Surgical treatment of acetabular fractures

G. PETSATODES, J. CHRISTOFORIDES, P. ANTONARAKOS, I. HATZOKOS, D. KARATAGLIS,
J. POURNARAS
First Orthopaedic Department, Aristotelian University of Thessaloniki,
"G. Papanikolaou" General Hospital

 

ABSTRACT
The results of operative treatment of acetabular fractures, as well as its role in the occurrence of post-traumatic osteoarthritis are presented. From 1990 to 2000, fifty patients had an open reduction and internal fixation of an acetabular fracture. Thirty-two patients were male and eighteen were female, with an age ranging from 18 to 71 years (average: 37,8 years). The mechanism of injury was a motor vehicle accident in most cases (84%). The fractures were classified both according to the AO and according to the Letournel-Judet classification. The patients were operated upon within 1-24 days (average: 10 days). The Kocher-Langenbeck surgical approach was used, and in 14 cases it was supplemented with an osteotomy of the greater trochanter. Osteosynthesis was achieved with either lag screws alone or with a combination of lag screws and a buttress plate. Indomethacin 75mg daily for 6 weeks was administered as a prophylaxis against heterotopic ossification. Follow-up ranged from 2-10 years (average: 5,8 years). Clinical evaluation according to the D' Aubigne-Postel scoring system gave 20 excellent (40%), 18 good (36%), 5 fair (10%) and 7 poor (14%) results. Early postoperative complications included 5 cases of common peroneal nerve palsy and 3 cases of wound infection. Late complications included 1 case of avascular necrosis of the femoral head, 12 cases of post-traumatic osteoarthritis (24%) and 5 cases of Brooker III heterotopic ossification (10%). Operative treatment of acetabular fractures although demanding bears very good results. Post-traumatic arthritis remains a common complication, even if care is taken for the anatomic reduction of the fracture.

Key words: Posterior hip dislocation, acetabular fractures, surgical treament.

INTRODUCTION
Acetabular fractures, especially displaced ones, constitute serious intra-articular injuries, caused by high-energy trauma and are often accompanied by posterior hip dislocation or other musculoskeletal injuries that may significantly affect the treatment protocol as well as the end-result [6,7,8]. Displacement of the fracture ends by more than 2mm is known to increase the danger of post-traumatic arthritis and lead to a poor functional outcome. Surgical treatment of displaced acetabular fractures is considered the treatment of choice today, because it ensures the best possible anatomical reconstruction of the joint surface, thus increasing the chances of a satisfactory functional result [6,8,10,16].
The aim of this study is to look into the results of surgical treatment of acetabular fractures, to evaluate the functional outcome, as well as to establish the role of surgical treatment in the occurrence of post-traumatic arthritis of the hip.

Picture 1.
A. A1 fracture in a 26 year-old patient.
B. CT-scan of this fracture.
C. Fixation with 4,0mm interfragmentary screws. Excellent result.

PATIENTS AND METHODS
From March 1990 to May 2000, 72 acetabular fractures were managed in our unit. Out of those fractures 22 were managed conservatively, while 50 (77%) were treated surgically. Criteria for conservative management included displacement of the fracture ends by less than 5mm and retained continuity of the acetabular dome as shown in three x-ray projections with no traction applied and a CT-scan [4,7,8,9,14]. Fractures that were displaced by more than 5mm with concomitant disruption of the bony continuity of the acetabular dome were treated surgically. Thirty-two men and 18 women with an age ranging from 18-71 years (mean: 37,8 years) were operated. The main cause of injury was a road traffic accident (84% of cases). Pre-operative radiologic evaluation constituted of a plain AP view of the pelvis as well as oblique Judet views and a CT-scan. Fractures were classified according to both the AO 15 and the Letournel-Judet 6 classification. According to the AO classification 22 type-A fractures (44%) (14 A1 and 8 A2), 24 type-B fractures (48%) (10 B1, 12 B2 and 2 B3) and 4 type C fractures (8%) (3 C1 and 1 C2) were included (table 1). According to the Letournel-Judet classification 29 simple (58%) and 21 complex (42%) were included. Out of the simple fractures, 14 were located in the anterior wall (28%), 9 in the posterior wall (18%) and 6 were transverse (12%). Out of the complex fractures, 4 combined a posterior wall and a posterior column element (8%), 10 involved the posterior wall and included a transverse fracture line as well (10%) while the remaining 2 involved both columns (4%) (table 2).
Posterior dislocation of the hip was present in 32 patients (64%); 28 were reduced with immediate closed reduction, while the remaining 4 were reduced intra-operatively. Pre-operative skeletal traction was applied on all patients.
Open reduction and internal fixation was performed 1-24 days following the initial injury (mean: 10). In all cases the fracture was approached via a Kocher-Langenbeck approach with the patient on the side. In 14 cases (28%) a trochanteric osteotomy was used to enhance exposure.
The main operative goal was to achieve reconstruction of the anatomy of the innominate bone and the articular surface of the acetabulum. Reconstruction of the anterior column was not attempted in any of our cases. Fixation of the fracture was achieved with 4,0mm or 3,5mm interfragmentary screws when the fracture was confined to the posterior wall, or with interfragmentary screws combined with a reconstruction plate in all other fracture types. Intra-operative findings included lose intra-articular osteochondral fragments in 38 cases (76%), chondral lesion of either the acetabulum or the femoral head in 21 hips (42%) and depression of the articular cartilage of the acetabulum in 9 hips (18%).
Post-operative skeletal traction was employed in all patients for 3 weeks depending on fracture severity and the stability of internal fixation achieved. Following this period patients mobilised non-weight bearing for three months, partial weight bearing for the following three months and started fully weight bearing from 6 months onwards. All patients received 25mg of indomethacin three times daily for 6 weeks as a protection against heterotopic ossification and low molecular weight heparin thromboprophylaxis for 2 months.

Picture 2 .
A. B2 fracture in a 28 year-old patient compounded with posterior dislocation.
B. CT-scan of this fracture.
C. Fixation with a combination of interfragmentary screws and plate. Excellent result.

RESULTS
All patients were followed 3,6,and 12 months post-operatively and subsequently at two years when the operative outcome had been finalised and final evaluation of fracture healing and functional outcome could be performed quite reliably. For patients who showed signs of post-traumatic osteoarthritis follow-up continued yearly thereafter. On last follow-up 42 patients were examined and the remaining 8 were interviewed by telephone and their answers were evaluated in conjunction with previous follow-up appointment results. Post-operative follow-up ranged from 2 to 10 years with a mean of 5,8 years. Fracture fixation outcome was radiologically evaluated with an AP X-ray of the pelvis and patients were functionally evaluated with the D'Aubigne-Postel scoring system 12.
Fracture reduction and fixation was checked with early post-operative X-rays, while at a later stage X-rays helped in the evaluation of the presence of complications such as osteonecrosis, post-traumatic osteoarthritis and heterotopic ossification. Based on the radiologic criteria used by Matta 8 the result was considered excellent when the hip joint had a normal appearance on plain X-rays, good when a small degree of subchondral sclerosis, joint space narrowing and osteophytosis were present, fair when joint space was narrowed up to 50% and considerable osteophytosis and subchondral sclerosis were present and poor when the joint space was narrowed by more than 50%, a degree of femoral head collapse as well as clear signs of osteoarthritis were present. Based on the above-mentioned radiologic criteria the result was excellent in 20 patients (40%), good in 16 (32%), fair in 5 (10%) and poor in 9 (18%).
Clinical assessment was performed according to the D'Aubigne-Postel scoring system, with pain, ability to mobilize and joint mobility being evaluated. According to those criteria our results were excellent (17-18 points) in 20 patients (40%), good (15-16 points) in 18 (36%), fair (12-14 points) in 5 (10%) and poor (<12 points) in 7 (14%).
Results were evaluated as regards the fracture type according to AO. In this procedure it was evident that out of the 22 type A fractures 16 (73%) had an excellent or good result and the remaining 6 (27%) a fair or poor. Out of the 24 type B fractures had an excellent or good result and the remaining 4 (16%) affair or poor. Out of the 4 type C fractures 2 (50%) had an excellent or good result and the remaining 2 (50%) a fair or poor (table 3 figures 1,2).
Early complications included immediate post-operative peroneal nerve palsy in 5 patients (10%), wound infection in 3 (6%) and posterior dislocation in one patient, due to delayed osteosynthesis and insufficient reconstruction of the posterior wall. Sciatic or other nerve paresis was not recorded. Out of the 5 cases of peroneal nerve palsy 4 recovered completely, while the fifth case had only partial recovery. Wound infection was treated successfully with surgical debridement and antibiotics in two cases. The third case wound infection was the one where with posterior dislocation occurred as well. Despite wound debridement infection was not successfully controlled and multiple relapses occurred. The final result was poor.
Late complications included femoral head osteonecrosis in one patient (figure 3), post-traumatic osteoarthritis in 12 patients (24%) and heterotopic ossification Grade III according to Brooker 1 in 5 cases (10%). Seven patients with post-traumatic osteoarthritis have already undergone a total hip replacement.

Picture 3.
A. A2 fracture in a 70 year-old patient.
B. Immediate post-operative X-ray showing restoration of the anatomy of the acetabulum.
C. Final poor result with screw breakage and development of post-traumatic OA.

 

DISCUSSION
Surgical treatment of displaced acetabular fractures is beyond any doubt the treatment of choice, because it gives the better chances for anatomical reconstruction of the joint [6,7,8,10,16]. The goal of surgical treatment is to provide the means for good function and excellent range of painless motion in the injured hip for the rest of the patient's life [5,7,8,14]. By far the commonest complication of these fractures is post-traumatic osteoarthritis of the hip, which often leads to a total hip replacement [5,7,8]. Other less frequent complications are osteonecrosis of the femoral head, osseous defects of the acetabulum, shortening of the affected limb and heterotopic ossification [3,5-8,17].
The main criterion for surgical management is the degree of displacement of the fracture ends of the acetabulum. In our series the criterion used for surgical management was a fracture displacement of more than 5mm. This was the criterion suggested by Matta 8 and Johnson et al 4. Patients in our series were operated upon between the 1st and 24th day following the initial injury, with a mean of 10 days. Analysis of the results showed a better outcome in patients operated upon until the 5th-7th day following the initial injury. Delay of operative management was usually the case in polytrauma patients with various other injuries that were in ITU for prolonged periods of time. The result of surgical management was overall worse than the result for patients operated earlier on. It is therefore thought that acetabular fractures should be operated upon as early as possible within the first post-injury days in order for the outcome to be more favourable [6,8,10,11]. The approach used in our series was a Kocher-Langenbeck approach with the patient on the side. Most authors prefer to place the patient in a prone position for the approach of such fractures [6,8,11]. We feel that the approach and positioning we used, with or without a trochanteric osteotomy, allow for adequate exposure for the fixation of the fractures of the posterior of the acetabulum, which are the commonest fracture pattern. In our patients a fracture of the posterior elements was found in 96% of cases. The goal of operative management was anatomic reduction of the fracture and subsequent stable internal fixation, with either interfragmentary screws alone or with a combination of interfragmentary screws and a reconstruction plate. Anatomic reduction was achieved in 78% of cases, which is considered to be very satisfactory [8,10,11,16]. The post-operative application of skeletal traction is a contentious issue and most authors nowadays suggest that it should not be used provided that the internal fixation achieved is rigid enough [7,8,10]. We have used skeletal traction post-operatively in all our patients, which in turn has prolonged their rehabilitation time, but on the other hand further secured the original satisfactory fixation. We feel that implementation of post-operative skeletal traction can be shortened or even totally abolished in cases where internal fixation is stable enough.
Our results were evaluated on the basis of both clinical and radiologic criteria, as well as according to fracture type [8,10,14]. Radiologic evaluation showed 72% of excellent or good results and 28% of fair or poor results, while clinical evaluation showed 76% of excellent or good results and 24% of fair or poor results. An analogy between clinical and radiologic results was recorded in our cases, a fact supported by the literature as well [7,8,14]. The rate of excellent and good results in our series (76%) is considered very satisfactory. Similar results have been reported by Letournel 6, Matta 7,8, Mayo 10 and Moed 14.
If results were associated with the fracture type it was clear that simple fractures gave a better outcome than complex fractures, as expected, because in simple fractures anatomic reduction was achieved more often.
Peroneal nerve palsy was recorded in 5 cases and the recovery rate was 90%. Nerve injury is a common complication due to either the initial injury itself or to intraoperative manipulations in order to achieve fracture reduction. Matta 8 in a series of 262 fractures reports injuries of the sciatic and femoral nerves as well. The end result though was not affected from this complication.
Heterotopic ossification was not a serious problem in our series of patients. It occurred in 5 patients (10%) but did not cause functional problems to them. The rates of heterotopic ossification reported by various authors in series of acetabular fractures surpass 50% in some series [2,3,5,8,16]. Matta 8 in a series of 262 patients where no prophylaxis against heterotopic ossification was administered reports a rate of heterotopic ossification as high as 82%. We administered indomethacin to all of our patients and we believe it has drastically lowered the rate of heterotopic ossification. Indomethacin is believed to decrease the rate of this complication to about 30-45%.
Femoral head osteonecrosis was recorded in one patient (2%), who subsequently underwent a total hip replacement. Matta 8 reports a rate of femoral head osteonecrosis of 3%, while Moed 14 brings it up to 7%. Post-traumatic osteoarthritis was recorded in 12 patients (24%) of whom 7 underwent a total hip replacement. This rate of post-traumatic osteoarthritis is considered quite satisfactory, in view of the fact that rates of 20-55% are reported in the literature [4,7,8,10,14,17]. The presence of posterior dislocation of the hip, a chondral lesion of the femoral head or the acetabulum, failure to obtain anatomical reduction and complex as opposed to simple fractures are thought to be the main predisposing factors for the advent of post-traumatic osteoarthritis and femoral head osteonecrosis.
In conclusion, we believe that surgical treatment of acetabular fractures leads to a satisfactory outcome, provided the operation is carried out by an experienced surgeon within the first few days following the initial injury and anatomic reduction of the fracture is achieved.

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