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Minimal Surgical Approach for Recurrent Hip Dislocation Using the Posterior Lip Augmentation Device for the Charnley Hip Arthroplasty
The Journal of Arthroplasty Vol. 21 No. 6 2006
Minimal Surgical Approach for Recurrent Hip Dislocation Using the Posterior Lip Augmentation Device for the Charnley Hip Arthroplasty Purushottam A. Gholve, MS, MRCS, Martyn E. Lovell, FRCS (Orth), and S. Zafar Naqui, BSc, MRCS Abstract: We present the management of recurrent posterior dislocations in cemented Charnley total hip arthroplasties treated with acetabular augmentation. Certain patients are elderly with comorbid conditions and diminished reserves. We have used a minimal surgical approach to implant 21 posterior lip augmentation devices in elderly patients. Ninety percent of the hips are stable with follow-up of 1 to 3 years (mean, 1.9 years). Eighty-four percent of the patients were satisfied with the outcome. Two cases, which redislocated, were further stabilized by changing the position of the posterior lip augmentation device and are stable. Because of a minimal surgical approach, the time duration of surgery, blood loss, transfusion requirement, inpatient stay, and morbidity are reduced. Posterior lip augmentation device surgery with a minimal approach is a safe and effective procedure for elderly patients who do not have any obvious cause for dislocation. Key words: minimal surgical approach, hip dislocation, augmentation. n 2006 Elsevier Inc. All rights reserved.
reported with variable success. We describe our experience with a minimal surgical approach after the treatment of 21 recurrent posterior dislocations with the PLAD.
Dislocation after total hip arthroplasty continues to be one of the leading complications. The reported incidence is 0.5% to 9% [1] after primary hip arthroplasty and can be as high as 26% [2] after revision surgery. Certain members of this group are from an elderly population, and it has been shown that there is a cumulative increase in the incidence of dislocation over time with the Charnley prosthesis [3]. Minimal intervention surgery that prevents further dislocation should be the preferred method of management. Augmentation of acetabular cups with the posterior lip augmentation device (PLAD) (Depuy, Leeds, England) has been
Patients and Methods Twenty-five revisions for dislocation were performed between June 2000 and June 2002, including 21 which were treated only with a PLAD. Most of these cases were operated as emergencies (80%), the others as scheduled cases after a closed manipulation had taken place. The operation was performed either by the senior author or by a trainee under supervision. There were 13 women and 8 men with an average age of 76 years (range, 62-88 years). The average number of dislocations before surgery was 4 (range, 2-6). Seventeen of the hips were primary total hip arthroplasties and 4 dislocations were after revision. The average time from first surgery was 6 years (range, 1-12 years) before presentation. All implants were Charnley design with a cemented cup and stem using a 22-mm
From the Department of Trauma and Orthopaedics, South Manchester University Hospitals, Wythenshawe Hospital, Wythenshawe, Manchester, UK. Submitted June 26, 2003; accepted October 21, 2005. No benefits or funds were received in support of this study. Reprint requests: Martyn E. Lovell, FRCS (Orth), South Manchester University Hospitals, Southmoor Road, Wythenshawe Hospital, Wythenshawe, M23 9LT Manchester, UK. n 2006 Elsevier Inc. All rights reserved 0883-5403/06/1906-0004$32.00/0 doi:10.1016/j.arth.2005.10.023
865
866 The Journal of Arthroplasty Vol. 21 No. 6 September 2006 femoral head. Fifteen were previously operated through a lateral approach (13 trochanteric osteotomies [all un-united], 2 Hardinge-type approaches) and 6 were through a posterior approach. The indication for PLAD was any hip that did not have any gross malalignment, wear, or loosening of the primary components (8 had zone 1 cup demarcation). All were consented not only for PLAD, but also for exploration of the hip with possible revision. Description of PLAD The device consists of 2 components, an ultrahigh molecular polyethylene segment that is backed by stainless steel plate. Both these parts have predrilled symmetrical holes and an inner curvature, which is congruent with the femoral head prosthesis. The PLAD is much higher or thicker than the usual raised posterior wall of the standard long posterior walled cup (Fig. 1). Minimal Surgical Approach The patient is placed in the lateral position supported by side supports. An 8-cm incision is made centered over the greater trochanter through the previous surgical scar (irrespective of the previous approach being lateral or posterior). The incision is deepened by dividing the iliotibial band and gluteal fascia, and any stuck-down fibers of gluteus medius are mobilized by blunt dissection. The greater trochanteric bursa, if present, is excised. A small self-retaining retractor is used to keep the tissues retracted. Examination of the hip is performed by internal rotation of femur to feel the femoral prosthetic head below the external rotators as dislocation occurs. A longitudinal incision is made over the external rotators just over the palpable head. The prosthetic head is exposed, then
Fig. 1. PLAD and screws.
Fig. 2. Operative view of PLAD applied.
relocated; a Hohmann retractor is placed in the obturator foramen. Posterior capsular tissue and pseudomembrane needs to be excised with rongeurs to allow visualization, and bone does not need to be removed. The placement of Hohmann retractor allows adequate exposure of the acetabular cup. The cup is examined for wear; it can be fully examined by distracting the femoral prosthesis with a dislocation hook. In presence of wear we would proceed with revision of the cup and increase our exposure abandoning the minimal exposure (this has not been necessary). In absence of wear we reduce the hip and observe the zone from where the head is dislocating. On confirmation of the zone, which was always posterior neutral or inferior (this was often confirmed by roughening of the posterior rim polyethylene), the PLAD is placed congruently posteriorly over the cup and fixed with five 4.5 25 mm cortical screws (Fig. 2). The screws pass through the cup and the cement and enter the bone (Figs. 3 and 4). If the augment is placed congruently at the back wall of the cup, the screw holes are centralized in the polyethylene, thus making articular surface penetration very unlikely unless the screws were drilled in a very angulated fashion. The hip is examined for stability and impingement of the neck is ruled out; levering forward of the hip to cause it to come out of the front does not appear to occur by the built-up back wall. A successful result would appear to be achieved by building up the back wall of the cup to stop the head lifting out of the back. The external rotators and capsule are repaired with interrupted stitches, and the wound is closed in a standard way. All the patients are mobilized full weight-bearing on day 1 after surgery either with a frame or crutches.
Augmentation for Recurrent Hip Dislocation ! Gholve et al 867
Description of Clinical and Radiologic Methods All patients were followed up at 6 weeks, 6 months, and 1 year and on an annual basis. Clinical and radiologic assessments by frontal and lateral views were performed at each visit. Information was obtained from the case notes, theater records, anesthetic notes, nursing records, and a postal questionnaire. Oxford hip scores were unfortunately only used preoperatively for 6 patients, but the patients were also asked whether they were very satisfied, satisfied, or unsatisfied.
Results Of the total 21 hips, 19 (90%) remained stable, at least by 1-3 years postoperatively (mean, 1.9 years). The 2 hips, which dislocated, were explored, and the PLAD position was changed further to cover the head. (Four screws were removed and the PLAD rotated forward to partially cover the head, the 4 screws were then reapplied. It is estimated that the last screw hole moved forward 4-5 mm.) These hips have subsequently remained in joint at 10 months postoperatively. Duration of surgery was a mean of 41 minutes from incision to closure; operative blood loss was a mean of 130 mL (range, 80-280 mL); no patients were transfused; the mean hospital stay was 4 days (range, 3-8 days).
Fig. 4. Lateral x-ray of same hip.
None of the hips show any radiologic evidence of component loosening or screw breakage. Two cases, which had a superficial infection, settled on oral antibiotics without incident, and the patients’ discharge from hospital was not delayed; culture swabs grew skin commensals. Two patients have persistent pain while walking, for reasons that were ill defined. We could not attribute this to any aspects of our surgery. Eighty-four percent of patients were very satisfied with the outcome, and 16% were unsatisfied. Oxford scores only changed to the positive by 1 to 2 points, with slight improvements in function (range, 38-40). Most patients seemed somewhat cautious. We did not encourage them to overstrain their augmented hip, which did not seem problematic in a group that we would describe as low demand. The 5 trainees who had performed this surgery under supervision were satisfied with the ease and exposure they achieved through this approach.
Discussion
Fig. 3. Anteroposterior x-ray of an applied PLAD in a hip replacement that dislocated at 5 years.
Recurrent dislocation of a total hip arthroplasty is a difficult problem with multifactorial etiology. Most patients were very happy with their hip arthroplasty for some years before this problem occurred. It would appear that our success is because of posterior wall build-up. Cup anteversion may have had similar results, although no gross abnormality was found, but we are aware of high
868 The Journal of Arthroplasty Vol. 21 No. 6 September 2006 rates of recurrence of dislocation when this is tried [4], possibly because of greater dissection. There were 13 un-united trochanters, which resulted in abductor insufficiency. Revision arthroplasty [5] for recurrent dislocations is performed for different indications. We now choose to perform PLAD surgery as our index procedure for any older, low-demand patient, but would acknowledge that others will have success with component repositioning, femoral lengthening to adjust soft tissue tension, capture cups, and trochanteric reattachments or advancements. These patients cannot be treated nonoperatively as they have a severely restricted lifestyle because of their hip instability. An offer of augmentation is made after the second or third dislocation. We do not assess the degree of instability under anesthesia or radiologically before this decision is made. Acetabular augmentation was first described by Olerud and Karlstrom [6] with variable success. Since then, Madan et al [7] have reported a series of 68 cases of the Wroblewski wedge with a success of 76%, and Charlwood et al [5] have a series of 20 cases with success of 100%. Both of these reports suggest that all of the previous operations were done through a posterior approach. Nicholl et al [8] used a lateral approach with a trochanteric osteotomy in 5 of the 28 hips they treated. In our view, a very wide exposure or trochanteric osteotomy is not essential to augment the cup with a PLAD. The advantage of the approach that we use is that it requires minimal skin incision and it does not matter which approach was used previously. Minimal surgical time, less blood loss, minimal inpatient stay, and reduced morbidity are its quoted advantages [5]. One disadvantage with the PLAD is that it cannot be used for any cup that has a metal backing. All of our patients were elderly or very low demand, and this procedure would not be ideal in younger or high-demand patients where the risk of cup loosening would be high. Gungor and Hallin [9] and Williamson et al [10] have reported screw breakage, but so far in our series we have none. Screw breakage is indicator of possible impingement and abnormal stresses on the device, although the authors did state that they tried to avoid impingement on placement of the PLAD. They stated after screw breakage that the patients were asymptomatic and screw breakage does not have any short-term effects. One of the criticisms of neck impingement by this augment is that it could cause further dislocation [11,12]. We have not had any complications of neck impingement. On the contrary, the 2 cases that were reexplored for further dislocation had their PLAD
placed in a covering position, which in principle covers the head further and is very close to the neck. These hips have not further dislocated for the last 10 months. We conclude that the PLAD with a minimal surgical approach is a very good solution for recurrent posterior total hip dislocations in the elderly. The mean operative time, blood loss, and inpatient stay are unmatched by any but the simplest procedures that might include head or plastic liner exchange and perhaps trochanteric transfer [5].
References 1. Paterno SA, Lachiewicz PF, Kelley SS. The influence of patient related factors and the position of the acetabular component on the rate of dislocation after total hip replacement. J Bone Joint Surg 1997; 79A:1202. 2. Grigoris P, Grecula MJ, Amstutz HC. Tripolar hip replacement for recurrent prosthetic dislocation. Clin Orthop 1994;304:148. 3. Berry DJ, von Knoch M, Schleck CD, et al. The cumulative long-term results of dislocation after primary Charnley total hip arthroplasty. J Bone Joint Surg 2004;86A:9. 4. Daly PJ, Morrey BF. Operative correction of an unstable total hip arthroplasty. J Bone Joint Surg 1992;74A:1334. 5. Charlwood AP, Thompson NW, Thompson NS, et al. Recurrent hip arthroplasty dislocation; Good outcome after cup augmentation in 20 patients followed for 2 years. Acta Orthop Scand 2002; 73:502. 6. Olerud S, Karlstrom G. Recurrent dislocation after total hip replacement. Treatment by fixing an additional sector to the acetabular component. J Bone Joint Surg Br 1985;67:402. 7. Madan S, Sekhar S, Fiddian NJ. Wroblewski wedge augmentation for recurrent posterior dislocation of the Charnley total hip replacement. Ann R Coll Surg Eng 2002;84:399. 8. Nicholl JE, Koka SR, Blintcliffe IW, et al. Acetabular augmentation for the treatment of unstable total hip arthroplasties. Ann R Coll Surg Eng 1999;81:127. 9. Gungor T, Hallin G. Cup reinforcement for recurrent dislocation after hip replacement. J Bone Joint Surg Br 1990;72:525. 10. Williamson JB, Galasko CSB, Rowley DI. Failure of acetabular augmentation for recurrent dislocation after hip arthroplasty. A report of 3 cases. Acta Orthop Scand 1989;60:676. 11. Gie GA, Scott TD, Ling RSM. Cup augmentation for recurrent hip replacement dislocation. J Bone Joint Surg Br 1989;71:38. 12. Graham GP, Jenkins AIR, Mintowt-Czyz W. Recurrent dislocation following hip replacement: brief report. J Bone Joint Surg Br 1988;70:675.
Minimal Surgical Approach for Recurrent Hip Dislocation Using the Posterior Lip Augmentation Device for the Charnley Hip Arthroplasty Purushottam A. Gholve, MS, MRCS, Martyn E. Lovell, FRCS (Orth), and S. Zafar Naqui, BSc, MRCS Abstract: We present the management of recurrent posterior dislocations in cemented Charnley total hip arthroplasties treated with acetabular augmentation. Certain patients are elderly with comorbid conditions and diminished reserves. We have used a minimal surgical approach to implant 21 posterior lip augmentation devices in elderly patients. Ninety percent of the hips are stable with follow-up of 1 to 3 years (mean, 1.9 years). Eighty-four percent of the patients were satisfied with the outcome. Two cases, which redislocated, were further stabilized by changing the position of the posterior lip augmentation device and are stable. Because of a minimal surgical approach, the time duration of surgery, blood loss, transfusion requirement, inpatient stay, and morbidity are reduced. Posterior lip augmentation device surgery with a minimal approach is a safe and effective procedure for elderly patients who do not have any obvious cause for dislocation. Key words: minimal surgical approach, hip dislocation, augmentation. n 2006 Elsevier Inc. All rights reserved.
reported with variable success. We describe our experience with a minimal surgical approach after the treatment of 21 recurrent posterior dislocations with the PLAD.
Dislocation after total hip arthroplasty continues to be one of the leading complications. The reported incidence is 0.5% to 9% [1] after primary hip arthroplasty and can be as high as 26% [2] after revision surgery. Certain members of this group are from an elderly population, and it has been shown that there is a cumulative increase in the incidence of dislocation over time with the Charnley prosthesis [3]. Minimal intervention surgery that prevents further dislocation should be the preferred method of management. Augmentation of acetabular cups with the posterior lip augmentation device (PLAD) (Depuy, Leeds, England) has been
Patients and Methods Twenty-five revisions for dislocation were performed between June 2000 and June 2002, including 21 which were treated only with a PLAD. Most of these cases were operated as emergencies (80%), the others as scheduled cases after a closed manipulation had taken place. The operation was performed either by the senior author or by a trainee under supervision. There were 13 women and 8 men with an average age of 76 years (range, 62-88 years). The average number of dislocations before surgery was 4 (range, 2-6). Seventeen of the hips were primary total hip arthroplasties and 4 dislocations were after revision. The average time from first surgery was 6 years (range, 1-12 years) before presentation. All implants were Charnley design with a cemented cup and stem using a 22-mm
From the Department of Trauma and Orthopaedics, South Manchester University Hospitals, Wythenshawe Hospital, Wythenshawe, Manchester, UK. Submitted June 26, 2003; accepted October 21, 2005. No benefits or funds were received in support of this study. Reprint requests: Martyn E. Lovell, FRCS (Orth), South Manchester University Hospitals, Southmoor Road, Wythenshawe Hospital, Wythenshawe, M23 9LT Manchester, UK. n 2006 Elsevier Inc. All rights reserved 0883-5403/06/1906-0004$32.00/0 doi:10.1016/j.arth.2005.10.023
865
866 The Journal of Arthroplasty Vol. 21 No. 6 September 2006 femoral head. Fifteen were previously operated through a lateral approach (13 trochanteric osteotomies [all un-united], 2 Hardinge-type approaches) and 6 were through a posterior approach. The indication for PLAD was any hip that did not have any gross malalignment, wear, or loosening of the primary components (8 had zone 1 cup demarcation). All were consented not only for PLAD, but also for exploration of the hip with possible revision. Description of PLAD The device consists of 2 components, an ultrahigh molecular polyethylene segment that is backed by stainless steel plate. Both these parts have predrilled symmetrical holes and an inner curvature, which is congruent with the femoral head prosthesis. The PLAD is much higher or thicker than the usual raised posterior wall of the standard long posterior walled cup (Fig. 1). Minimal Surgical Approach The patient is placed in the lateral position supported by side supports. An 8-cm incision is made centered over the greater trochanter through the previous surgical scar (irrespective of the previous approach being lateral or posterior). The incision is deepened by dividing the iliotibial band and gluteal fascia, and any stuck-down fibers of gluteus medius are mobilized by blunt dissection. The greater trochanteric bursa, if present, is excised. A small self-retaining retractor is used to keep the tissues retracted. Examination of the hip is performed by internal rotation of femur to feel the femoral prosthetic head below the external rotators as dislocation occurs. A longitudinal incision is made over the external rotators just over the palpable head. The prosthetic head is exposed, then
Fig. 1. PLAD and screws.
Fig. 2. Operative view of PLAD applied.
relocated; a Hohmann retractor is placed in the obturator foramen. Posterior capsular tissue and pseudomembrane needs to be excised with rongeurs to allow visualization, and bone does not need to be removed. The placement of Hohmann retractor allows adequate exposure of the acetabular cup. The cup is examined for wear; it can be fully examined by distracting the femoral prosthesis with a dislocation hook. In presence of wear we would proceed with revision of the cup and increase our exposure abandoning the minimal exposure (this has not been necessary). In absence of wear we reduce the hip and observe the zone from where the head is dislocating. On confirmation of the zone, which was always posterior neutral or inferior (this was often confirmed by roughening of the posterior rim polyethylene), the PLAD is placed congruently posteriorly over the cup and fixed with five 4.5 25 mm cortical screws (Fig. 2). The screws pass through the cup and the cement and enter the bone (Figs. 3 and 4). If the augment is placed congruently at the back wall of the cup, the screw holes are centralized in the polyethylene, thus making articular surface penetration very unlikely unless the screws were drilled in a very angulated fashion. The hip is examined for stability and impingement of the neck is ruled out; levering forward of the hip to cause it to come out of the front does not appear to occur by the built-up back wall. A successful result would appear to be achieved by building up the back wall of the cup to stop the head lifting out of the back. The external rotators and capsule are repaired with interrupted stitches, and the wound is closed in a standard way. All the patients are mobilized full weight-bearing on day 1 after surgery either with a frame or crutches.
Augmentation for Recurrent Hip Dislocation ! Gholve et al 867
Description of Clinical and Radiologic Methods All patients were followed up at 6 weeks, 6 months, and 1 year and on an annual basis. Clinical and radiologic assessments by frontal and lateral views were performed at each visit. Information was obtained from the case notes, theater records, anesthetic notes, nursing records, and a postal questionnaire. Oxford hip scores were unfortunately only used preoperatively for 6 patients, but the patients were also asked whether they were very satisfied, satisfied, or unsatisfied.
Results Of the total 21 hips, 19 (90%) remained stable, at least by 1-3 years postoperatively (mean, 1.9 years). The 2 hips, which dislocated, were explored, and the PLAD position was changed further to cover the head. (Four screws were removed and the PLAD rotated forward to partially cover the head, the 4 screws were then reapplied. It is estimated that the last screw hole moved forward 4-5 mm.) These hips have subsequently remained in joint at 10 months postoperatively. Duration of surgery was a mean of 41 minutes from incision to closure; operative blood loss was a mean of 130 mL (range, 80-280 mL); no patients were transfused; the mean hospital stay was 4 days (range, 3-8 days).
Fig. 4. Lateral x-ray of same hip.
None of the hips show any radiologic evidence of component loosening or screw breakage. Two cases, which had a superficial infection, settled on oral antibiotics without incident, and the patients’ discharge from hospital was not delayed; culture swabs grew skin commensals. Two patients have persistent pain while walking, for reasons that were ill defined. We could not attribute this to any aspects of our surgery. Eighty-four percent of patients were very satisfied with the outcome, and 16% were unsatisfied. Oxford scores only changed to the positive by 1 to 2 points, with slight improvements in function (range, 38-40). Most patients seemed somewhat cautious. We did not encourage them to overstrain their augmented hip, which did not seem problematic in a group that we would describe as low demand. The 5 trainees who had performed this surgery under supervision were satisfied with the ease and exposure they achieved through this approach.
Discussion
Fig. 3. Anteroposterior x-ray of an applied PLAD in a hip replacement that dislocated at 5 years.
Recurrent dislocation of a total hip arthroplasty is a difficult problem with multifactorial etiology. Most patients were very happy with their hip arthroplasty for some years before this problem occurred. It would appear that our success is because of posterior wall build-up. Cup anteversion may have had similar results, although no gross abnormality was found, but we are aware of high
868 The Journal of Arthroplasty Vol. 21 No. 6 September 2006 rates of recurrence of dislocation when this is tried [4], possibly because of greater dissection. There were 13 un-united trochanters, which resulted in abductor insufficiency. Revision arthroplasty [5] for recurrent dislocations is performed for different indications. We now choose to perform PLAD surgery as our index procedure for any older, low-demand patient, but would acknowledge that others will have success with component repositioning, femoral lengthening to adjust soft tissue tension, capture cups, and trochanteric reattachments or advancements. These patients cannot be treated nonoperatively as they have a severely restricted lifestyle because of their hip instability. An offer of augmentation is made after the second or third dislocation. We do not assess the degree of instability under anesthesia or radiologically before this decision is made. Acetabular augmentation was first described by Olerud and Karlstrom [6] with variable success. Since then, Madan et al [7] have reported a series of 68 cases of the Wroblewski wedge with a success of 76%, and Charlwood et al [5] have a series of 20 cases with success of 100%. Both of these reports suggest that all of the previous operations were done through a posterior approach. Nicholl et al [8] used a lateral approach with a trochanteric osteotomy in 5 of the 28 hips they treated. In our view, a very wide exposure or trochanteric osteotomy is not essential to augment the cup with a PLAD. The advantage of the approach that we use is that it requires minimal skin incision and it does not matter which approach was used previously. Minimal surgical time, less blood loss, minimal inpatient stay, and reduced morbidity are its quoted advantages [5]. One disadvantage with the PLAD is that it cannot be used for any cup that has a metal backing. All of our patients were elderly or very low demand, and this procedure would not be ideal in younger or high-demand patients where the risk of cup loosening would be high. Gungor and Hallin [9] and Williamson et al [10] have reported screw breakage, but so far in our series we have none. Screw breakage is indicator of possible impingement and abnormal stresses on the device, although the authors did state that they tried to avoid impingement on placement of the PLAD. They stated after screw breakage that the patients were asymptomatic and screw breakage does not have any short-term effects. One of the criticisms of neck impingement by this augment is that it could cause further dislocation [11,12]. We have not had any complications of neck impingement. On the contrary, the 2 cases that were reexplored for further dislocation had their PLAD
placed in a covering position, which in principle covers the head further and is very close to the neck. These hips have not further dislocated for the last 10 months. We conclude that the PLAD with a minimal surgical approach is a very good solution for recurrent posterior total hip dislocations in the elderly. The mean operative time, blood loss, and inpatient stay are unmatched by any but the simplest procedures that might include head or plastic liner exchange and perhaps trochanteric transfer [5].
References 1. Paterno SA, Lachiewicz PF, Kelley SS. The influence of patient related factors and the position of the acetabular component on the rate of dislocation after total hip replacement. J Bone Joint Surg 1997; 79A:1202. 2. Grigoris P, Grecula MJ, Amstutz HC. Tripolar hip replacement for recurrent prosthetic dislocation. Clin Orthop 1994;304:148. 3. Berry DJ, von Knoch M, Schleck CD, et al. The cumulative long-term results of dislocation after primary Charnley total hip arthroplasty. J Bone Joint Surg 2004;86A:9. 4. Daly PJ, Morrey BF. Operative correction of an unstable total hip arthroplasty. J Bone Joint Surg 1992;74A:1334. 5. Charlwood AP, Thompson NW, Thompson NS, et al. Recurrent hip arthroplasty dislocation; Good outcome after cup augmentation in 20 patients followed for 2 years. Acta Orthop Scand 2002; 73:502. 6. Olerud S, Karlstrom G. Recurrent dislocation after total hip replacement. Treatment by fixing an additional sector to the acetabular component. J Bone Joint Surg Br 1985;67:402. 7. Madan S, Sekhar S, Fiddian NJ. Wroblewski wedge augmentation for recurrent posterior dislocation of the Charnley total hip replacement. Ann R Coll Surg Eng 2002;84:399. 8. Nicholl JE, Koka SR, Blintcliffe IW, et al. Acetabular augmentation for the treatment of unstable total hip arthroplasties. Ann R Coll Surg Eng 1999;81:127. 9. Gungor T, Hallin G. Cup reinforcement for recurrent dislocation after hip replacement. J Bone Joint Surg Br 1990;72:525. 10. Williamson JB, Galasko CSB, Rowley DI. Failure of acetabular augmentation for recurrent dislocation after hip arthroplasty. A report of 3 cases. Acta Orthop Scand 1989;60:676. 11. Gie GA, Scott TD, Ling RSM. Cup augmentation for recurrent hip replacement dislocation. J Bone Joint Surg Br 1989;71:38. 12. Graham GP, Jenkins AIR, Mintowt-Czyz W. Recurrent dislocation following hip replacement: brief report. J Bone Joint Surg Br 1988;70:675.