Cementless acetabular reconstruction and structural bone-grafting in dysplastic hips

Minimum 10-year Survivorship of Uncemented Acetabular Reconstruction with Bulk Femoral Head Autografting in Crowe Type IV Developmental Hip Dysplasia

BACKGROUND

In total hip arthroplasty (THA) for severe dislocations such as Crowe type IV developmental dysplasia of the hip (DDH), sufficient bone volume for stable fixation of the acetabular component can be achieved by placing a reinforcing bone graft prepared from the resected femoral head into the deficient acetabulum. The purpose of the current study was to examine the long-term survivorship of uncemented THA in conjunction with a bulk femoral head autograft in patients who have Crowe type IV DDH.

METHODS

A total of 35 patients (42 hips) who have Crowe type IV DDH and underwent THA using uncemented cup fixation with bulk femoral head autografting were followed up for a mean period of 15.0 years (range, 10.0 to 20.0) postoperatively. Anteroposterior pelvic radiographs were used for measurements such as the horizontal coverage of the grafted bone and the center-edge angle. Kaplan-Meier survivorship analyses were performed with revision of the acetabular component as the endpoint.

RESULTS

The Kaplan-Meier analysis indicated 15-year survival rates of 90.4%. The mean horizontal coverage of grafted bone was 46.1% (range, 23.7 to 66.0), and there were 16 cases with horizontal coverage of ≥ 50%. There was no difference in the appearance of a thin (< 1 mm) radiolucency line around the cup between cases with < 50% versus ≥ 50% of the horizontal coverage of grafted bone (4 versus 2 hips; P = 0.446). Trabecular bridging and remodeling were seen in all cases after mean periods of 4.1 months and 9.0 months postoperatively, respectively. Trabecular reorientation was seen in 41 of 42 hips (97.6%) at a mean follow-up of 19.9 months.

CONCLUSIONS

Acetabular reconstruction with femoral bulk bone grafting for Crowe type IV DDH resulted in high survival rates and was a good method to restore bone stock and obtain long-term fixation.

Mean 14-year Outcomes of Hybrid Total Hip Arthroplasty Using Bulk Femoral Head Autografts for Acetabular Reconstruction

BACKGROUND

We aimed to evaluate the mean 14-year outcomes of hybrid total hip arthroplasty (THA) with cementless acetabular cups using bulk femoral head autografts in acetabular reconstruction and specify the radiological characteristics of cementless acetabular cups using this technique.

METHODS

This retrospective study included 98 patients (123 hips) who underwent hybrid THA with a cementless acetabular cup using bulk femoral head autografts for bone deficiency in acetabular dysplasia and who were followed-up for a mean of 14 years (range, 10 to 19.6). The percentage of bone coverage index (BCI) and cup center-edge (CE) angles were evaluation radiologically of acetabular host bone coverage. The survival rate of the cementless acetabular cup and autograft bone ingrowth were assessed.

RESULTS

The survival rate with all revisions of cementless acetabular cups was 97.1% (95% confidence interval: 91.2 to 99.1). The autograft bone was remodeled or reoriented in all cases except in 2 hips where the bulk femoral head autograft collapsed. Radiological evaluation revealed a mean cup CE angle of -17.8° (range, -52 to -7°) and a BCI of 44.4% (range, 10 to 75.4%).

CONCLUSION

Cementless acetabular cups using bulk femoral head autografts for bone deficiency of the acetabular roof remained stable even if the average BCI was 44.4% and the average cup CE angle was -17.8°. Cementless acetabular cups using these techniques showed good 10-year to 19.6-year outcomes and viabilities of graft bones.

Femoral head and neck autograft in arthroplasty for developmental dysplasia of the hip: a systematic review of long-term outcomes

PURPOSE

Total hip arthroplasty (THA) with an acetabular component and an autogenous femoral head graft for acetabular reconstruction in developmental dysplasia of the hip was first described by Harris et al. in 1977. While a number of studies have addressed the aforementioned scenario over the last decades, most lack sufficient numbers and follow-up. As such, we analyzed long-term outcomes of THAs with femoral autograft for arthrosis secondary to hip dysplasia.

METHODS

A systematic review was performed using a structured PubMed, Web of Science, Ovid MEDLINE, and Cochrane analysis, based on the PRISMA criteria. All original studies from 1977 to 2022 with a mean follow-up of 10 or more years were included. Methodological Index for Nonrandomized Studies (MINORS) were used for quality assessment.

RESULTS

A total of 26 studies with 1316 patients (87% females) undergoing 1543 THAs with femoral autograft (2 times neck graft, 24 times head graft) were included. Mean age was 52 years (range, 28-73) and the mean follow-up was 13 years (range, 9-18). The revision rate was 8.3% (n = 129), and 73% of revisions were for loosening. Rate of infection (0.5%) and dislocations (1%) were low. Radiographic analysis revealed 167 loose acetabular components (11%) and 118 cases of graft resorption (7.6%). Mean Harris Hip Score increased from 42 to 85. Mean MINORS score was 11, and no study was level of evidence I or II.

CONCLUSIONS

Femoral autograft with THA may be a viable long-term option for hip reconstruction in developmental dysplasia of the hip. However, moderate loosening rates and low level of evidence must be acknowledged before drawing the final conclusions.

LEVEL OF EVIDENCE

Therapeutic Level III.

Impaction Grafting Is Sufficient to Address Acetabular Deficiency During Total Hip Arthroplasty of Most Dysplastic Hips With Over 30% Bone Defect

BACKGROUND

Addressing acetabular deficiency during arthroplasty of dysplastic hips is challenging. We assessed outcomes of a protocol for choosing either impaction or structural graft for this purpose.

METHODS

This retrospective study included 59 patients (71 hips) with a dysplastic hip and over 30% uncoverage that underwent cementless total hip arthroplasty. Morselized impaction grafting was performed for hips where initial stability of the acetabular cup was achieved. In others, a shelf graft was inserted before implantation of the acetabular cup. Outcomes were assessed at a minimum follow-up of 4 years.

RESULTS

Fifty-seven (80.3%) hips underwent impaction grafting and 14 (19.7%) received a structural graft. Mean age at surgery was 48.1 ± 13.5 (18-68) years for impaction and 48.6 ± 14 (24-70) years for shelf grafts. Mean increase in Harris Hip Score was 51.5 ± 9.3 and 50 ± 11.2 for the impaction and structural groups, respectively, at a mean follow-up of 92 (49-136) months (P = .6). Heterotopic ossification occurred in 16 patients in the impaction group vs none in the structural group (P = .004). Radiologically, mean percentages of cup coverage provided by the graft were 47.8 ± 10.9% and 48.9 ± 13.3% in the impaction and structural groups, respectively (P = .75). All but one of shelf grafts united to host bone and all impaction grafts incorporated. There was one case of cup loosening in the structural graft group.

CONCLUSION

Most dysplastic acetabula with over 30% defect can be addressed using a cementless cup and impaction grafting, with good results in the midterm. In about 20% of cases, initial press-fit is not attainable and structural support-like shelf graft becomes necessary.

LEVEL OF EVIDENCE

IV.

Anatomic acetabular reconstruction with femoral head autograft for developmental dysplasia of the hip (DDH) with a minimum follow-up of 10 years

BACKGROUND

DDH with coxarthrosis causes significant deformity and bone deficiency. Various reconstructive techniques have been proposed to treat developmental dysplasia of the hip. However, the existing literature has not yet reached a consensus on the best technique regarding long-term survival.

OBJECTIVES

This study aims to evaluate the long-term survival of uncemented hydroxyapatite (HA) coated acetabular components augmented with a femoral head autograft.

METHODS

We retrospectively reviewed the cases of 31 hips in 29 patients (24 female, 5 male, mean age 45.06 years) treated with HA-coated cementless components and femoral head autograft between 2000-2008 with a minimum follow-up of 10 years. Graft resorption, cup loosening and the anatomical hip centre were determined. Functional outcomes were calculated using the Harris Hip Scoring system. The survival of the acetabular component was evaluated using the Kaplan-Meier method.

RESULTS

In 24 hips (77,4%), we reconstructed the hip centre anatomically. The remaining cups had variable deviations from the anatomical rotation centre. Only one patient required revision due to loosening. Survival analysis revealed 96.8% survival at 10 years. The mean Harris Hip Score was 39.23 preoperatively and 84.77 at final follow-up. There was no statistical correlation between revision and any of the measured parameters.

DISCUSSION

Acetabular reconstruction with a femoral head autograft allows for anatomical cup positioning, early structural support and increases bone stock for future revisions. Although our prior cemented cup study showed that anatomical cup orientation is critical, this study demonstrated the absence of a correlation between implant failure and cup positioning, suggesting that HA-coated cementless cups are more stable and forgiving.

CONCLUSIONS

HA-coated acetabular cups augmented with femoral head autograft provided long-term, reliable and durable cup fixation in dysplastic hips of young adults.

Functional and radiographical results of asymmetrically reconstructed total hip arthroplasty in patients with bilateral dysplastic arthritic hips with one hip Crowe II-III and the other Crowe IV: a retrospective cohort study

Background

The study aimed to evaluate the functional and radiographical results of asymmetrically reconstructed total hip arthroplasty in patients with bilateral dysplastic arthritic hips with one hip Crowe II–III and the other hip Crowe IV.

Materials and methods

From April 2006 to April 2019, we evaluated 23 patients who had a reconstruction of one Crowe II–III hip with high hip center (HHC) and the other Crowe IV hip at the anatomical position (H group). The radiographic and clinical outcomes were compared with those of a control group of 19 patients with bilateral dysplasia who had one Crowe IV hip and the contralateral hip both reconstructed in the anatomical position (A group). Medical records and radiographs were reviewed, and a complete follow-up was conducted for all patients.

Results

The mean vertical center of rotation (V-COR) and horizontal center of rotation (H-COR) in the H group were 30.6 ± 5.8 mm and 30.0 ± 5.5 mm, respectively. In the A group, the corresponding values were 14.0 ± 4.3 mm and 23.0 ± 2.3 mm, respectively. A significant difference was found in terms of V-COR and H-COR between the two groups, and no significant difference was shown regarding the cup inclination, abductor lever arm (ALA), ALA ratio, and leg length discrepancy (LLD). Three patients of the H group and four patients of the A group exhibited LLD > 10 mm. All seven patients who had LLD > 10 mm underwent the shortening subtrochanteric osteotomy (SSTO) of the Crowe IV hip. Subgroup analysis based on the presence and absence of SSTO showed that the LLD of the SSTO group was greater than that of the non-SSTO group in both groups, but the difference was only statistically significant in the A group. At the last follow-up, the mean Harris Hip Scores significantly improved in the two groups, and there was no revision during the follow-up period. In the H group, four patients presented with a slight limp and three patients with a moderate limp, while it was six patients and one patient in the A group, respectively.

Conclusions

Asymmetrical reconstruction in patients with bilateral dysplastic arthritic hips with one hip Crowe II–III and the other Crowe IV is acceptable and comparable when compared with bilateral anatomical reconstruction.

Level of evidence

III, retrospective observational study.

Trial registration Chinese Clinical Trail Registry. ChiCTR2000033848

Stepped osteotomy of femoral head autograft for acetabular reconstruction in total hip arthroplasty for dysplasia of the hip: 3 to 12 years' results

OBJECTIVES

This study aims to describe a stepped osteotomy technique applied to the femoral head autograft to keep the graft volume at a sufficient level, provide primary stability, and direct cancellous-cancellous bone contact.

PATIENTS AND METHODS

In this retrospective study, 24 hips of 20 patients (5 males, 15 females; mean age 53 years; range, 43 to 68 years) with dysplasia of the hip (DDH) who underwent total hip arthroplasty with femoral head stepped osteotomy technique were evaluated between April 2003 and June 2010. Patients' age, gender, operation side, and postoperative complications were recorded. Aseptic loosening of the acetabular cup and graft integration/resorption were evaluated radiographically. Radiological evaluations were performed according to the methods of DeLee and Charnley, and Mulroy and Harris. Functional status of the patients was determined according to the criteria of Merle d'Aubigné and Postel, and Harris hip score (HHS).

RESULTS

The mean follow-up period was 5.5 years (range, 3 to 12 years). None of the patients had any complications in the early postoperative period. In all patients, the percentage of acetabular component coverage by the graft was measured as 27% (range, 19 to 38%) on average. At the last follow-up, all patients were satisfied with the result and there was no sign of clinically loosening, osteointegration was complete, and there was no radiographic evidence of graft resorption or collapse of any hip. The overall Merle d'Aubigné scores and HHSs of the patients significantly improved at the final follow-up.

CONCLUSION

This stepped osteotomy technique increases the probability of osteointegration, reduces the need for early revision, and provides reliable stability with satisfactory clinical and radiological midterm results.

[Challenges of primary hip arthroplasty with high hip dislocation]

BACKGROUND

Endoprosthetic care of high hip dislocation is a surgical challenge. The hip anatomy is greatly altered in these patients, including a rather flat and small acetabulum with impaired bone quality and a relevant chance of a bony defect of the acetabular roof. Additionally, the front coverage and in some cases even the dorsal coverage of the hip are missing. The proximal femur is characterized with an increased antetorsion, a coxa valga position and an enlarged greater trochanter. The medullary cavity is narrowed, the offset is reduced, and the absolut leg length can be enlarged. Further anatomic variations can have been caused by previous surgeries.

AIM OF THE TREATMENT

The goal of the endoprosthetic care is the re-creation of a hip with an anatomic center of rotation, an anatomic offset and equal leg length.

TREATMENT

This can be achieved by a medial shift of the acetabular cup. An acetabular osteotomy including central cancellous bone graft or a bony graft to reinforce the acetabular roof might be necessary. In cases in which an anatomic acetabular cup placement is not possible, a more cranial placement can be done. Further strategies that are essential in several cases are shortening or re-orientation osteotomies of the femur, reaming of the medullary cavity and correct implant selection. Additionally, thorough soft tissue management is of main importance. Generally, the surgery should be well prepared preoperatively.

Long-term retrospective study on the placement of the cementless acetabular cup and clinical outcomes in patients undergoing femoral head autografting for hip dysplasia and total hip arthroplasty

BACKGROUND

Placement of acetabular cup in the dysplastic hip is a challenging procedure. Using bulk femoral head autograft to increase the bony coverage of the cup is one of the techniques, which have been described. The impact of cup position on cup and autograft survival is a controversial issue. We aimed to determine whether the position of cementless acetabular cup used in conjunction with femoral head autograft in dysplastic hips affected the autograft-host incorporation with its final radiographic appearance and the cup survivorship into the second decade.

METHODS

Thirty-eight dysplastic hips with varying Crowe types in 31 patients (30 women and one man) were included. The mean age was 47 years (range, 29-64 years) and the mean follow-up was 20.3 years (range, 14.8-25.9 years). The initial postoperative and final radiographs were evaluated. The survival rate of the cups was analysed using Kaplan-Meier statistics and the log-rank test. Multivariate analysis was used to evaluate the effect of variables (Crowe type, radiographic initial host bone coverage over the cup and position of the cup) on survivorship.

RESULTS

The acetabular cups were positioned anatomical in 27/38 hips according to Ranawat measurement technique. Trabecular bridging at graft-host interface was seen in all cases at an average 22.1 months. Neither acetabular cup position nor initial host bone coverage over acetabular cup less than 50% had any significant effect on either cup survival or final radiographic appearance of the graft. The 20-year cup survival rate without aseptic revision was 66% (95 CI, 52%-84%). No revision was performed due to graft resorption.

CONCLUSION

Twenty-year survival rate of the cementless cup combination with femoral head autograft showed no significant differences whether it was placed at high or anatomic hip centre. The final radiographic appearance of the autograft was not affected from either the cup location or the initial radiographic horizontal host bone coverage.

Computed Tomographic Evaluation of Bone Stock in Patients With Crowe Type III Developmental Dysplasia of the Hip: Implications for Guiding Acetabular Component Placement Using the High Hip Center Technique

BACKGROUND

We evaluated acetabular cup coverage (CC) and rim contact (RC) to evaluate the bone stock above the acetabulum for guiding acetabular component placement using the high hip center technique in patients with Crowe type III developmental dysplasia of the hip.

METHODS

Using hip computed tomography and image processing software, pelvises were reconstructed digitally in 20 hips with Crowe type III developmental dysplasia of the hip. Mimicked cup was placed with anteversion angles of 0° (group I), 5° (group II), and 10° (group III) respectively. In each group, the cup was placed at the anatomical hip center at first, and then the cup was moved up to 40 mm vertically about the native rotation center with an increment of 2.5 mm at each step. CC and RC were calculated and documented with each movement.

RESULTS

CC was 65.87%, 67.77%, and 68.98% for group I, group II, and group III at the native rotation center, and increased progressively to 86.45%, 85.85%, and 84.71% at 25 mm above. RC was 49.17%, 50.25%, and 51.92% for group I, group II, and group III at the native rotation center, and increased progressively to 86.87%, 86.39%, and 84.94% at 22.5 mm above. CC and RC were positively correlated, despite the different anteversion angles (r = 0.687 at 0°, 0.683 at 5°, and 0.645 at 10°; P < .001).

CONCLUSION

Computed tomography analysis and computer stimulation demonstrate that it is feasible to use high hip center technique in Crowe type III hips.

Reliability of the acetabular reconstruction technique using autogenous bone graft from resected femoral head in hip dysplasia: Influence of the change of hip joint center on clinical outcome

INTRODUCTION

The previous studies have not reached on consensus as to the outcome of acetabular reconstruction with autogenous bone graft for dysplastic hips, especially in severe cases such as Crowe type IV. The current study aimed to determine the survivorship of the arthroplasty and the grafts as well as the change of hip joint center averagely 9.8 years (range, 5-19) after cementless total hip arthroplasty.

MATERIALS AND METHODS

We reviewed 52 cases including 19 cases of complete hip dislocation of which acetabular defects were augmented with autogenous bone grafts taken from the resected femoral heads. For radiographic evaluation, in addition to checking failures of THA, acetabular coverages of the grafts as well as lateral center-edge angles were measured and compared between two time points, immediately postoperative and the final evaluations. Those outcomes were also analyzed according to the degree of hip dysplasia, grouping the subjects by Crowe classification. Translations of the reconstructed hip joint center after THA were measured and checked if they affected clinical outcomes or caused any complications. To assess clinically, Harris hip score and visualized analogue pain scale were reviewed.

RESULTS

Mean coverage ratio of the sockets with the grafts was 28.4% immediately after the surgery (range, 11.1%-65.0%) and 27.2% at the final follow-up (range, 11.1%-63.6%). When comparing high grade dysplasia (Crowe type III, IV) to low grade dysplasia (Crowe type I, II), there was no significant difference of the above outcomes (p = 0.476). As to the location of hip joint center, 14 outliers were located distally within the normal horizontal range especially in cases with Crowe type IV. Those outliers showed no difference on clinical outcome. The mean HHS was 52.2 (range, 19-87) and VAS was 7.2 (range, 5-9) preoperatively, each of which was improved to 92.9 (range, 63-100) and 1.4 (range, 0-4) postoperatively. No failures were experienced during the study period.

CONCLUSIONS

Acetabular augmentation using autogenous bone graft from the resected femoral head is found to be a successful method for dysplastic hip, even in severe cases such as Crowe type IV, showing favorable results in more than 8 years. When inevitable, a degree of compromise on hip joint center can be needed in dealing with severe hip dysplasia.

Cementless acetabular component with or without upward placement in dysplasia hip: Early results from a prospective, randomised study

BACKGROUND

Total hip arthroplasty (THA) in developmental dysplasia of hip (DDH) is difficult for the abnormal acetabulum. The purpose of this study was to evaluate the difference of anatomic and upward placement of acetabular component during early stage.

METHODS

From April 2014 through June 2015, forty DDH patients (Crowe I to III, 42 hips) were prospectively randomized to either anatomic or upward group. Patient recorded diaries were collected. Radiographs were reviewed. WOMAC and Harris scores were tabulated from pre-operation to 12 months after surgery.

RESULTS

The patients' characteristics including age and body mass index (BMI) had no significant difference (P > 0.05). There were no statistically differences between two groups for surgery time, intraoperative blood loss, hemoglobin (Hb), blood transfusion, albumin decrease, length of stay-day, but surgery time and blood loss in patients with structural bone graft was much higher in anatomic group. The postoperative limb-length discrepancy (LLD) was also no difference, but limb lengthening was better in anatomic group (P = 0.042). The total hospital costs in the anatomic group were higher, but no significant differences. With regard to Harris and WOMAC score, there were significant improved after surgery in both groups, and the anatomic group was better in the value, but these differences were no statistically significant.

CONCLUSIONS

Acetabular reconstruction for DDH subluxation should be reconstructed as close to the actual acetabular location as possible, but an appropriate (<20 mm) upward placement that can achieve at least 70% native bone coverage of the acetabular implant is a valuable technique for early faster recovery.

Posterosuperior Placement of a Standard-Sized Cup at the True Acetabulum in Acetabular Reconstruction of Developmental Dysplasia of the Hip With High Dislocation

BACKGROUND

We sought to evaluate posterosuperior placement of the acetabular component at the true acetabulum during acetabular reconstruction in patients with Crowe type-IV developmental dysplasia of the hip.

METHODS

Using pelvic computed tomography and image processing, we developed a two-dimensional mapping technique to demonstrate the distribution of preoperative three-dimensional cup coverage at the true acetabulum, determined the postoperative location of the acetabular cup, and calculated postoperative three-dimensional coverage for 16 Crowe type-IV dysplastic hips in 14 patients with a mean age of 52 years (33-78 years) who underwent total hip arthroplasty. Mean follow-up was 6.3 years (5.5-7.3 years).

RESULTS

On preoperative mapping, the maximum three-dimensional coverage using a 44-mm cup was 87.31% (77.36%-98.14%). Mapping enabled the successful replacement of 16 hips using a mean cup size of 44.13 mm (42-46 mm) with posterosuperior placement of the cup. Early weight-bearing and no prosthesis revision or loosening during follow-up were achieved in all patients. The postoperative two-dimensional coverage on anteroposterior radiographs and three-dimensional coverage were 96.15% (89.49%-100%) and 83.42% (71.81%-98.50%), respectively.

CONCLUSION

This technique may improve long-term implant survival in patients with Crowe-IV developmental dysplasia of the hip undergoing total hip arthroplasty by allowing the use of durable bearings, increasing host bone coverage, ensuring initial stability, and restoring the normal hip center.

Mid-term clinical and radiographic outcomes of porous tantalum modular acetabular components for hip dysplasia

It is still challenging to perform successful cementless cup fixation during total hip arthroplasty for hip dysplasia. In this multicenter study we evaluated the clinical results of porous tantalum modular acetabular cups (TM cups) in 45 dysplastic hips with a mean follow-up period of 9.8 years. The mean Japanese Orthopaedic Association hip score improved from 48.2 preoperatively to 92.1 at the most recent follow-up. All of the cups were radiographically stable with no evidence of progressive radiolucencies or osteolysis regardless of bone grafting. Sixteen hips with bone grafts showed the integration of grafted bone without any radiolucencies. There were no revisions of TM cups. The use of TM cups for dysplastic hips provided satisfactory 10-year clinical and radiographic results.

Fate of bone grafting for acetabular defects in total hip replacement

BACKGROUND

The use of allografts and autografts in the management of acetabular defects have been reported with varying results. Trabecular metal is an expensive option in the management of these defects. This study aims to assess the fate and efficacy of bone grafting for acetabular bone defects in total hip arthroplasty.

MATERIALS AND METHODS

A total of 30 hips in 28 patients with acetabular deficiencies were treated with bone grafting and total hip replacement (THR). Seventeen hips had American Academy of Orthopedic Surgeons (AAOS) type 2 (Paprosky type 2c) deficiency and 13 had AAOS type 3 (Paprosky type 3a) defects of the acetabulum. Allografts were used in 15 patients and autografts were used in the remaining 13. Cemented total hip arthroplasty was done in 18 hips and uncemented THR in 12. Seven patients underwent the procedure for, acetabular erosion and symptoms following hemiarthroplasty (4 out of 7), or, acetabular revision for failure (3 out of 7) following total hip arthroplasty. Acetabular deficiencies in other patients were due to posttraumatic causes, advanced primary hip arthritis and second stage treatment of postinfective arthritis. A mesh was used in 6 hips and screws were used in 13 hips for graft fixation.

RESULTS

Patients were followed up clinicoradiologically for a period of 10 months to 4 years (mean 23.4 months). One patient required staged revision due to infection. Two patients had early asymptomatic cup migration. One patient had graft lysis and change in cup inclination with persistent pain. He was not keen on further intervention at last followup. Other patients were pain free at the time of followup with radiographs showing maintenance of graft and implant position.

CONCLUSION

Bone grafting is a suitable option in the management of acetabular defects in total hip arthroplasty, especially in resource challenged countries.

Failure of bulk bone grafts after total hip arthroplasty for hip dysplasia

INTRODUCTION

Bulk bone grafts are used in total hip arthroplasty (THA) when adequate acetabular cup coverage cannot be achieved. Data from literature show mainly good short-term and mid-term results with contradictory long-term results. The aim of this study was to investigate acetabular cup stability and graft integrity after dysplastic adult hip reconstruction with total hip endoprosthesis and bulk bone graft for acetabular deficiency.

METHODS

Seventy-two hips in 64 patients that underwent THA with bone autograft or allograft were assessed immediately after operation, 6 months and 1, 2, 3 and 10 years after operation. Acetabular angle, acetabular cup coverage, bone graft width, and bone graft height were measured and questionnaire was designed to determine acetabular cup stability and grade graft integrity. Four investigators graded grafts and inter-rater and intra-rater reliability of the questionnaire was tested.

RESULTS

All measured parameters in all patients and in patients with autograft and those with allograft separately showed significant changes consistent with graft failure and acetabular cup instability when level of significance was set at p < 0.05.

CONCLUSIONS

Results of this study show significant decrease in acetabular cup stability when either autograft or allograft is used for cemented acetabular reconstruction of dysplastic hip. Further, allografts showed twice as rapid failure as autografts. Although these results contradict both good short-term and long-term results in published literature, they present warning for future use of free bulk bone grafts in reconstructive hip surgery.

Total hip arthroplasty with acetabular reconstruction using a bulk autograft for patients with developmental dysplasia of the hip results in high loosening rates at mid-term follow-up

PURPOSE

Managing a deficient acetabulum in patients with developmental dysplasia of the hip (DDH) can be challenging. The purpose of the study was to determine the mid-term results of total hip arthroplasty (THA) using a bulk structural autograft for reconstruction of the acetabular roof in patients with DDH.

METHODS

Between 1982 and 1999, 112 patients underwent THA with acetabular roof-plasty using a bulk structural autograft for secondary osteoarthritis related to DDH. A total of 106 patients (115 hips) met inclusion criteria and were followed for an average of 11.6 years (seven to 24 years). The mean age was 52.5 years at the index operation. Clinical and radiological evaluations were performed according to the methods of Merle d'Aubigné and Postel, Johnston et al. and DeLee and Charnley.

RESULTS

The overall Merle d'Aubigné hip score significantly improved (3.7 vs 10.4, p < 0.01). The limb length discrepancy decreased from 30 to 6 mm (p < 0.01). The average distance that the hip centre was distalised was 22.3 mm (0-56 mm). However, radiolucent lines were observed in 27 % of patients at final follow-up, and the overall rate of revision for aseptic loosening was 16 %. Further, Kaplan-Meier survivorship curves predicted a rapid increase in the failure rate at 15 years.

CONCLUSIONS

The mid-term functional outcome of THA with an acetabular roof-plasty using a bulk autograft is satisfactory; however, the long-term results are questionable.

Intraosseous structural graft technique: a new surgical concept in the treatment of superolateral defects in case of dysplastic acetabulum, during hip replacement surgery biomechanical and cadaver experimentations

PURPOSE

The replacement of the dysplastic hip, despite the numerous available surgical techniques, is not entirely solved. One of the reasons for this is the relative lack of bone in the acetabulum. In this study, we present a new concept (intraosseous structural graft technique), with the aim to improve the primary stability and biological environment of the graft.

METHODS

During the procedure in the cranial quadrant of the acetabulum, a proximally hinged cortico-spongious plate is fashioned that is opened laterally and a wedge-shaped graft made from the femoral head is impacted. The precisely fitted graft has good primary rotational and cranial stability which is further improved by a bicortical screw.

RESULTS

The hypothesis is supported by examination on 3D models. Cadaver experimentations were performed on 19 hips of 10 cadavers, and stability testing was done on a further 20 hips of 10 cadavers with a material testing apparatus. Also the analysis of the biological and mechanical properties of the graft and the implant were examined.

CONCLUSION

Based on our results, it can be concluded that our technique provides good primary stability with a more favorable biological condition for bony incorporation compared to other bulk bone graft techniques.

Total hip arthroplasty with bulk femoral head autograft for acetabular reconstruction in developmental dysplasia of the hip

Developmental hip dysplasia (DDH) presents considerable technical challenges to the primary arthroplasty surgeon. Autogenous bulk grafting using the femoral head has been utilised to achieve anatomic cup placement and superolateral bone coverage in these patients, but reported outcomes on this technique have been mixed with the lack of graft integration and subsequent collapse, an early cause of failures. We describe a novel technique combining the use of bulk autograft with an iliac osteotomy, which provides primary stability and direct cancellous-cancellous bone contact, optimising the environment for early osseointegration. Twenty-one hips in 21 patients with DDH underwent this technique and were followed for a mean of 8.1 years. The preoperative radiographic classification was Crowe type I in 12 hips (57%), type II in 4 hips, and type III in 5 hips, and the mean Sharp angle was 49.6° (range 42°–60°). All grafts united by year. At time of followup, there was no radiographic evidence of graft collapse or loosening. There were no reoperations. Our study has shown that this technique variation combining an iliac osteotomy with bulk autograft in cases of developmental hip dysplasia provides early stability and reliable graft incorporation, together with satisfactory clinical and radiological outcomes in the medium term. Longer term study is necessary to confirm the clinical success of this procedure.

Acetabular reconstruction in patients with low and high dislocation: 20- to 32-year survival of an impaction grafting technique (named cotyloplasty)

We report the results at a mean of 24.3 years (20 to 32) of 61 previously reported consecutive total hip replacements carried out on 44 patients with severe congenital hip disease, performed with reconstruction of the acetabulum with an impaction grafting technique known as cotyloplasty. The mean age of the patients at operation was 46.7 years (23 to 68) and all were women. The patients were followed post-operatively for a mean of 24.3 years (20 to 32), using the Merle d'Aubigné and Postel scoring system as modified by Charnley, and with serial radiographs. At the time of the latest follow-up, 28 acetabular components had been revised because of aseptic loosening at a mean of 15.9 years (6 to 26), and one at 40 days after surgery because of repeated dislocations. The overall survival rate for aseptic failure of the acetabular component at ten years was 93.1% (95% confidence interval (CI) 86.5 to 96.7) when 53 hips were at risk, and at 23 years was 56.1% (95% CI 49.4 to 62.8), when 22 hips remained at risk. These long-term results are considered satisfactory for the reconstruction of an acetabulum presenting with inadequate bone stock and circumferential segmental defects.

Revision of the acetabular component in dysplastic hips previously reconstructed with a shelf autograft: study of the outcome with special assessment of bone-stock changes

In this retrospective study we evaluated the proficiency of shelf autograft in the restoration of bone stock as part of primary total hip replacement (THR) for hip dysplasia, and in the results of revision arthroplasty after failure of the primary arthroplasty. Of 146 dysplastic hips treated by THR and a shelf graft, 43 were revised at an average of 156 months, 34 of which were suitable for this study (seven hips were excluded because of insufficient bone-stock data and two hips were excluded because allograft was used in the primary THR). The acetabular bone stock of the hips was assessed during revision surgery. The mean implant-bone contact was 58% (50% to 70%) at primary THR and 78% (40% to 100%) at the time of the revision, which was a significant improvement (p < 0.001). At primary THR all hips had had a segmental acetabular defect > 30%, whereas only five (15%) had significant segmental bone defects requiring structural support at the time of revision. In 15 hips (44%) no bone graft or metal augments were used during revision. A total of 30 hips were eligible for the survival study. At a mean follow-up of 103 months (27 to 228), two aseptic and two septic failures had occurred. Kaplan-Meier survival analysis of the revision procedures demonstrated a ten-year survival rate of 93.3% (95% confidence interval (CI) 78 to 107) with clinical or radiological failure as the endpoint. The mean Oxford hip score was 38.7 (26 to 46) for non-revised cases at final follow-up. Our results indicate that the use of shelf autografts during THR for dysplastic hips restores bone stock, contributing to the favourable survival of the revision arthroplasty should the primary procedure fail.

The biological and biomechanical comparison of two bulk bone graft techniques used in case of dysplastic acetabulum

BACKGROUND

The incorporation of bulk bone grafts in the replacement of dysplastic acetabulum is determined by the biological environment of the recipient site, the size of the contact surface, and the stability of the osteosynthesis used. Based on these, the present study compares the Harris acetabular plasty used routinely by us with the Radojević L-shaped graft technique.

METHODS

For our measurements, we used 20 hemi-pelvises removed from 10 cadavers. In 10 cases, acetabular plasty according to Harris, in 10 cases Radojević L-plasty, was performed. The biological environment was analyzed; with geometric calculations, the contact surface was determined, and with a material testing apparatus, the primary stability of the osetosynthesis was measured. For the measurements, a new method was developed.

RESULTS

The Radojević technique provides a better biological environment for graft ingrowth. The contact surface is nearly twice as much as in Harris plasty. No significant difference was found in the primary stability of the osteosynthesis used. The deviation on the value of the stability measurements is explained by the differences in the bone quality of the cadavers used.

CONCLUSIONS

Based on the 3 aspects examined, the Radojević L-shaped graft technique has similar stability when compared to the Harris acetabular plasty, but provides better biological circumstances and larger graft host bone contact. Based on this, we started using the L-shaped technique in our department.

Autogenous impaction grafting in total hip arthroplasty with developmental dysplasia of the hip

Autogenous impaction grafting was performed to improve acetabular cup coverage in 68 patients (78 hips) with developmental dysplasia of the hip (DDH) after total hip arthroplasty, and the patients were then monitored for a mean duration of 5.5years. No cup revisions were required, and there was no radiographic loosening. The host-graft interface became indistinct by 6weeks after surgery, trabecular bone formation was seen by 12weeks, and definite trabecular reorientation was seen by 20months. At the last follow-up examination, the mean cup coverage was 97.7%, whereas mean coverage by bone grafting was 27.9%. Among 12 patients with most of the bone graft placed at the absolutely protruded area of the cup, the cup coverage provided by the bone graft decreased from 95.4% immediately after surgery to 20.7% by the final follow-up examination. Bone-particle grafting can provide a satisfactory integration speed and a low incidence of displacement and ectopic ossification.

Primary total hip arthroplasty with a spongy metal surface acetabular component for hip dysplasia

We evaluated the clinical and radiographic results of primary total hip arthroplasty for 81 dysplastic hips (71 patients) using cementless Spongiosa Metal II cups (ESKA Implants, Lübeck, Germany). The mean follow-up period was 6.4 years (minimum 5 years), and the preoperative mean Japanese Orthopaedic Association hip score had improved from 45.2 to 87.4 points at the latest follow-up. The radiographic outcome was no aseptic loosening in all 81 hips. The hip center was located significantly more superior than in the contralateral normal hip in 45 patients, but the difference was less than 10 mm; however, there was no significant difference in the lateral position of the hip center. The use of a Spongiosa Metal II cup for dysplastic hips provided satisfactory 5- to 10-year clinical and radiographic results.

High survivorship of cemented sockets with roof graft for severe acetabular dysplasia

BACKGROUND

Socket fixation in patients with acetabular dysplasia can be technically demanding but the use of structural grafts can help to reconstruct the original center of hip rotation. Because reported survival rates differ, construct survival seems to depend on the technique of graft preparation and fixation.

QUESTIONS/PURPOSES

What is the survivorship of cemented sockets with acetabular roof graft in patients with severe acetabular dysplasia? Do clinical scores equal those of patients without acetabular grafting?

METHODS

We retrospectively reviewed 62 patients (74 hips) who had undergone cemented THA with acetabular roof graft. Mean age at surgery was 45 years (range, 19-71 years). Revisions and radiographic failures were determined and clinical scores (Oxford, SF-12) were obtained and matched to a control group. Kaplan-Meier analysis was used to determine survivorship at a minimum followup of 5 years (mean, 10.4 years; range, 5-16 years).

RESULTS

Survivorship for all-cause revision was 98% (95% CI, 92.5%-100.0%) at 10 years followup. Two hips were revised for aseptic acetabular loosening and one hip for polyethylene wear. All grafts incorporated and no additional radiographic loosenings were seen. Patients with grafting had higher Oxford scores compared with the control group but other scores were equal.

CONCLUSIONS

In contrast to reported series and the common use of cementless cups in patients with developmental dysplasia of the hip, we found high survivorship of cemented sockets with roof graft in severe acetabular dysplasia at a mean followup of more than 10 years. These patients showed higher Oxford scores than patients in a control group. This technique that restores bone stock is a reasonable solution for often young patients with dysplasia.

LEVEL OF EVIDENCE

Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

Incidence and natural course of initial polar gaps in Birmingham Hip Resurfacing cups

The purpose of this study was to retrospectively investigate the incidence of initial polar gaps and their effect on clinical results in Birmingham Hip Resurfacing cups. A total of 151 hips in 134 patients who underwent hip resurfacing at a mean age of 50 years were examined. The mean follow-up period was 7 years. A polar gap was identified in 47 hips (31%) with a mean width of 2.1 mm. Gaps of 2 mm or more were identified in 21 hips, 6 of which showed reductions in cup inclination during the initial 3 months. After 3 months, no progressive cup migration was observed. There was no cup revision. All gaps were filled with bone within 2 years of surgery. The initial polar gaps had no significant influence on the stability of hydroxyapatite-coated Porocast cobalt-chromium hemispherical monoblock cups (Midland Medical Technologies Ltd, Birmingham, UK), although gaps of 2 mm or more had a higher risk of early migration.

15-year comparison of cementless total hip arthroplasty with anatomical or high cup placement for Crowe I to III hip dysplasia

This study compared radiological and clinical results of Mallory-Head (Biomet, Warsaw, Indiana) cementless total hip arthroplasty (THA) by anatomical (AP group) or high cup placement (HP group) for Crowe I to III developmental dysplasia of the hip. Of the 68 hips studied, 43 hips were available for 15.3-year follow-up. Ten cups were placed at anatomical center with bulk bone grafting, and 33 cups were at high hip center without bulk bone grafting. No acetabular or femoral components showed loosening in either group. One standard polyethylene liner in a highly placed cup was revised due to excessive wear after 11 years. The average rate of polyethylene wear was 0.128 mm/year in the AP group and 0.148 mm/year in the HP group (except for the revision case). The extent of grafted bone coverage was 34.6% in the AP group. Hip center height was 24.5 mm from the inter-teardrop line in the HP group. The center of the hip horizontal location in the AP group (24.5 mm) and HP group (26.4 mm) was significantly shorter than in normal hips (35.6 mm). Postoperative center-edge angle was 11° (except grafted bone) in the AP group and 25° in the HP group. Mean Harris Hip Score in the AP group improved from 38 points preoperatively to 82 points postoperatively and in the HP group improved from 40 points preoperatively to 88 points postoperatively. Survivorship was 100% in the AP group and 97% in the HP group. Our results indicate that moderate high cup placement without bulk bone grafting at a horizontal locus more medial than that of a normal hip is an alternative durable solution.

Bulk femoral head autograft without decortication in uncemented total hip arthroplasty: seven- to ten-year results

Superolateral acetabular bone defect is a serious challenge in uncemented total hip arthroplasty for acetabular dysplasia. We report a bulk bone autografting technique without decortication of the acetabulum and femoral head contact surfaces in 22 joints. Mean follow-up time was 8.3 years, and survival rates were 100% for loosening and revision end points. The preoperative Japanese orthopedic association hip score increased from 49.5 to 94.0. Although trabecular bridging and graft remodeling occurred in all cases, complete trabecular reorientation was observed in only 15 joints. Eccentric polyethylene wear was observed in 8 of 22 joints, and osteolysis, in 1 joint. Our technique is easy to perform, and midterm results were favorable; thus, we conclude that it may be an effective option for bulk bone autografting.

The 15° face-changing acetabular component for treatment of osteoarthritis secondary to developmental dysplasia of the hip

We report the use of a 15° face-changing cementless acetabular component in patients undergoing total hip replacement for osteoarthritis secondary to developmental dysplasia of the hip. The rationale behind its design and the surgical technique used for its implantation are described. It is distinctly different from a standard cementless hemispherical component as it is designed to position the bearing surface at the optimal angle of inclination, that is, < 45°, while maximising the cover of the component by host bone.

Treatment for acetabular dysplasia using the uncemented RM acetabular component - a 20 year follow-up

Our study reports a sub-group of patients with developmental dysplasia from a previously published larger series, with particular emphasis on the use of the uncemented RM acetabular component. We evaluated the long term results of 93 consecutive uncemented THAs in 80 patients using the titanium-coated RM acetabular component and the CLS femoral component in a prospective study. Eighteen hips in 16 patients had osteoarthritis secondary to developmental dysplasia of the hip. The mean follow-up was 19.6 years (18.2 to 20.9). Fourteen patients with 15 hips were clinically and radiographically examined and evaluated. Two patients with 3 hips died. No patient was lost to follow-up. No implant had to be revised, and no cases showed evidence of radiographic loosening. Nine acetabular components were not completely covered by host bone but this did not affect the outcome. At the latest follow-up the mean Harris Hip Score was 92 (81 to 100). The mean annual wear rate was 0.12 mm. The RM acetabular component performed well over 20 years in this selected group of patients. Complete acetabular containment was not needed, thus allowing reliable reconstruction of the anatomical centre of rotation.

High long-term survival of bulk femoral head autograft for acetabular reconstruction in cementless THA for developmental hip dysplasia

BACKGROUND

Deficient acetabula associated with acetabular dysplasia cause difficulty achieving adequate coverage of the acetabular component during THA. Autografting with the removed femoral head has been used for several decades to achieve better coverage, but the long-term benefits of this technique remain controversial, with some series reporting high rates of graft resorption and collapse.

QUESTIONS/PURPOSES

We evaluated the fate of bulk femoral head autograft for acetabular reconstruction in cementless THA for developmental hip dysplasia.

PATIENTS AND METHODS

We retrospectively reviewed 70 patients (83 hips) (68 women, two men) with a mean age of 57 years at index surgery. According to the classification of Crowe et al. for hip dysplasia, 10 hips were classified as Type I, 45 as Type II, 19 as Type III, and nine as Type IV. Minimum followup was 9 years (mean, 11 years; range, 9-14 years).

RESULTS

We observed no collapsed grafts. In all patients we observed disappearance of the host-graft interface and appearance of radiodense bands in the grafts bridging host iliac bone and at the lateral edges of the acetabular sockets; remodeling with definite trabecular reorientation was seen in 90%. The 10-year survival rate without acetabular revision for any reason was 94%. The mean Merle d'Aubigné and Postel hip score improved from a mean of 9.1 preoperatively to 17.2 at last followup.

CONCLUSIONS

Cementless THA combined with autologous femoral bone graft in patients with developmental dysplasia resulted in a high rate of survival. Structural bone grafting achieved a stable construct until osseointegration occurred. We believe the radiodense bands represent a radiographic sign of successful completion of repair of the deficient acetabulum. Congruous and stable contact of the cancellous portion of the graft to the host bed by impaction and use of improved porous cementless sockets may be associated with successful socket survival.

LEVEL OF EVIDENCE

Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Minimum ten-year results of a porous acetabular component for Crowe I to III hip dysplasia using an elevated hip center

We conducted a retrospective study of the placement of porous-coated acetabular components using screws at more than 20 mm above the teardrop without structural bone graft for dysplastic hips to determine long-term outcome. Thirty hips (29 patients) were monitored for a mean of 15.2 years (range, 10.4-18.3 years) after surgery. Compared with 12 contralateral normal hips, the distance of the hip center from the teardrop was significantly high (26.8 +/- 4.8 and 13.4 +/- 2.7 mm P < .001); however, it was not laterally different (31. 5 +/- 5.1 and 31.7 +/- 5.0 mm). No acetabular components showed loosening. One metal shell was revised for wear and osteolysis. Morselized bone grafted in 25 hips was incorporated in all cases. Slight elevation of the hip center without lateralization in cementless cups fixed with screws was well tolerated for dysplastic hips.

Metal-on-metal hip resurfacing in developmental dysplasia: a case-control study

Metal-on-metal hip resurfacing was performed for developmental dysplasia in 96 hips in 85 patients, 78 in women and 18 in men, with a mean age at the time of surgery of 43 years (14 to 65). These cases were matched for age, gender, operating surgeon and date of operation with a group of patients with primary osteoarthritis who had been treated by resurfacing, to provide a control group of 96 hips (93 patients). A clinical and radiological follow-up study was performed. The dysplasia group were followed for a mean of 4.4 years (2.0 to 8.5) and the osteoarthritis group for a mean of 4.5 years (2.2 to 9.4). Of the dysplasia cases, 17 (18%) were classified as Crowe grade III or IV. There were five (5.2%) revisions in the dysplasia group and none in the osteoarthritic patients. Four of the failures were due to acetabular loosening and the other sustained a fracture of the neck of femur. There was a significant difference in survival between the two groups (p = 0.02). The five-year survival was 96.7% (95% confidence interval 90.0 to 100) for the dysplasia group and 100% (95% confidence interval 100 to 100) for the osteoarthritic group. There was no significant difference in the median Oxford hip score between the two groups at any time during the study. The medium-term results of metal-on-metal hip resurfacing in all grades of developmental dysplasia are encouraging, although they are significantly worse than in a group of matched patients with osteoarthritis treated in the same manner.

Acetabular reinforcement ring in primary total hip arthroplasty: a minimum 10-year follow-up

INTRODUCTION

We report the results of a titanium acetabular reinforcement ring with a hook (ARRH) in primary total hip arthroplasty (THA), which was introduced in 1987 and continues to be used routinely in our center. The favorable results of this device in arthroplasty for developmental dysplasia and difficult revisions motivated its use in primary THA. With this implant only minimal acetabular reaming is necessary, anatomic positioning is achieved by placing the hook around the teardrop and a homogenous base for cementing the polyethylene cup is provided.

MATERIALS AND METHODS

Between April 1987 and December 1991, 241 THAs with insertion of an ARRH were performed in 178 unselected, consecutive patients (average age 58 years; range 30-84 years) with a secondary osteoarthrosis in 41% of the cases.

RESULTS

At the time of the latest follow-up, 33 patients (39 hips) had died and 17 cases had been lost to follow-up. The median follow-up was 122 months with a minimum of 10 years. Eight hips had been revised, leaving 177 hips in 120 living patients without revision. Six cups were revised because of aseptic loosening. Two hips were revised for sepsis. The mean Merle d'Aubigné score for the remaining hips was 16 (range 7-18) at the latest follow-up. For aseptic loosening, the probability of survival of the cup was 0.97 (95% confidence interval, 0.94-0.99). However, analysis of radiographs implied loosening in seven other cups without clinical symptoms.

CONCLUSIONS

The results of primary THA using an acetabular reinforcement ring parallel the excellent results of these implants often observed in difficult primary and revision arthroplasty at a minimum of 10 years. Survivorship is comparable to modern cementless implants. Medial migration that occurs with loosening of the acetabular component seems to be prevented with this implant. Radiographic loosening signs can exist without clinical symptoms.

Primary total hip arthroplasty with Asian-type AML total hip prosthesis: follow-up for more than 10 years

BACKGROUND

We retrospectively reviewed 137 consecutive total hip arthroplasties performed with AML-A stems and Tri-Lock cups to see whether design modifications made to these components would achieve durable biological fixation in the Japanese population in whom developmental dysplasia of the hip (DDH) is relatively common. Patients from our initial clinical series using these components are available for more than 10 years' follow-up.

METHODS

Between April 1988 and June 1994, we performed 137 total hip arthroplasties using the AML-A prosthesis for the patients with osteoarthritis of the hip joint. We excluded 26 hips with less than 10 years' follow-up and five hips from patients who died before the 10-year follow-up. The mean follow-up for the 105 remaining THAs is 155.2 months (range 120-237 months). The average age of these patients at the time of surgery was 53.1 years (range 22-81 years).

RESULTS

In total, 17 THAs required component revisions. In seven cases, the first revision was limited to a liner exchange for polyethylene wear or osteolysis. Another seven hips underwent revision surgery for recurrent dislocation. Three cups have been revised owing to aseptic loosening. Because of the high incidence of wear-related revisions, Kaplan-Meier survivorship at the 15-year follow-up, using acetabular component revision for any reason as an endpoint, was 75.0% (95% CI 69.4%-83.8%). In contrast, no revision of the femoral stem was performed. Severe stress shielding occurred in 12 hips. Thigh pain was mild, however, and all of the femoral stems remained stable.

CONCLUSIONS

Despite revisions for wear-related complications, the fixation achieved with these porous-coated components remained durable throughout the 15-year follow-up. Acetabular osteolysis has been associated with cup reoperation, but femoral stress shielding has never resulted in stem loosening.

Favorable survival of acetabular reconstruction with bone impaction grafting in dysplastic hips

Acetabular bone loss hampers implantation of a total hip arthroplasty in patients with developmental dysplasia of the hip. The bone impaction grafting technique in combination with a cemented total hip can restore the bone stock in these patients, but do these reconstructions yield satisfying long-term results? We used this technique in 28 hips (22 consecutive patients). The degree of dislocation was graded preoperatively as Crowe I in five hips, Crowe II in eight hips, Crowe III in nine hips, and Crowe IV in four hips. We present the long-term results of this bone impaction grafting technique a minimum of 10 years after surgery. Two patients died before the minimum followup of 10 years, leaving 20 patients (26 hips). Two cups were revised, one cup for a sciatic nerve palsy (at 2 years) and the other for aseptic loosening after 12 years. The cumulative survival of the cup with revision for any reason as the end point was 96% at 10 years and 84% at 15 years. There were no femoral revisions during followup. The bone impaction grafting technique in combination with a cemented cup is an effective technique for developmental dysplasia of the hip with favorable long-term results.

LEVEL OF EVIDENCE

Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

Bone Regeneration on a Collagen Sponge Self-Assembled Peptide-Amphiphile Nanofiber Hybrid Scaffold

The objective of this study was to create a novel approach to promote bone induction through sustained release of growth factor from a 3-dimensional (3D) hybrid scaffold. Peptide-amphiphile (PA) was synthesized by standard solid-phase chemistry that ends with the alkylation of the NH2 terminus of the peptide. Collagen sponge was reinforced by incorporation of poly(glycolic acid) (PGA) fiber. A 3D network of nanofibers was formed by mixing basic fibroblast growth factor (bFGF) suspensions with dilute aqueous solutions of PA. A hybrid scaffold was fabricated by combination of self-assembled PA nanofibers and collagen sponge reinforced with incorporation of PGA fibers. The in vitro release profile of bFGF from hybrid scaffold was investigated, and ectopic bone formation induced by the released bFGF was assessed after subcutaneous implantation of hybrid scaffold into the backs of rats. Homogeneous bone formation was histologically observed throughout the hybrid scaffolds, in marked contrast to collagen sponge-incorporated bFGF. The level of alkaline phosphatase activity and osteocalcin content at the implanted sites of hybrid scaffolds were significantly high compared with collagen sponge incorporated with bFGF. The combination of bFGF incorporated in a collagen sponge self-assembled PA nanofiber hybrid scaffold is a promising procedure to improve bone regeneration.

Biological responses to multilayered DNA-coatings

This study was performed to evaluate the basic biological response to deoxyribonucleic acid (DNA)-based coatings for soft tissue implants. To that end, in vitro experiments were used to study their cytocompatibility, and in vivo subcutaneous implantation studies with transponders in a rat model were performed to evaluate their histocompatibility. The DNA-based coatings were fabricated using the electrostatic self-assembly technique using cationic poly-D-lysine or poly-allylamine hydrochloride and anionic DNA. Noncoated substrates served as controls. In vitro, the behavior of primary rat dermal fibroblasts was assessed in terms of cell proliferation and morphology. Both types of multilayered DNA-coatings significantly increased rat dermal fibroblast proliferation without altering the morphological appearance of the cells. The tissue response to multilayered DNA-coatings was assessed using an in vivo rat model, in which transponders were inserted subcutaneously for 4 and 12 weeks. No macroscopic signs of inflammation or adverse tissue reactions were observed at implant retrieval. Histological analyses demonstrated a uniform tissue response to all types of implants. All implants were encapsulated in a fibrous tissue capsule without intervening inflammatory cells at the implant surface. Histomorphometrically, multilayered DNA-coatings induced fibrous tissue capsules with similar quality and thickness compared to noncoated controls. In addition, all fibrous tissue capsules showed similar expression of alpha-smooth muscle actin. This study demonstrates that multilayered DNA-coatings are cytocompatible and histocompatible, and justifies further research on their functionalization with biologically active compounds to modulate tissue responses.