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Bilateral simultaneous two-incision minimally invasive total hip arthroplasty
J Orthop Sci (2009) 14:517–524 DOI 10.1007/s00776-009-1358-3
Original article Bilateral simultaneous two-incision minimally invasive total hip arthroplasty SANKET R. DIWANJI1, KYUNG SOON PARK1, TAEK RIM YOON1, HYOUNG YEON SEO2, and JIN SANG WIE3 1
Center for Joint Disease, Chonnam National University Hwasun Hospital, 160 Ilsim-Ri, Hwasun-Eup, Hwasun-Gun, Jeonnam 519-809, Korea 2 Department of Orthopedic Surgery, Chonnam National University Hospital, Gwangju, Korea 3 Orthopedic Department, St. Carollo Hospital, Jeonnam, Korea
Single-stage bilateral total hip arthroplasty (THA) has gained popularity in recent years. It is associated with a shorter hospitalization, decreased morbidity, faster rehabilitation, and lower total cost.1–3 Concerns were initially raised about a higher incidence of complications, such as deep vein thrombosis, pulmonary embo-
lism, and infection, associated with a single-stage procedure,1,4 but series of articles have proven it to be as safe and effective as unilateral THA or bilateral staged procedures.5–8 At the same time, minimally invasive (MI) procedures are advocated to reduce surgical trauma, decrease pain, and speed recovery.9,10 The two-incision technique uses strategically located incisions to insert the prosthesis components into specific intermuscular or internervous planes in an effort to minimize damage to these tissues. However, the two-incision THA (described by Mears and Berger) soon fell under criticism for substantial damage to the abductors and external rotators, with reports of higher rates of complications and reoperations.11–14 With the two-incision THA described by Mears, the patient is operated on in the supine position. They used a modification of the Smith Peterson approach for insertion of the acetabular component; the femoral component is inserted through a small incision situated between the greater trochanter and the iliac crest, centered directly in line with the femoral shaft. We modified this technique and used part of the Watson Jones approach for inserting the acetabular component with the patient in a lateral position. The posterior incision for inserting the femoral component is through an intermuscular interval between the gluteus medius and the piriformis. This technique has consistently given good results with a low rate of complications for unilateral THAs.15 Currently, about 90% of primary THAs done at our institution use this technique. Even though there are many reports about safety and benefits of bilateral simultaneous THA, none has reported about either one-incision or two-incision bilateral simultaneous MI THA. We retrospectively studied our results of bilateral simultaneous two-incision MI THA to analyze the following points.
Offprint requests to: T.R. Yoon Received: September 17, 2008 / Accepted: March 17, 2009
• What are the early clinical and radiological results of bilateral simultaneous two-incision MI THA?
Abstract Background. This study aimed to assess the feasibility of bilateral simultaneous minimally invasive two-incision total hip arthroplasty in terms of clinical and radiological outcomes, complications, and patient satisfaction. Methods. A total of 62 patients, ages 24–69 years, were operated on with bilateral simultaneous minimally invasive total hip arthroplasty using a modified two-incision technique, after which they were followed for an average 41 months. The acetabular component was inserted through part of the Watson-Jones approach, and a femoral component was inserted through a space between the gluteus medius and piriformis tendon. Results. The mean duration of surgery was 180.4 min, and the mean perioperative blood loss was 1513.2 ml. There were no intraoperative complications. Postoperative periprosthetic fracture occurred in two patients and delayed infection in one patient. The average Harris Hip Score improved from 41.8 to 95.3. The WOMAC score improved from an average of 66.2 to 5.0. The average lateral opening angle of the acetabulum was 40°, and the angle of anteversion was 12°. All the femoral components were implanted in neutral to 5° valgus position. Conclusions. Bilateral simultaneous minimally invasive total hip arthroplasty using a modified two-incision technique gave satisfactory clinical, radiological, and functional results. Efforts should be made to prevent perioperative periprosthetic fractures.
Introduction
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• What is the incidence of complications with this technique, and is it safe to work on both hips simultaneously?
Patients and methods Patients
performed with the patient in the lateral position, and general or epidural anesthesia was used. The trunk and pelvis were firmly secured to the operating table with a rigid stabilization system. The hip was prepared and draped using contemporary techniques that allow the affected leg to be mobilized during the procedure. Surgical technique
We retrospectively reviewed the clinical and radiographic data from 76 consecutive patients (152 hips) who underwent bilateral simultaneous MI THA at our institution from August 2003 to December 2006. Bilateral simultaneous MI THA was performed when both hips were symptomatic and could be treated by simple primary THA. The patients should not be obese: body mass index (BMI) <30, except one patient whose BMI was 30.6. The surgeon performed bilateral surgery after having experience with more than 50 unilateral twoincision MI THAs. Criteria for inclusion in the study were surgery performed by a modified two-incision technique and a minimum of 6 months of follow up. The study was approved by the institutional review board. A total of 62 patients were eligible for inclusion in the study (47 men, 15 women). All of the patients were available for follow-up. The patients’ demographic information is summarized in Table 1. Preoperative evaluation included hematological investigations, chest radiography, electrocardiography, and preanesthesia evaluation (for anesthetic risk). All the patients received intravenous cefazolin (1 g) before surgery, and it was continued for 3 days postoperatively (although continuation of prophylactic antibiotics for only 24 h postoperatively is commonly recommended nowadays, at that time 3 days was the common prescription protocol of our department). The size of the acetabular and femoral components and the level of neck resection were determined by templating the preoperative radiographs. Surgery was
Landmarks for the skin incision were identified: the tip and the anterior and posterior borders of the greater trochanter and trochanteric (vastus) ridge. The first incision (6–8 cm) was made over the anterolateral aspect of the hip. The incision started from the point approximately one fingerbreadth posterior to the anterior border of the trochanter and just distal to the trochanteric crest, extending cranially and anteriorly at an angle of 30° to the long axis of the femur. The incision roughly aimed at a point on the iliac crest 3 cm posterior to the anterosuperior iliac spine (Fig. 1). Subcutaneous tissue and fascia lata were divided in line with the skin incision, and the anterior border of the gluteus medius was palpated at its insertion on the greater trochanter. Intermuscular dissection between the gluteus medius and tensor fascia lata was done, carefully ligating the lateral circumflex femoral vessels. The anterior joint capsule was incised in the line of the femoral neck, from the edge of the acetabulum proximally to the intertrochanteric line distally. The femoral neck was osteotomized and femoral head removed. For better visualization of the acetabulum, one or two Steinmann pins were inserted at the posterosuperior side of the acetabulum to retract the gluteus medius. Additionally, two or three curved Hohmann retractors were placed around the acetabulum, usually antero-
Table 1. Demographic details, anesthesia risk, and preoperative diagnosis of patients Parameter Male/female Age (years) Body mass index ASA class 1 2 3
Data 47/15 (75.8%/24.2%) 44.8 ± 11.4 (range 24–69) 23.5 ± 2.8 (range 15.9–30.6)
Preoperative diagnosis Avascular necrosis Osteoarthritis Ankylosing spondylitis Rheumatoid arthritis ASA, American Society of Anesthesiologists
38 (61.3%) 22 (35.5%) 2 (3.2%) 52 5 4 1
Fig. 1. Landmarks (greater trochanter, vastus ridge, anterior superior iliac spine) and sites of anterolateral and posterolateral skin incisions
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inferiorly, posteroinferiorly, and inferiorly (Fig. 2). For better illumination of the narrow operating field, a suction cannula with an attached light source was used. (It was specially designed and not yet commercially available; but even without these instruments, the surgery can be done, although it may be more difficult.) After exposing the acetabulum as shown in Fig. 2, reaming was performed depending on the selected component parameters, and the component was implanted with a targeted lateral opening angle of 40°–45° and anteversion of 15°–20°. The posterior skin incision was then placed over the posterolateral aspect of hip. The hip was flexed to 90°, and a 4- to 6-cm incision was made over the greater trochanter. After dissection through the muscle fibers of gluteus maximus, the fat layer separating the gluteus maximus and medius was exposed. The piriformis, which was the landmark for the intermuscular dissection, was identified after excising the fat (Fig. 3). The
intermuscular dissection between fibers of the piriformis and gluteus medius led to the joint capsule. Under direct visualization, the joint capsule was incised on the posterosuperior side of the hip joint. A starting reamer was introduced into the femoral canal. After preparing the proximal femur with a rasp, the size of the femoral component was determined under fluoroscopy; and the femoral component was inserted (Fig. 4). The femur was then brought anteriorly with traction, external rotation, and extension of the hip. With the hip in external rotation and a bone hook around the neck, the trial femoral head was inserted through an anterior incision. Trial reduction was performed by gentle traction and internal rotation. Leg length was evaluated both clinically and under fluoroscopy (by comparing the level of the lesser trochanters with the obturator foramina). The hip was put through a full range of motion to assess stability. It should be stable in full extension with 45° external rotation and in 90° flexion with 20° adduction
Fig. 2. One Steinman pin and three curved Hohmann retractors are placed around the acetabulum for a better view. *gluteus medius; **acetabular fossa
Fig. 3. The piriformis (*) is a landmark for intermuscular dissection between the gluteus medius and piriformis
A
B
Fig. 4. A Femoral stem is inserted through the posterior incision. B Final evaluation of its position is made with fluoroscopy
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Table 2. Details of operative parameters and blood loss Perioperative parameters Hemoglobin (mg/dl) Hematocrit (%) Drainage (ml) Transfusion (units)
Preoperative
Intraoperative
Postoperative
691.2 (200–1500) 0.5 (0–3.0)
10.5 (7.8–14.9) 30.8 (42.6–11.0) 522.0 (31.0–1830) 2.8 (1.0–4.0)
13.9 (9.8–17.0) 41.5 (29.3–1.0)
Operating time (min) Anesthesia type (no. of patients) General Epidural
180.4 (120–275) 51 (82.3%) 11 (17.7%)
Results are given as the mean and range
and at least 30° internal rotation. The hip was dislocated, the trial head was removed, and the wound was irrigated. The appropriately sized final femoral head was inserted, and the joint was reduced. Leg length and range of motion was checked again. Negative suction drain was placed into the joint through an anterior incision. The anterior capsule can be sutured under direct vision. For posterior capsular closure, we used a long guidewire with a hole for the suture string. Closure of both the anterior and posterior capsules reduced the risk of joint laxity. Fascia lata and subcutaneous tissue were repaired, and the skin was closed. After completion of surgery on one side, all surgical instruments and drapes used for the first side were removed and a new sterile setup was mounted before preparing and draping the second limb. Uncemented prostheses were used in all of the patients. The femoral prostheses used were Cone Prosthesis (Zimmer, Winterthur, Switzerland) in 36 cases and the M/L taper (Zimmer) in 26 cases. The acetabular components used were Secure-fit (Stryker Orthopaedics, Mahwah, NJ, USA) in 48 cases and Fitmore (Zimmer) in 14 cases. Ceramic-on-ceramic articulation was used in 56 cases and metal-on-metal articulation in 6 cases. Postoperative protocol included an abduction pillow between the two legs to prevent dislocation and elastic stockings and limb mobilization to prevent deep vein thrombosis. Quadriceps strengthening exercises were started on the same day, and sitting by the side of the bed was allowed on the day of surgery if the patient was comfortable. Mobilization was recommended with tolerable weight bearing on postoperative day (POD) 1 if the patient’s general condition permitted. All patients were discharged home when they were safely able to mobilize with an ambulatory aid. The factors assessed were blood loss, drop in hemoglobin, transfusion requirement, surgical time, perioperative and early postoperative complications, rehabilitation, and clinical and radiological outcomes. The total blood loss included intraoperative blood loss plus the blood collected in the drainage before removing the drains (Table 2). The intraoperative blood loss
was calculated by drain volume and swab weight. The drains were removed when the 24-h drainage was less than 20 ml. Hemoglobin and hematocrit were measured on the day before surgery and on POD 3. The number of transfusions included packed red cells (PRCs), fresh frozen plasma, and platelet concentrate transfused intraoperatively and postoperatively. Surgical time was calculated from the time of the incision on the first side to complete wound closure on the other side. Postoperative rehabilitation was evaluated by the time of starting use of ambulatory aids, duration of ambulatory aids usage, and time of walking upstairs without using a hand rail. After 2 weeks of surgery, we usually recommended that the patient practice the Buddhist position, which improves hip abduction and external rotation. Patients were followed up at 6 weeks, 3 months, 6 months, 1 year, and then every year. At each visit, the Harris Hip Score,16 the Western Ontario and McMaster Universities Index of Osteoarthritis (WOMAC) score,17 and a radiological evaluation were performed. Radiographs were assessed by a single blinded observer. Radiological evaluations included the lateral opening angle, anteversion of the acetabular component,18 femoral component alignment in the femoral canal, radiological leg-length measurement, percentage of canal fill (calculated using the cross section of the stem divided by that of the femoral canal), and subsidence of the femoral component. The statistical analysis was performed by Student’s t-test using SPSS software (Base 13.0; SPSS, Chicago, IL, USA). The level of significance was set at P < 0.05.
Results A total of 51 patients were operated on under general anesthesia and 11 under epidural anesthesia. The mean duration of surgery was 180.4 min (range 120–275 min). The mean time interval between the two sides was 20 min (range 15–24 min). The mean duration of fluoroscopy was 12 s (range 5–60 s). The preoperative and postoperative hemoglobin and hematocrit levels along
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with total blood loss and transfusion requirements are shown in Table 2. The mean duration of hospitalization was 12.9 days (range 5–39 days). The patient who remained hospitalized for 39 days had a postoperative (POD 5) undisplaced periprosthetic fracture (treated by wiring). A second patient, who had a periprosthetic fracture after a fall while walking on a slippery surface on POD 2, was kept in hospital for 35 days. A third patient remained hospitalized for 28 days, as she was slow with rehabilitation due to previous bilateral knee arthroplasty and generalized weakness. If these three patients are excluded, the mean duration of hospitalization comes down to 8.4 days. Walking with a walker was started on average at 3.7 days (range 1–14 days), and walking with crutches was started on average at 10.3 days (range 1–49 days) postoperatively. Patients were able to walk without support at an average of 48 days (range 14–120 days) and use stairs without support and without any discomfort at an average of 50 days (range 5–150 days). There were no intraoperative cardiopulmonary, gastrointestinal, or respiratory complications. Early postoperative periprosthetic fracture occurred in two patients, one of whom was treated by circlage wiring; the other required revision using a long stem. Both patients recovered uneventfully thereafter. One patient had a chronic infection after 6 months of surgery. Twostage revision using a Prosthesis of Antibiotic Loaded Acrylic Cement (PROSTALAC)19 was done, and there was no clinical or laboratory evidence of infection [normal C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR)] at the time of the last follow-up (5 months after conversion THR). There was no incidence of heterotopic ossification, deep vein thrombosis, or pulmonary embolism.
The average Harris Hip Score improved from 41.8 (range 10–59) preoperatively to 95.3 (range 73–100) postoperatively (P < 0.05) (Table 3). The WOMAC score improved from a median of 66.2 (range 31–96) preoperatively to 5.0 (range 0–19) postoperatively (P < 0.05) (Table 4). Altogether, 49 (79.03%) patients were pain-free at the time of the first follow-up (6 weeks after surgery) and remained pain-free until the last follow-up; the remaining 13 (20.97%) had only slight pain. Among those 13 patients, 3 complained of occasional mild pain at the last follow-up. In all, 50 (80.64%) patients were walking without a limp, and the remaining 12 (19.35%) had only a slight limp at 6 months. Of those 12 patients, 2 had a persistent limp at the final follow-up. In total 58 (93.53%) patients were walking without support, 56 (90.32%) were able to walk unlimited distances, and 55 (88.70%) were able to climb stairs without using a railing. At 3 months, all of the patients (except those treated for periprosthetic fractures) were able to squat and sit in the Buddhist position, which is an integral part of the Oriental lifestyle. The average lateral opening angle of the acetabular component was 40° (range 38.2°–51.4°), and the average angle of anteversion was 12° (range 4.9°–19.6°). All of the femoral components were implanted in neutral to 5° valgus position. Preoperative limb length discrepancy (minimum 5 to maximum 15 mm) was present in 27 patients, 19 of whom had <2 mm limb-length discrepancy and 8 had 2- to 5-mm discrepancy postoperatively. None of the patients had limb-length discrepancy of >5 mm postoperatively (Fig. 5). None of the femoral components showed subsidence of >3 mm. The filling of the femoral canal by the prosthesis was excellent in all cases.
Fig. 5. A Preoperative radiograph of a patient with bilateral avascular necrosis of the femoral head. B Immediate postoperative radiograph shows restoration of limb length and ana-
tomical hip centers. C Radiograph 26 months after surgery shows excellent bone growth around both femoral stems
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Table 3. Details of Harris Hip Score before surgery and at the time of final evaluation Parameter Pain Function Gait (walking maximum distance) Limp Support Distance walked Functional activities Stairs Socks and tie shoes Sitting Enter public transport Absence of deformity Range of motion Total
Maximum
Preoperative
Final follow-up
44
17.4 (2–30)
42.6 (40–44)
11 11 11
4.1 (0–8) 7.0 (0–11) 5.2 (0–11)
10.2 (8–11) 10.4 (3–11) 10.4 (5–11)
4 4 5 1 4 5
1.4 (0–4) 1.6 (0–4) 2.7 (0–5) 0.5 (0–1) 0.5 (0–4) 1.5 (0–5)
3.6 (2–4) 3.4 (0–4) 4.9 (3–5) 1 (1–1) 4 (4–4) 4.7 (4–5)
100
41.8 (10–59)
95.3 (73–100)
Results are the average and range
Table 4. Details of the WOMAC score Parameter
Before surgery
At final follow-up
Pain Stiffness Activities
13.5 (5–20) 5.0 (0–8) 47.7 (22–68)
0.8 (0–5) 0.3 (0–3) 3.9 (0–17)
Total WOMAC score
66.2 (31–96)
5.0 (0–19)
WOMAC, Western Ontario and McMasters Universities Index of Osteoarthritis
Discussion Single-stage bilateral cemented and cementless conventional THAs have been shown to be economical and safe. Two-incision MI THA, however, is a technically demanding procedure with a high learning curve. This study shows that bilateral simultaneous THAs can be performed using modified two-incision techniques with satisfactory clinical-radiological results and an acceptable rate of complications when compared to conventional techniques. There are reports stating that the two-incision technique described by Mears had higher rates of complications and reoperations than a conventional technique.11,13 As we have already described, as an approach we used the interval between the gluteus medius and tensor fascia lata, which avoids risk of injury to the lateral femoral cutaneous nerve. The lateral decubitus and anterolateral approach provides better visualization and orientation of the acetabulum and thus eliminates use of fluoroscopy for implantation of the acetabular component. With the patient in lateral decubitus and the hip flexed and adducted, the intermuscular interval between the gluteus medius and piriformis is better visualized with this technique, thereby avoiding muscle damage and impingement of surgical instruments during the femoral stem insertion.
We have compared our results with those of other authors who have reported series of bilateral simultaneous THA done by conventional technique. AlfaroAdrian et al.5 reported the results of bilateral simultaneous THAs in 95 patients. The average total blood loss was 1579 ml, and the average operating time was 202.6 min. Bhan et al. 6 reported an average total blood loss of 1473.86 ml and an average operation time of 215.58 min in 85 patients who underwent bilateral THAs. We have not found considerable difference in operating time, amount of blood loss, transfusion requirement, or the final Harris Hip Score.3,5,6,7,20 However, the overall incidence of complications was lower in our series (Table 5). The intraoperative femoral fracture has been one of the most commonly reported complications during bilateral simultaneous cementless arthroplasty.3,7,21 We have not encountered any intraoperative femoral fractures in our series. Periprosthetic fractures occurred in two patients during the early postoperative period. Even though postoperative radiographs did not show any fracture lines in our patients, there might have been a linear fracture line leading to a postoperative periprosthetic fracture. That is why we recommend close analysis of intraoperative images for fracture lines, with application of circlage wires in such cases. We also suggest that mobilization in elderly patients should be guarded. Walking was delayed for some elderly individuals, which brought the average duration to 10.3 days; otherwise, most of the patients started walking on the first day after surgery. It is true that walking aids are hardly required after minimally invasive surgery, but in cases of bilateral simultaneous procedures it is necessary for the initial period. Another potential, but most feared, complication after bilateral simultaneous THR is deep vein thrombosis (DVT) and pulmonary embolism.1,4 Recently, several
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Table 5. Perioperative complications of bilateral simultaneous total hip arthroplasty in various series Parameter No. of patients Complications Fracture Intraoperative Postoperative Dislocation Infection Hematoma Nerve palsy Phlebitis Embolism UTI GI Cardiac Cerebrovascular
Bhan et al.6
Ritter et al.3
Alfaro-adrián et al.5
Berend et al.20
Eggli et al.7
Yoon et al. (present series)
85
92
95
450
64
62
—
2
11
1 — 0 6 — — 3 1 5 1 1 0
25 — 0 0 — 1 1 1 — — — —
4 7 — — 0 1 2 5 3 —
6 16 — — 7
1
6 3 12 3
13 2 0 2 8 2 1 —
2 0 1 — 0 0 0 0 0 0 0
UTI, urinary tract infection; GI, gastrointestinal
authors have compared the incidence of DVT and pulmonary embolism in patients undergoing single-stage or two-stage arthroplasty and have not found any significant difference between two groups.5–7 As such, the incidence of DVT is low in Oriental populations.22 In addition, patients were relatively more comfortable after two-incision MI THA and could better comply with the mobilization protocol. That seems the reason for the absence of DVTs in our series. A significant correlation between single-stage bilateral THA and a higher incidence of heterotopic bone formation has been reported.7,23 In our series, none of the patients, even with previous surgery on an ipsilateral hip, developed heterotopic ossification. We believe that the modified two-incision MI THA, with minimal damage to the hip musculature, has the least risk of heterotopic ossification. In addition to the Harris Hip Score, we evaluated our results with the WOMAC score at each follow-up, and it showed significant improvement in the patients’ activity level after surgery (Table 4). In fact, Wykman and Olsson showed in gait analyses after THA that in bilaterally diseased hips normal walking cannot be achieved unless both sides had undergone surgery.24 After unilateral THA, persistent pain and stiffness of the side that had not undergone surgery may decrease rehabilitation of the hip that had been operated on, thus diminishing the patient’s final walking capacity. Radiological evaluation showed acceptable placement of femoral and acetabular components and restoration of limb length. This finding refutes the argument that positioning of the component is compromised during minimally invasive and/or bilateral simultaneous procedures.6 Our study has several limitations. This retrospective study lacked a control group from the same interval.
Different types of acetabular and femoral components were used. Certain measures, such as radiographic outcome parameters, are prone to interobserver variation. We recognize that comparing our results to those of previously published studies precludes any statistical analysis; thus, we cannot be certain whether differences between our results and historical results are significant. Obviously, this limitation applies to any study using historical controls. The results of this study should be interpreted with caution because this technique, like any other MI surgery, has a long learning curve. The low rate of complications in this series can be attributed to the experience of the operating surgeon. One may argue that the duration of hospitalization is relatively long compared to other series of MI THA, but patients are not sent to other rehabilitation facility after discharge from our institution. Walking was delayed in some elderly individuals, which brought the average duration of crutch walking to 10.3 days; otherwise, most of the patients started walking with a walker on the day after surgery. It is true that walking aids are hardly required after minimally invasive surgery, but in cases of bilateral simultaneous procedures it is necessary for the initial period. That is why a patient is discharged only after he or she gets proper gait training and is able to ambulate freely with a walking aid. The insurance providers also allow longer hospital stay here, and the patients came from faraway places, so they prefer to stay until the wound is completely healed.
Conclusions Bilateral simultaneous two-incision minimally invasive THA gives satisfactory clinical and radiological results in comparison with conventional THA. It is safe in
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experienced hands, with no additional risk of complications. It provides an excellent functional outcome and patient satisfaction. Perioperative periprosthetic fracture remains a concern, and every effort should be made to avoid it. Acknowledgments. The authors thank Ms. Sung Hwa Park for her assistance with follow-up and data collection and Harry Fernandez Matta for English corrections. All authors disclose that we have no commercial affiliations as well as consultancies, stock ownership, or patent–licensing arrangements that could be considered to pose a conflict of interest regarding the submitted article.
References 1. Bracy D, Wroblewski BM. Bilateral Charnley arthroplasty as a single procedure: a report on 400 patients. J Bone Joint Surg Br 1981;63:354–6. 2. Reuben JD, Meyers SJ, Cox DD, Elliott M, Watson M, Shim SD. Cost comparison between bilateral simultaneous, staged, and unilateral total joint arthroplasty. J Arthroplasty 1998;13:172–9. 3. Ritter MA, Vaughn BK, Frederick LD. Single-stage, bilateral, cementless total hip arthroplasty. J Arthroplasty 1995;10:151–6. 4. Charnley J. Long-term results of low-friction arthroplasty. Hip 1982;42–9. 5. Alfaro-Adrián J, Bayona F, Rech JA, Murray DW. One- or twostage bilateral total hip replacement. J Arthroplasty 1999;14: 439–45. 6. Bhan S, Pankaj A, Malhotra R. One-or two-stage bilateral total hip arthroplasty: a prospective, randomized, controlled study in an Asian population. J Bone Joint Surg Br 2006;88:298–303. 7. Eggli S, Huckell CB, Ganz R. Bilateral total hip arthroplasty: one stage versus two stage procedure. Clin Orthop 1996;328:108–18. 8. Parvizi J, Tarity TD, Herz A, Klein GR, Sharkey PF, Hozack WJ, et al. Ninety-day mortality after bilateral hip arthroplasty. J Arthroplasty 2006;21:931–4. 9. Berger RA. Mini Incision: two for the price of one. Orthopedics 2002;25:472–98. 10. Berger RA. Total hip arthroplasty using the minimally invasive two-incision approach. Clin Orthop 2003;417:232–41.
S.R. Diwanji et al.: Bilateral simultaneous two-incision MI THA 11. 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: 2432–8. 12. Mardones R, Pagnano MW, Nemanich JP, Trousdale RT. The Frank Stinchfield Award: muscle damage after total hip arthroplasty done with the two-incision and mini-posterior techniques. Clin Orthop 2005;441:63–7. 13. Pagnano MW, Leone J, Lewallen DG, Hanssen AD. Two-incision THA had modest outcomes and some substantial complications. Clin Orthop 2005;441:86–90. 14. Woolson ST. In the absence of evidence ⎯ why bother? A literature review of minimally invasive total hip replacement surgery. Instr Course Lect 2006;55:189–93. 15. Yoon TR, Bae BH, Choi MS. A modified two incision minimally invasive total hip arthroplasty: technique and short-term results. Hip Int 2006;16:28. 16. Harris WH. Traumatic arthritis of the hip after dislocation and acetabular fractures: treatment by mold arthroplasty ⎯ an endresult study using a new method of result evaluation. J Bone Joint Surg Am 1969;51:737–55. 17. Boardman DL, Dorey F, Thomas BJ, Lieberman JR. The accuracy of assessing total hip arthroplasty outcome: a prospective correlation study of walking ability and 2 validated measurement devices. J Arthroplasty 2000;15:200–4. 18. Widmer KH. A simplified method to determine acetabular cup anteversion from plain radiographs. J Arthroplasty 2004;19:387– 90. 19. Duncan CP, Masri BA. The role of antibiotic-loaded cement in the treatment of an infection after a hip replacement. Instr Course Lect 1995;44:305–13. 20. Berend ME, Ritter MA, Harty LD, Davis KE, Keating EM, Meding JB, et al. Simultaneous bilateral versus unilateral total hip arthroplasty an outcomes analysis. J Arthroplasty 2005;20:421– 6. 21. Kim YH. Bilateral cemented and cementless total hip arthroplasty. J Arthroplasty 2002;17:434–40. 22. Kim YH, Oh SH, Kim JS. Incidence and natural history of deepvein thrombosis after total hip arthroplasty: a prospective and randomised clinical study. J Bone Joint Surg Br 2003;85:661–5. 23. Brooker AF, Bowerman JW, Robinson RA, Riley LH Jr. Ectopic ossification following total hip replacement: incidence and a method of classification. J Bone Joint Surg Am 1793;55:1629– 32. 24. Wykman A, Olsson E. Walking ability after total hip replacement: a comparison of gait analysis in unilateral and bilateral cases. J Bone Joint Surg Br 1992;74:53–6.
Original article Bilateral simultaneous two-incision minimally invasive total hip arthroplasty SANKET R. DIWANJI1, KYUNG SOON PARK1, TAEK RIM YOON1, HYOUNG YEON SEO2, and JIN SANG WIE3 1
Center for Joint Disease, Chonnam National University Hwasun Hospital, 160 Ilsim-Ri, Hwasun-Eup, Hwasun-Gun, Jeonnam 519-809, Korea 2 Department of Orthopedic Surgery, Chonnam National University Hospital, Gwangju, Korea 3 Orthopedic Department, St. Carollo Hospital, Jeonnam, Korea
Single-stage bilateral total hip arthroplasty (THA) has gained popularity in recent years. It is associated with a shorter hospitalization, decreased morbidity, faster rehabilitation, and lower total cost.1–3 Concerns were initially raised about a higher incidence of complications, such as deep vein thrombosis, pulmonary embo-
lism, and infection, associated with a single-stage procedure,1,4 but series of articles have proven it to be as safe and effective as unilateral THA or bilateral staged procedures.5–8 At the same time, minimally invasive (MI) procedures are advocated to reduce surgical trauma, decrease pain, and speed recovery.9,10 The two-incision technique uses strategically located incisions to insert the prosthesis components into specific intermuscular or internervous planes in an effort to minimize damage to these tissues. However, the two-incision THA (described by Mears and Berger) soon fell under criticism for substantial damage to the abductors and external rotators, with reports of higher rates of complications and reoperations.11–14 With the two-incision THA described by Mears, the patient is operated on in the supine position. They used a modification of the Smith Peterson approach for insertion of the acetabular component; the femoral component is inserted through a small incision situated between the greater trochanter and the iliac crest, centered directly in line with the femoral shaft. We modified this technique and used part of the Watson Jones approach for inserting the acetabular component with the patient in a lateral position. The posterior incision for inserting the femoral component is through an intermuscular interval between the gluteus medius and the piriformis. This technique has consistently given good results with a low rate of complications for unilateral THAs.15 Currently, about 90% of primary THAs done at our institution use this technique. Even though there are many reports about safety and benefits of bilateral simultaneous THA, none has reported about either one-incision or two-incision bilateral simultaneous MI THA. We retrospectively studied our results of bilateral simultaneous two-incision MI THA to analyze the following points.
Offprint requests to: T.R. Yoon Received: September 17, 2008 / Accepted: March 17, 2009
• What are the early clinical and radiological results of bilateral simultaneous two-incision MI THA?
Abstract Background. This study aimed to assess the feasibility of bilateral simultaneous minimally invasive two-incision total hip arthroplasty in terms of clinical and radiological outcomes, complications, and patient satisfaction. Methods. A total of 62 patients, ages 24–69 years, were operated on with bilateral simultaneous minimally invasive total hip arthroplasty using a modified two-incision technique, after which they were followed for an average 41 months. The acetabular component was inserted through part of the Watson-Jones approach, and a femoral component was inserted through a space between the gluteus medius and piriformis tendon. Results. The mean duration of surgery was 180.4 min, and the mean perioperative blood loss was 1513.2 ml. There were no intraoperative complications. Postoperative periprosthetic fracture occurred in two patients and delayed infection in one patient. The average Harris Hip Score improved from 41.8 to 95.3. The WOMAC score improved from an average of 66.2 to 5.0. The average lateral opening angle of the acetabulum was 40°, and the angle of anteversion was 12°. All the femoral components were implanted in neutral to 5° valgus position. Conclusions. Bilateral simultaneous minimally invasive total hip arthroplasty using a modified two-incision technique gave satisfactory clinical, radiological, and functional results. Efforts should be made to prevent perioperative periprosthetic fractures.
Introduction
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• What is the incidence of complications with this technique, and is it safe to work on both hips simultaneously?
Patients and methods Patients
performed with the patient in the lateral position, and general or epidural anesthesia was used. The trunk and pelvis were firmly secured to the operating table with a rigid stabilization system. The hip was prepared and draped using contemporary techniques that allow the affected leg to be mobilized during the procedure. Surgical technique
We retrospectively reviewed the clinical and radiographic data from 76 consecutive patients (152 hips) who underwent bilateral simultaneous MI THA at our institution from August 2003 to December 2006. Bilateral simultaneous MI THA was performed when both hips were symptomatic and could be treated by simple primary THA. The patients should not be obese: body mass index (BMI) <30, except one patient whose BMI was 30.6. The surgeon performed bilateral surgery after having experience with more than 50 unilateral twoincision MI THAs. Criteria for inclusion in the study were surgery performed by a modified two-incision technique and a minimum of 6 months of follow up. The study was approved by the institutional review board. A total of 62 patients were eligible for inclusion in the study (47 men, 15 women). All of the patients were available for follow-up. The patients’ demographic information is summarized in Table 1. Preoperative evaluation included hematological investigations, chest radiography, electrocardiography, and preanesthesia evaluation (for anesthetic risk). All the patients received intravenous cefazolin (1 g) before surgery, and it was continued for 3 days postoperatively (although continuation of prophylactic antibiotics for only 24 h postoperatively is commonly recommended nowadays, at that time 3 days was the common prescription protocol of our department). The size of the acetabular and femoral components and the level of neck resection were determined by templating the preoperative radiographs. Surgery was
Landmarks for the skin incision were identified: the tip and the anterior and posterior borders of the greater trochanter and trochanteric (vastus) ridge. The first incision (6–8 cm) was made over the anterolateral aspect of the hip. The incision started from the point approximately one fingerbreadth posterior to the anterior border of the trochanter and just distal to the trochanteric crest, extending cranially and anteriorly at an angle of 30° to the long axis of the femur. The incision roughly aimed at a point on the iliac crest 3 cm posterior to the anterosuperior iliac spine (Fig. 1). Subcutaneous tissue and fascia lata were divided in line with the skin incision, and the anterior border of the gluteus medius was palpated at its insertion on the greater trochanter. Intermuscular dissection between the gluteus medius and tensor fascia lata was done, carefully ligating the lateral circumflex femoral vessels. The anterior joint capsule was incised in the line of the femoral neck, from the edge of the acetabulum proximally to the intertrochanteric line distally. The femoral neck was osteotomized and femoral head removed. For better visualization of the acetabulum, one or two Steinmann pins were inserted at the posterosuperior side of the acetabulum to retract the gluteus medius. Additionally, two or three curved Hohmann retractors were placed around the acetabulum, usually antero-
Table 1. Demographic details, anesthesia risk, and preoperative diagnosis of patients Parameter Male/female Age (years) Body mass index ASA class 1 2 3
Data 47/15 (75.8%/24.2%) 44.8 ± 11.4 (range 24–69) 23.5 ± 2.8 (range 15.9–30.6)
Preoperative diagnosis Avascular necrosis Osteoarthritis Ankylosing spondylitis Rheumatoid arthritis ASA, American Society of Anesthesiologists
38 (61.3%) 22 (35.5%) 2 (3.2%) 52 5 4 1
Fig. 1. Landmarks (greater trochanter, vastus ridge, anterior superior iliac spine) and sites of anterolateral and posterolateral skin incisions
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inferiorly, posteroinferiorly, and inferiorly (Fig. 2). For better illumination of the narrow operating field, a suction cannula with an attached light source was used. (It was specially designed and not yet commercially available; but even without these instruments, the surgery can be done, although it may be more difficult.) After exposing the acetabulum as shown in Fig. 2, reaming was performed depending on the selected component parameters, and the component was implanted with a targeted lateral opening angle of 40°–45° and anteversion of 15°–20°. The posterior skin incision was then placed over the posterolateral aspect of hip. The hip was flexed to 90°, and a 4- to 6-cm incision was made over the greater trochanter. After dissection through the muscle fibers of gluteus maximus, the fat layer separating the gluteus maximus and medius was exposed. The piriformis, which was the landmark for the intermuscular dissection, was identified after excising the fat (Fig. 3). The
intermuscular dissection between fibers of the piriformis and gluteus medius led to the joint capsule. Under direct visualization, the joint capsule was incised on the posterosuperior side of the hip joint. A starting reamer was introduced into the femoral canal. After preparing the proximal femur with a rasp, the size of the femoral component was determined under fluoroscopy; and the femoral component was inserted (Fig. 4). The femur was then brought anteriorly with traction, external rotation, and extension of the hip. With the hip in external rotation and a bone hook around the neck, the trial femoral head was inserted through an anterior incision. Trial reduction was performed by gentle traction and internal rotation. Leg length was evaluated both clinically and under fluoroscopy (by comparing the level of the lesser trochanters with the obturator foramina). The hip was put through a full range of motion to assess stability. It should be stable in full extension with 45° external rotation and in 90° flexion with 20° adduction
Fig. 2. One Steinman pin and three curved Hohmann retractors are placed around the acetabulum for a better view. *gluteus medius; **acetabular fossa
Fig. 3. The piriformis (*) is a landmark for intermuscular dissection between the gluteus medius and piriformis
A
B
Fig. 4. A Femoral stem is inserted through the posterior incision. B Final evaluation of its position is made with fluoroscopy
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Table 2. Details of operative parameters and blood loss Perioperative parameters Hemoglobin (mg/dl) Hematocrit (%) Drainage (ml) Transfusion (units)
Preoperative
Intraoperative
Postoperative
691.2 (200–1500) 0.5 (0–3.0)
10.5 (7.8–14.9) 30.8 (42.6–11.0) 522.0 (31.0–1830) 2.8 (1.0–4.0)
13.9 (9.8–17.0) 41.5 (29.3–1.0)
Operating time (min) Anesthesia type (no. of patients) General Epidural
180.4 (120–275) 51 (82.3%) 11 (17.7%)
Results are given as the mean and range
and at least 30° internal rotation. The hip was dislocated, the trial head was removed, and the wound was irrigated. The appropriately sized final femoral head was inserted, and the joint was reduced. Leg length and range of motion was checked again. Negative suction drain was placed into the joint through an anterior incision. The anterior capsule can be sutured under direct vision. For posterior capsular closure, we used a long guidewire with a hole for the suture string. Closure of both the anterior and posterior capsules reduced the risk of joint laxity. Fascia lata and subcutaneous tissue were repaired, and the skin was closed. After completion of surgery on one side, all surgical instruments and drapes used for the first side were removed and a new sterile setup was mounted before preparing and draping the second limb. Uncemented prostheses were used in all of the patients. The femoral prostheses used were Cone Prosthesis (Zimmer, Winterthur, Switzerland) in 36 cases and the M/L taper (Zimmer) in 26 cases. The acetabular components used were Secure-fit (Stryker Orthopaedics, Mahwah, NJ, USA) in 48 cases and Fitmore (Zimmer) in 14 cases. Ceramic-on-ceramic articulation was used in 56 cases and metal-on-metal articulation in 6 cases. Postoperative protocol included an abduction pillow between the two legs to prevent dislocation and elastic stockings and limb mobilization to prevent deep vein thrombosis. Quadriceps strengthening exercises were started on the same day, and sitting by the side of the bed was allowed on the day of surgery if the patient was comfortable. Mobilization was recommended with tolerable weight bearing on postoperative day (POD) 1 if the patient’s general condition permitted. All patients were discharged home when they were safely able to mobilize with an ambulatory aid. The factors assessed were blood loss, drop in hemoglobin, transfusion requirement, surgical time, perioperative and early postoperative complications, rehabilitation, and clinical and radiological outcomes. The total blood loss included intraoperative blood loss plus the blood collected in the drainage before removing the drains (Table 2). The intraoperative blood loss
was calculated by drain volume and swab weight. The drains were removed when the 24-h drainage was less than 20 ml. Hemoglobin and hematocrit were measured on the day before surgery and on POD 3. The number of transfusions included packed red cells (PRCs), fresh frozen plasma, and platelet concentrate transfused intraoperatively and postoperatively. Surgical time was calculated from the time of the incision on the first side to complete wound closure on the other side. Postoperative rehabilitation was evaluated by the time of starting use of ambulatory aids, duration of ambulatory aids usage, and time of walking upstairs without using a hand rail. After 2 weeks of surgery, we usually recommended that the patient practice the Buddhist position, which improves hip abduction and external rotation. Patients were followed up at 6 weeks, 3 months, 6 months, 1 year, and then every year. At each visit, the Harris Hip Score,16 the Western Ontario and McMaster Universities Index of Osteoarthritis (WOMAC) score,17 and a radiological evaluation were performed. Radiographs were assessed by a single blinded observer. Radiological evaluations included the lateral opening angle, anteversion of the acetabular component,18 femoral component alignment in the femoral canal, radiological leg-length measurement, percentage of canal fill (calculated using the cross section of the stem divided by that of the femoral canal), and subsidence of the femoral component. The statistical analysis was performed by Student’s t-test using SPSS software (Base 13.0; SPSS, Chicago, IL, USA). The level of significance was set at P < 0.05.
Results A total of 51 patients were operated on under general anesthesia and 11 under epidural anesthesia. The mean duration of surgery was 180.4 min (range 120–275 min). The mean time interval between the two sides was 20 min (range 15–24 min). The mean duration of fluoroscopy was 12 s (range 5–60 s). The preoperative and postoperative hemoglobin and hematocrit levels along
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with total blood loss and transfusion requirements are shown in Table 2. The mean duration of hospitalization was 12.9 days (range 5–39 days). The patient who remained hospitalized for 39 days had a postoperative (POD 5) undisplaced periprosthetic fracture (treated by wiring). A second patient, who had a periprosthetic fracture after a fall while walking on a slippery surface on POD 2, was kept in hospital for 35 days. A third patient remained hospitalized for 28 days, as she was slow with rehabilitation due to previous bilateral knee arthroplasty and generalized weakness. If these three patients are excluded, the mean duration of hospitalization comes down to 8.4 days. Walking with a walker was started on average at 3.7 days (range 1–14 days), and walking with crutches was started on average at 10.3 days (range 1–49 days) postoperatively. Patients were able to walk without support at an average of 48 days (range 14–120 days) and use stairs without support and without any discomfort at an average of 50 days (range 5–150 days). There were no intraoperative cardiopulmonary, gastrointestinal, or respiratory complications. Early postoperative periprosthetic fracture occurred in two patients, one of whom was treated by circlage wiring; the other required revision using a long stem. Both patients recovered uneventfully thereafter. One patient had a chronic infection after 6 months of surgery. Twostage revision using a Prosthesis of Antibiotic Loaded Acrylic Cement (PROSTALAC)19 was done, and there was no clinical or laboratory evidence of infection [normal C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR)] at the time of the last follow-up (5 months after conversion THR). There was no incidence of heterotopic ossification, deep vein thrombosis, or pulmonary embolism.
The average Harris Hip Score improved from 41.8 (range 10–59) preoperatively to 95.3 (range 73–100) postoperatively (P < 0.05) (Table 3). The WOMAC score improved from a median of 66.2 (range 31–96) preoperatively to 5.0 (range 0–19) postoperatively (P < 0.05) (Table 4). Altogether, 49 (79.03%) patients were pain-free at the time of the first follow-up (6 weeks after surgery) and remained pain-free until the last follow-up; the remaining 13 (20.97%) had only slight pain. Among those 13 patients, 3 complained of occasional mild pain at the last follow-up. In all, 50 (80.64%) patients were walking without a limp, and the remaining 12 (19.35%) had only a slight limp at 6 months. Of those 12 patients, 2 had a persistent limp at the final follow-up. In total 58 (93.53%) patients were walking without support, 56 (90.32%) were able to walk unlimited distances, and 55 (88.70%) were able to climb stairs without using a railing. At 3 months, all of the patients (except those treated for periprosthetic fractures) were able to squat and sit in the Buddhist position, which is an integral part of the Oriental lifestyle. The average lateral opening angle of the acetabular component was 40° (range 38.2°–51.4°), and the average angle of anteversion was 12° (range 4.9°–19.6°). All of the femoral components were implanted in neutral to 5° valgus position. Preoperative limb length discrepancy (minimum 5 to maximum 15 mm) was present in 27 patients, 19 of whom had <2 mm limb-length discrepancy and 8 had 2- to 5-mm discrepancy postoperatively. None of the patients had limb-length discrepancy of >5 mm postoperatively (Fig. 5). None of the femoral components showed subsidence of >3 mm. The filling of the femoral canal by the prosthesis was excellent in all cases.
Fig. 5. A Preoperative radiograph of a patient with bilateral avascular necrosis of the femoral head. B Immediate postoperative radiograph shows restoration of limb length and ana-
tomical hip centers. C Radiograph 26 months after surgery shows excellent bone growth around both femoral stems
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Table 3. Details of Harris Hip Score before surgery and at the time of final evaluation Parameter Pain Function Gait (walking maximum distance) Limp Support Distance walked Functional activities Stairs Socks and tie shoes Sitting Enter public transport Absence of deformity Range of motion Total
Maximum
Preoperative
Final follow-up
44
17.4 (2–30)
42.6 (40–44)
11 11 11
4.1 (0–8) 7.0 (0–11) 5.2 (0–11)
10.2 (8–11) 10.4 (3–11) 10.4 (5–11)
4 4 5 1 4 5
1.4 (0–4) 1.6 (0–4) 2.7 (0–5) 0.5 (0–1) 0.5 (0–4) 1.5 (0–5)
3.6 (2–4) 3.4 (0–4) 4.9 (3–5) 1 (1–1) 4 (4–4) 4.7 (4–5)
100
41.8 (10–59)
95.3 (73–100)
Results are the average and range
Table 4. Details of the WOMAC score Parameter
Before surgery
At final follow-up
Pain Stiffness Activities
13.5 (5–20) 5.0 (0–8) 47.7 (22–68)
0.8 (0–5) 0.3 (0–3) 3.9 (0–17)
Total WOMAC score
66.2 (31–96)
5.0 (0–19)
WOMAC, Western Ontario and McMasters Universities Index of Osteoarthritis
Discussion Single-stage bilateral cemented and cementless conventional THAs have been shown to be economical and safe. Two-incision MI THA, however, is a technically demanding procedure with a high learning curve. This study shows that bilateral simultaneous THAs can be performed using modified two-incision techniques with satisfactory clinical-radiological results and an acceptable rate of complications when compared to conventional techniques. There are reports stating that the two-incision technique described by Mears had higher rates of complications and reoperations than a conventional technique.11,13 As we have already described, as an approach we used the interval between the gluteus medius and tensor fascia lata, which avoids risk of injury to the lateral femoral cutaneous nerve. The lateral decubitus and anterolateral approach provides better visualization and orientation of the acetabulum and thus eliminates use of fluoroscopy for implantation of the acetabular component. With the patient in lateral decubitus and the hip flexed and adducted, the intermuscular interval between the gluteus medius and piriformis is better visualized with this technique, thereby avoiding muscle damage and impingement of surgical instruments during the femoral stem insertion.
We have compared our results with those of other authors who have reported series of bilateral simultaneous THA done by conventional technique. AlfaroAdrian et al.5 reported the results of bilateral simultaneous THAs in 95 patients. The average total blood loss was 1579 ml, and the average operating time was 202.6 min. Bhan et al. 6 reported an average total blood loss of 1473.86 ml and an average operation time of 215.58 min in 85 patients who underwent bilateral THAs. We have not found considerable difference in operating time, amount of blood loss, transfusion requirement, or the final Harris Hip Score.3,5,6,7,20 However, the overall incidence of complications was lower in our series (Table 5). The intraoperative femoral fracture has been one of the most commonly reported complications during bilateral simultaneous cementless arthroplasty.3,7,21 We have not encountered any intraoperative femoral fractures in our series. Periprosthetic fractures occurred in two patients during the early postoperative period. Even though postoperative radiographs did not show any fracture lines in our patients, there might have been a linear fracture line leading to a postoperative periprosthetic fracture. That is why we recommend close analysis of intraoperative images for fracture lines, with application of circlage wires in such cases. We also suggest that mobilization in elderly patients should be guarded. Walking was delayed for some elderly individuals, which brought the average duration to 10.3 days; otherwise, most of the patients started walking on the first day after surgery. It is true that walking aids are hardly required after minimally invasive surgery, but in cases of bilateral simultaneous procedures it is necessary for the initial period. Another potential, but most feared, complication after bilateral simultaneous THR is deep vein thrombosis (DVT) and pulmonary embolism.1,4 Recently, several
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Table 5. Perioperative complications of bilateral simultaneous total hip arthroplasty in various series Parameter No. of patients Complications Fracture Intraoperative Postoperative Dislocation Infection Hematoma Nerve palsy Phlebitis Embolism UTI GI Cardiac Cerebrovascular
Bhan et al.6
Ritter et al.3
Alfaro-adrián et al.5
Berend et al.20
Eggli et al.7
Yoon et al. (present series)
85
92
95
450
64
62
—
2
11
1 — 0 6 — — 3 1 5 1 1 0
25 — 0 0 — 1 1 1 — — — —
4 7 — — 0 1 2 5 3 —
6 16 — — 7
1
6 3 12 3
13 2 0 2 8 2 1 —
2 0 1 — 0 0 0 0 0 0 0
UTI, urinary tract infection; GI, gastrointestinal
authors have compared the incidence of DVT and pulmonary embolism in patients undergoing single-stage or two-stage arthroplasty and have not found any significant difference between two groups.5–7 As such, the incidence of DVT is low in Oriental populations.22 In addition, patients were relatively more comfortable after two-incision MI THA and could better comply with the mobilization protocol. That seems the reason for the absence of DVTs in our series. A significant correlation between single-stage bilateral THA and a higher incidence of heterotopic bone formation has been reported.7,23 In our series, none of the patients, even with previous surgery on an ipsilateral hip, developed heterotopic ossification. We believe that the modified two-incision MI THA, with minimal damage to the hip musculature, has the least risk of heterotopic ossification. In addition to the Harris Hip Score, we evaluated our results with the WOMAC score at each follow-up, and it showed significant improvement in the patients’ activity level after surgery (Table 4). In fact, Wykman and Olsson showed in gait analyses after THA that in bilaterally diseased hips normal walking cannot be achieved unless both sides had undergone surgery.24 After unilateral THA, persistent pain and stiffness of the side that had not undergone surgery may decrease rehabilitation of the hip that had been operated on, thus diminishing the patient’s final walking capacity. Radiological evaluation showed acceptable placement of femoral and acetabular components and restoration of limb length. This finding refutes the argument that positioning of the component is compromised during minimally invasive and/or bilateral simultaneous procedures.6 Our study has several limitations. This retrospective study lacked a control group from the same interval.
Different types of acetabular and femoral components were used. Certain measures, such as radiographic outcome parameters, are prone to interobserver variation. We recognize that comparing our results to those of previously published studies precludes any statistical analysis; thus, we cannot be certain whether differences between our results and historical results are significant. Obviously, this limitation applies to any study using historical controls. The results of this study should be interpreted with caution because this technique, like any other MI surgery, has a long learning curve. The low rate of complications in this series can be attributed to the experience of the operating surgeon. One may argue that the duration of hospitalization is relatively long compared to other series of MI THA, but patients are not sent to other rehabilitation facility after discharge from our institution. Walking was delayed in some elderly individuals, which brought the average duration of crutch walking to 10.3 days; otherwise, most of the patients started walking with a walker on the day after surgery. It is true that walking aids are hardly required after minimally invasive surgery, but in cases of bilateral simultaneous procedures it is necessary for the initial period. That is why a patient is discharged only after he or she gets proper gait training and is able to ambulate freely with a walking aid. The insurance providers also allow longer hospital stay here, and the patients came from faraway places, so they prefer to stay until the wound is completely healed.
Conclusions Bilateral simultaneous two-incision minimally invasive THA gives satisfactory clinical and radiological results in comparison with conventional THA. It is safe in
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experienced hands, with no additional risk of complications. It provides an excellent functional outcome and patient satisfaction. Perioperative periprosthetic fracture remains a concern, and every effort should be made to avoid it. Acknowledgments. The authors thank Ms. Sung Hwa Park for her assistance with follow-up and data collection and Harry Fernandez Matta for English corrections. All authors disclose that we have no commercial affiliations as well as consultancies, stock ownership, or patent–licensing arrangements that could be considered to pose a conflict of interest regarding the submitted article.
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