl 2):91–97.
- Nakata K, Nishikawa M, Yamamoto K, Hirota S, Yoshikawa H. A clinical comparative study of the direct anterior with mini-posterior approach. J Arthroplasty. 2009; 24(5):698–704 doi:10.1016/j.arth.2008.04.012 [CrossRef] .
- Berger RA. Total hip arthroplasty using the minimally invasive two-incision approach. Clin Orthop Relat Res. 2003; (417):232–241.
- Woolson ST, Mow CS, Syquia JF, Lannin JV, Schurman DJ. Comparison of primary total hip replacements performed with a standard incision or a mini-incision. J Bone Joint Surg Am. 2004; 86(7):1353–1358.
- Bal BS, Haltom D, Aleto T, Barrett M. Early complications of primary total hip replacement performed with a two-incision minimally invasive technique. J Bone Joint Surg Am. 2005; 87(11):2432–2438 doi:10.2106/JBJS.D.02847 [CrossRef] .
- D’Arrigo C, Speranza A, Monaco E, Carcangiu A, Ferretti A. Learning curve in tissue sparing total hip replacement: comparison between different approaches. J Orthop Traumatol. 2009; 10(1):47–54 doi:10.1007/s10195-008-0043-1 [CrossRef] .
- Woolson ST, Pouliot MA, Huddleston JI. Primary total hip arthroplasty using an anterior approach and a fracture table: short term results from a community hospital. J Arthroplasty. 2009; 24(7):999–1005 doi:10.1016/j.arth.2009.04.001 [CrossRef] .
- Lewinnek GE, Lewis JL, Tarr R, Compere CL, Zimmerman JR. Dislocations after total hip-replacement arthroplasties. J Bone Joint Surg Am. 1978; 60(2):217–220.
- Woolson ST, Hartford JM, Sawyer A. Results of a method of leg-length equalization for patients undergoing primary total hip replacement. J Arthroplasty. 1999; 14(2):159–164 doi:10.1016/S0883-5403(99)90119-5 [CrossRef] .
- Sendtner E, Borowiak K, Schuster T, et al. Tackling the learning curve: comparison between the anterior, minimally invasive (Micro-hip) and the lateral, transgluteal (Bauer) approach for primary total hip replacement. Arch Orthop Trauma Surg. 2011; 131(5):597–602 doi:10.1007/s00402-010-1174-4 [CrossRef] .
- Berend KR, Lombardi AV, Seng BE, Adams JB. Enhanced early outcomes with the anterior supine intermuscular approach in primary total hip arthroplasty. J Bone Joint Surg Am. 2009; 91(suppl 6):107–120 doi:10.2106/JBJS.I.00525 [CrossRef] .
- Archibeck MJ, White RE Jr, . Learning curve for the two incision total hip replacement. Clin Orthop Relat Res. 2004; (429):232–238 doi:10.1097/01.blo.0000150272.75831.2f [CrossRef] .
- Seng BE, Berend KR, Ajluni AF, Lombardi AV Jr, . Anterior-supine minimally invasive total hip arthroplasty: defining the learning curve. Orthop Clin North Am. 2009; 40(3):343–350 doi:10.1016/j.ocl.2009.01.002 [CrossRef] .
- Bhandari M, Matta JM, Anterior Total Hip Arthroplasty Collaborative Investigators et al. Outcomes following the single incision anterior approach to total hip arthroplasty: a multicenter observational study. Orthop Clin North Am. 2009; 40(3):329–342 doi:10.1016/j.ocl.2009.03.001 [CrossRef] .
- Jewett BA, Collis DK. High complication rate with anterior total hip arthroplasties on a fracture table. Clin Orthop Relat Res. 2011; 469(2):503–507 doi:10.1007/s11999-010-1568-1 [CrossRef] .
- Goulding K, Beaulé PE, Kim PR, Fazekas A. Incidence of lateral femoral cutaneous nerve neuropraxia after anterior approach hip arthroplasty. Clin Orthop Relat Res. 2010; 468(9):2397–2404 doi:10.1007/s11999-010-1406-5 [CrossRef] .
- Bourne RB, Rorabeck CH. Soft tissue balancing: the hip. J Arthroplasty. 2002; 17(4 suppl 1):17–22 doi:10.1054/arth.2002.33263 [CrossRef] .
- DeWal H, Su E, DiCesare PE. Instability following total hip arthroplasty. Am J Orthop. 2003; 32(8):377–382.
|No. of hips (patients)||61 (54)|
|No. of bilateral THAs||7|
|Mean patient age (range), y||55.6 (33–73)|
|No. of men/women||29/25|
|Mean BMI (range), kg/m2||28.3 (18–44)|
|Diagnosis, No. of hips|
| Femoral neck fracture||6|
| Congenital hip dysplasia||1|
|No. of left/right surgeries||31/30|
|Mean blood loss (range), mL||378.69 (100–1000)|
|No. (range of units) of allogeneic blood trans||3 (1–3)|
|Mean operative time, min||110.4 (64–183)|
|Mean hospital stay, d||3.85 (2–13)|
|Complication||No.||Treatment and Outcome|
| Lateral femoral cutaneous nerve damage||1||Recovery after 6 wk|
| Femoral nerve palsy||0|
| Femoral fractures|
| Great trochanteric fracture||3||2 treated with cable fixation|
| Calcar fracture||2||Cable fixation|
| Wound hematomaa||1||Irrigation and debridement|
| Wound superficial infection||1||Irrigation and debridement|
| Deep infection||0|
| Dislocationa||1||Reduction by manual traction|
| Deep venous thrombosis||0|
| Stem subsidence||1||Revision|
| Loose stem||1||Revision|
|Total No. (%) of complications||10 (16.4)|
|No. (%) of hips requiring cable fixation||4 (6.56)|
|No. (%) of hips requiring reoperation||4 (6.56)|
|No. (%) of hips undergoing femoral component revision||2 (3.27)|
|Average acetabular component abduction angle (range), deg||43.79±6.37 (30.44–58.17)|
|Average anteversion angle (range), deg||20.61±2.57 (12.51–24.68)|
|Average postoperative leg-length discrepancy (range), mm||2.24 ±3.22 (0–17.1)|
|Acetabular component abduction angle outliers, No. (%)||6 (9.84)|
|Femoral components in ⩾5° varus, No. (%)||2 (3.28)|
|Leg-length discrepancies >1 cm, No. (%)||2 (3.28)|