Complex cemented revision using polished stem and morselized allograft

The aim of this study was to evaluate the results of complex hip revision using a cemented, collarless and polished femoral stem design (CPT, Zimmer, Warsaw, In.) within a tightly impacted morselized allograft. We have now been using the impaction grafting technique in combination with the CPT stem (Zimmer) for 10 years in complex cases of severe bone loss. In this study we have elected to report only those patients who have been revised at least once before revision using the impaction grafting technique. All the patients in the study group have a minimum follow-up of 5 years after the impaction grafting revision. In total, 43 consecutive hips in 40 patients, 22 men and 18 women, with a follow-up time of between 5 and 7 years are included in the study. The complications related to the revised hip consist of three early dislocations managed by closed reduction. Two patients suffered from periprosthetic fracture, both managed with plate osteosynthesis. Two cementless sockets were revised due to aseptic socket loosening. The Endoklinik rating of preoperative bone loss for the revised hips was 2 in 13 hips, 3 in 23 hips, and 4 in 7 hips. During the first year 29 stems subsided 2-4 mm within the cement mantle. In 8 cases, a subsidence of 5-9 mm was measured. The subsidence was nonprogressive, and no subsidence occurred after the 1st year. The Charnley, D'Aubigne, Postel scoring (maximum 6 points) for pain improved from 2.2 points preoperatively to 4.4 postoperatively, function from 2.3 to 4.3, and movement from 2.3 to 4.1. In conclusion, the concept of impaction grafting in THR revision in our study has so far proven to be successful with good clinical results at 5 years despite the relatively high early subsidence of the femoral component.     

非骨水泥长柄假体结合同种异体颗粒骨植骨在股骨翻修骨缺损重建中的应用

目的 回顾性分析股骨髓内同种异体颗粒骨打压植骨结合非骨水泥长柄假体在髋关节翻修术中股骨侧骨缺损修复应用的近期临床效果.方法 2003年7月至2009年6月对27例股骨侧骨缺损患者采用同种异体颗粒骨打压植骨,其中男性15例,女性12例,年龄47～78岁,平均67岁.失败原因:骨溶解、无菌性松动20例,全髋关节置换术后假体周围感染二期翻修7例.按Paprosky分型标准,Ⅱ型骨缺损3例,Ⅲ型骨缺损2l例,Ⅳ型骨缺损3例.术中均采用同种异体颗粒骨打压植骨、非骨水泥翻修柄植入.定期随访复查,包括临床、影像学评估,观察假体有无松动、下沉,植入骨活化替代情况以及假体周围骨折等并发症.Harris评分术前平均43分(37～62分).结果 23例患者获得随访,随访时间3～47个月,平均26.4个月.术后末次随访时.Harris评分平均83分(67～97分).术中2例发生股骨大转子骨折,无一例发生术后假体周围骨折等并发症.1例术后发生关节脱位,1例发生深静脉血栓,1例术后2周发生急性感染,经扩创、置管冲洗、抗感染治疗成功保留假体;发生异位骨化1例,Brooker Ⅰ级.影像学所有患者股骨柄中置,无内翻或外翻,随访期内无一例发生股骨柄移位(内翻或外翻角度变化>3°).23例患者显示至少Ⅰ区股骨髓内移植骨与周围骨或与股骨柄整合.4例发生股骨柄假体下沉,平均下沉3.3 mm(2～6 mm).结论 股骨侧翻修中,良好的股骨髓内同种异体颗粒骨打压植骨结合合适的非骨水泥延长柄股骨假体,可以修复关节置换术后各种原因所导致股骨骨缺损、重建股骨完整性,具有很好的近期临床疗效.但中远期临床效果尚待进一步观察.     

Defining the impaction frequency and threshold force required for femoral impaction grafting in revision hip arthroplasty

Background and purpose The two most common complications of femoral impaction bone grafting are femoral fracture and massive implant subsidence. We investigated fracture forces and implant subsidence rates in embalmed human femurs undergoing impaction grafting. The study consisted of two arms, the first examining the force at which femoral fracture occurs in the embalmed human femur, and the second examining whether significant graft implant/subsidence occurs following impaction at a set force at two different impaction frequencies.

Methods Using a standardized impaction grafting technique with modifications, an initial group of 17 femurs underwent complete destructive impaction testing, allowing sequentially increased, controlled impaction forces to be applied until femoral fracture occurred. A second group of 8 femurs underwent impaction bone grafting at constant force, at an impaction frequency of 1 Hz or 10 Hz. An Exeter stem was cemented into the neomedullary canals. These constructs underwent subsidence testing simulating the first 2 months of postoperative weight bearing.

Results No femurs fractured below an impaction force of 0.5 kN. 15/17 of the femurs fractured at or above 1.6 kN of applied force. In the second group of 8 femurs, all of which underwent femoral impaction grafting at 1.6 kN, there was no correlation between implant subsidence and frequency of impaction. Average subsidence was 3.2 (1–9) mm.

Interpretation It is possible to calculate a force below which no fracture occurs in the embalmed human femur undergoing impaction grafting. Higher impaction frequency at constant force did not reduce rates of implant subsidence in this experiment.     

Impaction allograft with cement for the revision of the femoral component. A minimum 39-month follow-up study with the use of the Exeter stem in Asian hips

We report the results of impaction bone grafting of the femoral side in revision total hip arthroplasty in Asian hips (South Korean patients) in which the surgery was performed with the use of the Exeter stem. The minimum follow-up was 39 months (mean, 48.4; range, 39-66). There was subsidence of the cement-graft interface (<1 mm) in three hips (5%), of the stem-cement interface (<1 mm) in 12 hips (21%) and of the stem-cement interface (1-2 mm) in 14 hips (25%). Five hips (9%) developed intraoperative femoral fracture and two hips (4%) femoral perforation in revision. The complications of femoral fracture and subsidence did not have an adverse effect on the final clinical outcomes. The impaction of fresh-frozen allograft and use of a cemented, polished, tapered stem (Exeter stem) were also successful with good clinical and radiographic outcomes in our study of Asian hips (South Korean patients). However, we used smaller stems than the usual ones used for Western patients because of the smaller femur sizes.     

A customised collared polished stem may reduce the complication rate of impaction grafting in revision hip surgery: a 12-year follow-up study

We describe the results of 81 consecutive revision total hip replacements with impaction grafting in 79 patients using a collared polished chrome-cobalt stem, customised in length according to the extent of distal bone loss. Our hypothesis was that the features of this stem would reduce the rate of femoral fracture and subsidence of the stem. The mean follow-up was 12 years (8 to 15). No intra-operative fracture or significant subsidence occurred. Only one patient suffered a post-operative diaphyseal fracture, which was associated with a fall. All but one femur showed incorporation of the graft. No revision for aseptic loosening was recorded. The rate of survival of the femoral component at 12 years, using further femoral revision as the endpoint, was 100% (95% confidence interval (CI) 95.9 to 100), and at nine years using re-operation for any reason as the endpoint, was 94.6% (95% CI 92.0 to 97.2). These results suggest that a customised cemented polished stem individually adapted to the extent of bone loss and with a collar may reduce subsidence and the rate of fracture while maintaining the durability of the fixation.     

Defining the impaction frequency and threshold force required for femoral impaction grafting in revision hip arthroplasty. A human cadaveric mechanical study

Background and purpose

The two most common complications of femoral impaction bone grafting are femoral fracture and massive implant subsidence. We investigated fracture forces and implant subsidence rates in embalmed human femurs undergoing impaction grafting. The study consisted of two arms, the first examining the force at which femoral fracture occurs in the embalmed human femur, and the second examining whether significant graft implant/subsidence occurs following impaction at a set force at two different impaction frequencies.

Methods

Using a standardized impaction grafting technique with modifications, an initial group of 17 femurs underwent complete destructive impaction testing, allowing sequentially increased, controlled impaction forces to be applied until femoral fracture occurred. A second group of 8 femurs underwent impaction bone grafting at constant force, at an impaction frequency of 1 Hz or 10 Hz. An Exeter stem was cemented into the neomedullary canals. These constructs underwent subsidence testing simulating the first 2 months of postoperative weight bearing.

Results

No femurs fractured below an impaction force of 0.5 kN. 15/17 of the femurs fractured at or above 1.6 kN of applied force. In the second group of 8 femurs, all of which underwent femoral impaction grafting at 1.6 kN, there was no correlation between implant subsidence and frequency of impaction. Average subsidence was 3.2 (1–9) mm.

Interpretation

It is possible to calculate a force below which no fracture occurs in the embalmed human femur undergoing impaction grafting. Higher impaction frequency at constant force did not reduce rates of implant subsidence in this experiment.With the increasing success of acetabular impaction bone grafting in dealing with loss of acetabular bone stock, attempts were made to use the technique to fill femoral bone defects in revision hip arthroplasty. The results of femoral impaction grafting have been satisfactory. In a recent review of over 1,000 femoral impaction graftings, Ornstein et al. (2009) reported 15-year implant survival rates of 94%, with minimal difference in implant survivorship between low- and high-volume units, suggesting that the technique of femoral impaction grafting appears to be, “reliable, can be learned rapidly, and produces a predictably low incidence of aseptic loosening.”Despite these results, however, there is still concern regarding the high rate of complications of femoral impaction grafting, the main complications being operative or perioperative femoral fracture and implant subsidence. Fracture rates of up to 16% have been reported (Masterson et al. 1997, Leopold et al. 1999, Pekkarinen et al. 2000). High rates of implant subsidence have also been described (Eldridge et al. 1997, Masterson et al. 1997), which may be due to inadequate impaction of the morselized bone graft. Thus, increasing the impaction force will ensure improved graft stability but will increase the risk of femoral fracture.In a preliminary study on sow femurs, Flannery et al. (2010) achieved a stable construct without fracture. A stable construct was defined as a femur that underwent impaction bone grafting at sub-threshold force, with a cemented Exeter stem that did not undergo massive early subsidence (10 mm) on initial subsidence testing simulating the first 2 postoperative months of weight bearing. The authors were unable to find any correlation between threshold force, bone mineral density, cortex-to-canal ratio, or cortical thickness in impaction bone grafting in the adult sow femur.In this study, we applied the experimental protocol of Flannery et al. (2010) to a sample of adult human femurs and investigated the above associations—but with the addition of measurement of cortex-to-canal ratios on standardized pretesting plain radiographs.The compaction of the bone graft may also be dependent on the frequency of impaction. In a laboratory study on impacted pig bone, Marck Van Liefland (2006) reported that “high-frequency impaction achieved high compaction at low load.” in a pot of morselized pig bone graft. While high compaction was achieved, the author did not state how far the graft had compressed. “Compared to traditional impaction, the same amount of compaction was achieved at 10–20% of the load. Inversely, compaction almost doubled at the same load.” Thus, prevention of massive early subsidence of the femoral component may also be dependent on the frequency of impaction to obtain adequate compaction, possibly permitting lower forces to be applied at higher frequencies and possibly reducing fracture risk.A final subset of femurs then underwent impaction bone grafting at set impaction force. This was followed by subsidence testing with a cemented Exeter stem, half at an impaction frequency of 1 Hz and the other half at an impaction frequency of 10 Hz.     

Impacted cancellous graft plus cement in hip revision

Revision of the femoral component is difficult in the presence of large cavitary defects of the femur. Impaction cancellous grafting used in conjunction with a cemented prosthesis has been recommended as a means of restoring bone stock while providing excellent and durable clinical results. Fifty-seven consecutive femoral revisions were done between 1993 and 1997 in 54 patients (24 men and 30 women) using the impaction grafting technique and a collarless, tapered, polished stem. Strut allografts were used for femoral reinforcement in 40 hips. No patient was lost to followup. One patient had an infection develop and had a resection arthroplasty. Three patients died of causes unrelated to the hip. After 6.3 years the clinical results were excellent. Radiographic evaluation showed no evidence of loosening in any of the 53 surviving hips. Subsidence of 1 to 3 mm was seen in 40 hips and subsidence of 4 to 6 mm was seen in two hips. Cancellous remodeling was observed in 42 hips. The most common complications were postoperative femoral fractures. All six fractures occurred at the distal end of the prosthesis, were not associated with prosthetic loosening, and were treated successfully with open reduction and internal fixation without prosthetic revision. These satisfactory results and the limited subsidence observed in our patients radiographs could be explained by the careful attention to the technical details of the procedure. However, even with the generous use of strut graft augmentation, postoperative femoral fractures remain our most serious complication.     

Migration of the femoral stem after impaction bone grafting. First results of an ongoing,randomised study of the exeter and elite plus femoral stems using radiostereometric analysis

We report the initial results of an ongoing randomised, prospective study on migration of the Exeter and Elite Plus femoral stems after impaction allografting, as measured by radiostereometry. Clinically, the impaction technique gave good results for both stems. The mean subsidence in the first year was 1.30 mm and 0.20 mm for the Exeter and the Elite Plus stems, respectively. In the second year, the Exeter stem continued to subside further by a mean of 0.42 mm, while the Elite Plus stem did not do so. Subsidence of the Exeter stem correlated with deficiency of bone stock as graded on the Gustilo and Pasternak scale. This correlation was not found for the Elite Plus stem. None of the other parameters which were studied predisposed to subsidence. There was no significant association between the amount of subsidence and the radiological appearance of the graft for either stem. Our findings do not support the theory that radial compression, due to subsidence of the Exeter stem, is the essential stimulus for remodelling in impaction allografting.     

Revision of total hip arthroplasty using an anterior cortical window, extensive strut allografts, and an impaction graft: follow-up study

PURPOSE: To report the outcome of revised total hip arthroplasty procedures involving an anterior cortical window, extensive strut allografts, and an Exeter impaction graft. METHOD: Eight patients (9 hips) with a mean age of 58 years underwent revision of total hip arthroplasty using the Exeter hip impaction graft system and strut allografts between 1995 and 1998. An extensile anterior approach was used, and an anterior cortical window was created in the femur, to remove the old implant. External strut allografts were attached by wires to provide cortical support. The mean follow-up duration was 74 months. Indications for surgery were aseptic loosening of previous implants in 8 hips and infection of one hip that had previously undergone total arthroplasty. RESULTS: 19 Dall Miles cables, 4 ordinary cerclage wires, and 8 cerclage wires tightened with the clincher knot technique were used to secure the allograft to the host bone. The strut grafts were found to be incorporated in all cases. No wires became loose. One patient developed 20 degrees of angulation at the allograft-host bone junction. Using the method of Fowler and Gie, we found that one femoral implant had subsided 2 mm within the cement mantle. Two other implants had 1 mm of subsidence at the cement bone interface, and one patient had a major subsidence of 15 mm that required revision. CONCLUSION: Using an anterior cortical window in the femur to remove the old implant does not predispose to failure of the allograft to incorporate into the host bone.     

Impaction bone grafting for femoral revision hip arthroplasty with Exeter Universal stem in Japan

Objectives

The purpose of the present study was to analyze the retrospective clinical and radiographic results of femoral revision arthroplasties with impaction bone grafting performed by experienced Japanese surgeons.

Patients and methods

We investigated the radiographic and clinical records more than 2?years after the surgery in 99 hips of 93 patients. The average age was 66.3?years (36–84?years) and the average follow-up period was 5.2?years (2–13?years). The Merle d’Aubigné and Postel hip score was used for clinical assessment, and peri-operative fractures were recorded. The survival curve was estimated using Kaplan–Meier method.

Results

The mean Merle d’Aubigné and Postel hip score improved from 9.0 points to 15.2 points at the final follow-up. Augmentations for segmental defect of femoral cortices were undertaken in 55 hips. Metal or strut allograft plates were applied to 9 hips and 21 hips, respectively. Intra-operative fractures or perforations occurred in 20 hips. Re-operations of the femur were undertaken in nine hips including five post-operative femoral fractures. More than 5?mm of subsidence was observed in only 2 hips. The survival rates at 8?years after the operation were 94.8?% with femoral fractures as the end point, 93.1?% with any stem removal or exchange as the end point, and 99.0?% with aseptic stem loosening as the end point, respectively.

Conclusion

The present study showed encouraging mid-term results of impaction bone grafting for femoral revision arthroplasty by experienced surgeons in Japan. Aggressive augmentation of segmental defects and attenuated femoral shafts prevents massive stem subsidence and periprosthetic fracture.     

Favorable mid-to-long-term results of impaction bone grafting using a fresh frozen allograft bone with cemented stem for the treatment of Paprosky IV femoral bone defects

BackgroundFemoral revision surgery in patients with substantial bone loss is challenging. Impaction bone grafting using a cemented stem can be a good solution for reconstruction of the femur with poor bone stock and extensive bone loss. This study aimed to evaluate the mid-to-long-term clinical and radiographic results of impaction bone grafting using a cemented stem for Paprosky IV femoral bone defects.MethodsThirteen patients (13 hips) who underwent revision total hip arthroplasty with impaction bone grafting using a cemented stem and were followed up for at least 5 years were enrolled in this study. In all patients, a sufficient amount of fresh frozen bone of good quality was used. When cortical segmental defects were present, peripheral reinforcement with metal mesh and strut allograft was performed. The average follow-up duration was 11.1 (range, 5.3–15.1) years. The clinical and radiographic outcomes were reviewed at the final follow-up.ResultsThe average Harris hip score was 82.5 (range, 79–94), and the average University of California, Los Angeles activity score was 5.6 (range, 4–8) at the final follow-up. Radiographic assessment revealed an average femoral component subsidence level of 0.67 (range, 0.05–2.81) mm. There were no complications, except one case (7.6%) of periprosthetic fracture.ConclusionsImpaction bone grafting using a cemented stem yielded excellent mid-to-long-term outcomes. It is a reliable technique for Paprosky IV femoral bone defects, and even when severe femoral cortical bone defects are present, long-term stability can be obtained using a metal mesh and/or strut allograft.     

Impaction bone grafting in revision hip surgery

We retrospectively reviewed the use of impaction bone grafting with cement for the fixation of femoral and acetabular components in revision hip arthroplasty. Seventy hips formed the basis of the study, with a mean follow-up time of 37 months. Sixty-eight percent of the femurs showed severe bone loss (Endoklinik grades 3 and 4). The mean Harris hip and Merle D'Aubigne Postel scores were 84 and 15.4, respectively. Massive subsidence occurred in only one femoral revision (>10 mm) and cup migration >5 mm in 6 cases. Loosening was seen in 1 revision for sepsis but none for aseptic loosening. Five complications were identified that were related to the surgical technique. We therefore support the use of this technique in revision surgery in patients with extensive bone loss.     

Radiographic and Clinical Outcomes of Modular Tapered Fluted Stems for Femoral Revision for Paprosky III and IV Femoral Defects or Vancouver B2 and B3 Femoral Fractures

BackgroundExtensive femoral bone loss poses a challenge in revision total hip arthroplasty (rTHA). Many techniques have been developed to address this problem including fully porous cylindrical stems, impaction bone grafting, and cementation of long stems, which have had varied success. Modular tapered fluted femoral stems (MTFS) show favorable results. We sought to determine the minimum 2-year radiographic and clinical performance of MTFS in rTHA in a population with extensive proximal femoral bone loss.MethodsOur clinical database was queried retrospectively for all patients who underwent rTHA with an MTFS. We included patients with Paprosky 3 and 4 femoral bone loss and patients with Vancouver B2 and B3 periprosthetic femur fractures. Patients without 2-year follow-up were invited to return to clinic for X-ray evaluation and to complete clinical questionnaires. We assessed distance of stem subsidence and presence of stem fixation on final X-ray. We recorded all-cause revision and survival of the stem at final follow-up.ResultsOne hundred twenty-nine patients were available for follow-up. Average follow-up time was 3.75 years. One hundred twenty-two stems (95%) remained in place at final follow-up. Median subsidence was 1.4 mm (range 0-21). All-cause revision rate was 16.3% (21 patients). Of the hips revised, 10 were for instability, 6 for infection, 1 for aseptic loosening, and 1 for periprosthetic femur fracture. Three were revised for other reasons. The stem was revised in 7 patients (5.4%), and the most common reason for stem revision was infection (5 patients). The other 2 stems were revised for aseptic loosening in a Paprosky 4 femur and periprosthetic femur fracture. Survival of tapered modular fluted stems with aseptic failure as an endpoint was 98.4%. The mean Hip disability and Osteoarthritis Outcome Score, Joint Replacement score at final follow-up was 73, and mean Veterans Rand 12 item health survey physical and mental scores were 32.8 and 52.2, respectively.ConclusionIn patients with Paprosky 3, 4 femoral defects or Vancouver type B2, B3 fractures, modular tapered fluted stems for femoral revision show excellent outcomes at minimum 2-year follow-up.     

No increased stem subsidence after arthroplasty in young patients with femoral head osteonecrosis: 41 patients followed for 1-9 years

BACKGROUND: Poor bone stock in patients with osteonecrosis of the femoral head may be a reason for poor outcome after hip replacement. One way of studying bone quality is to measure implant migration. We thus investigated the clinical and radiographic results of cementless THR in younger patients with femoral head osteonecrosis. PATIENTS AND METHODS: We studied hips in 41 patients (mean age 48 (25-63) years) with a cementless hip arthroplasty after late stage osteonecrosis. Clinical evaluation was by the Harris hip score, the WOMAC score and the SF-36 score. Stem subsidence was measured with the Ein Bild Roentgen Analyse femoral component analysis (EBRA-FCA) at 3, 12, 24, 60, and 72 months after operation. The average duration of follow-up was 7(1-9) years, with less than 2 years for 2 patients. RESULTS: There was no revision of any hip. No radiographic or clinical stem loosening was seen. After 60 months, the cementless stems showed a median subsidence of -0.7 mm (95% CI: -0.9 to -0.2). No femoral osteolysis occurred. Femoral radiolucent lines, all < 1 mm, were seen in 10 hips. At the latest follow-up the Harris hip score was 83 (23-100) points. INTERPRETATION: Our findings for porous-coated stems in patients with femoral osteonecrosis indicate no greater risk of stem subsidence and rate of osteolysis after an average of 7 years follow-up. Thus, we continue to use uncemented stems in younger patients with femoral osteonecrosis. However, continued follow-up will be necessary to evaluate the long-term outcome.     

Massive early subsidence following femoral impaction grafting

The incidence of massive early subsidence (subsidence greater than 10 mm) following impaction grafting of the femur in revision surgery is reported. The first 79 consecutive revision total hip arthroplastics using morselized allograft, polymethyl methacrylate cement, and a double-tapered, polished, collarless stem were reviewed. Nine (11%) of the 79 revision femoral prostheses showed massive subsidence, with another nine hips subsiding to a lesser degree. Further elucidation of the critical factors contributing to the initial stability of the biologic composite is required.     

Femoral impaction grafting in revision hip arthroplasty with irradiated bone

We evaluated the results of femoral impaction grafting with the Exeter stem (Stryker Howmedica Osteonics, Newbury, UK) and irradiated bone-graft. We followed 57 hips for an average of 27 months. Endo-Klinik grading showed 8 grade 1, 22 grade 2, and 27 grade 3 hips. Radiographic analysis revealed cortical repair in 34% and graft incorporation in 39% but no evidence of trabecular remodeling. Moderate subsidence (5-10 mm) occurred in 7 patients (12.5%), and massive subsidence (>10 mm) occurred in 4 patients (7%). Complications included 6 dislocations, 3 periprosthetic fractures, and 2 stem revisions. Impaction grafting with the Exeter system produces satisfactory results for most patients, but a few hips perform poorly, and the reasons for this are unclear. We have concerns about irradiated bone-graft because the characteristic changes of graft remodeling are not seen.     

A preclinical study of stem subsidence and graft incorporation after femoral impaction grafting using porous hydroxyapatite as a bone graft extender

This preclinical in vivo screening study compared bone graft incorporation and stem subsidence in cemented hemiarthroplasty after femoral impaction bone grafting with either morselized allograft bone (n = 5, control group) or a 1:1 mix of allograft and porous hydroxyapatite ceramics (HA) granules (n = 5, HA group). At 14 weeks, there was excellent bone graft incorporation by bone, and the stems were well fixed in both groups. The median subsidence at the cement-bone interface, measured using radiostereometric analysis, was 0.14 and 0.93 mm in the control and HA groups, respectively. The comparable histologic results between groups and good stem fixation in this study support the conduct of a larger scale investigation of the use of porous HA in femoral impaction bone grafting at revision hip arthroplasty.     

Femoral impaction bone allografting with an Exeter cemented collarless, polished, tapered stem in revision hip replacement: a mean follow-up of 10.5 years

Femoral impaction bone allografting has been developed as a means of restoring bone stock in revision total hip replacement. We report the results of 75 consecutive patients (75 hips) with a mean age of 68 years (35 to 87) who underwent impaction grafting using the Exeter collarless, polished, tapered femoral stem between 1992 and 1998. The mean follow-up period was 10.5 years (6.3 to 14.1). The median pre-operative bone defect score was 3 (interquartile range (IQR) 2 to 3) using the Endo-Klinik classification. The median subsidence at one year post-operatively was 2 mm (IQR 1 to 3). At the final review the median Harris hip score was 80.6 (IQR 67.6 to 88.9) and the median subsidence 2 mm (IQR 1 to 4). Incorporation of the allograft into trabecular bone and secondary remodelling were noted radiologically at the final follow-up in 87% (393 of 452 zones) and 40% (181 of 452 zones), respectively. Subsidence of the Exeter stem correlated with the pre-operative Endo-Klinik bone loss score (p = 0.037). The degree of subsidence at one year had a strong association with long-term subsidence (p < 0.001). There was a significant correlation between previous revision surgery and a poor Harris Hip score (p = 0.028), and those who had undergone previous revision surgery for infection had a higher risk of complications (p = 0.048). Survivorship at 10.5 years with any further femoral operation as the end-point was 92% (95% confidence interval 82 to 97).     

No increased stem subsidence after arthroplasty in young patients with femoral head osteonecrosis:41 patients followed for 1–9 years

Background?Poor bone stock in patients with osteonecrosis of the femoral head may be a reason for poor outcome after hip replacement. One way of studying bone quality is to measure implant migration. We thus investigated the clinical and radiographic results of cementless THR in younger patients with femoral head osteonecrosis.

Patients and methods?We studied hips in 41 patients (mean age 48 (25–63) years) with a cementless hip arthroplasty after late stage osteonecrosis. Clinical evaluation was by the Harris hip score, the WOMAC score and the SF-36 score. Stem subsidence was measured with the Ein Bild Roentgen Analyse femoral component analysis (EBRA-FCA) at 3, 12, 24, 60, and 72 months after operation. The average duration of follow-up was 7(1–9) years, with less than 2 years for 2 patients.

Results?There was no revision of any hip. No radiographic or clinical stem loosening was seen. After 60 months, the cementless stems showed a median subsidence of –0.7?mm (95% CI: –0.9 to –0.2). No femoral osteolysis occurred. Femoral radiolucent lines, all < 1?mm, were seen in 10 hips. At the latest follow-up the Harris hip score was 83 (23–100) points.

Interpretation?Our findings for porous-coated stems in patients with femoral osteonecrosis indicate no greater risk of stem subsidence and rate of osteolysis after an average of 7 years follow-up. Thus, we continue to use uncemented stems in younger patients with femoral osteonecrosis. However, continued follow-up will be necessary to evaluate the long-term outcome.     

Vibration-assisted bone-graft compaction in impaction bone grafting of the femur

The complications of impaction bone grafting in revision hip replacement includes fracture of the femur and subsidence of the prosthesis. In this in vitro study we aimed to investigate whether the use of vibration, combined with a perforated tamp during the compaction of morsellised allograft would reduce peak loads and hoop strains in the femur as a surrogate marker of the risk of fracture and whether it would also improve graft compaction and prosthetic stability. We found that the peak loads and hoop strains transmitted to the femoral cortex during graft compaction and subsidence of the stem in subsequent mechanical testing were reduced. This innovative technique has the potential to reduce the risk of intra-operative fracture and to improve graft compaction and therefore prosthetic stability.