Large acetabular bone defects caused by aseptic loosening are common. Reconstruction of large segmental defects can be challenging. Various implants and operative techniques have been developed to allow further acetabular revision in cases where bone stock is poor. Reconstitution of bone stock is desirable especially in younger patients. The aim of the study was to review the clinical and radiological results of hip revision with structural acetabular bone grafts using fresh frozen allograft and cemented components. Between 1990 and 2014, 151 first time revisions for aseptic acetabular loosening with acetabular reconstruction with a fresh frozen structural allograft and cemented components were performed at our hospital. Graft dimensions, number of screws used and socket coverage by the graft were measured on the post-operative AP radiograph. Follow-up radiographs were analysed for socket loosening, quality of graft union, graft and graft resorption.Introduction
Method
A recent paper suggested implanting an uncemented acetabular shell which is 6mm or greater than the native femoral head in total hip arthroplasty (THA) significantly increased the risk of postoperative pain. We retrospectively analyzed 265 Delta ceramic-on-ceramic (DCoC) THA comparing the native femoral head size to the implanted shell and reviewing if the patient suffered with post-operative pain (POP). 265 consecutive THAs were performed using the Corail and Pinnacle prostheses with DCoC bearing. Native femoral head size was calculated retrospectively on pre-operative radiographs using TraumaCad software. All patients were sent questionnaires requesting information on satisfaction, sounds, postoperative pain and complications. Statistical analysis was then undertaken on the data.Introduction
Methods
KAR™ prosthesis was introduced following the success of Corail® femoral stem to tackle difficult revision cases (Paprosky type1, 2a, 2b and 3a). The ARTO group reported a success rate of 94% at 17 years follow-up. Only two independent studies reported similar success rate to date. To analyse the short-term performance of the KAR™ prosthesis used in our unit.Background
Purpose
Cross linked polyethylene (XLPE) has gained popularity as a bearing surface of choice for younger patients despite only medium term results being available for wear rates. Concern remains regarding the long-term stability and durability of these materials. In order to address these issues we present the longest radiological and clinical follow-up of XLPE. Since 1986, we have prospectively studied a group of 17 patients (19 hips) that underwent a cemented Charnley low friction arthroplasty using a combination of 22.225mm alumina ceramic femoral head, a modified Charnley flanged stem and a chemically cross-linked polyethylene cup. We now report the 28 year clinical and radiological results.Introduction
Patients/Materials & Methods
We present the outcome of 297 acetabular revisions using bone grafting and cemented acetabular components in 297 patients, with a mean follow-up of 8 years 3 months (5–20 years). All patients underwent acetabular revision with allograft bone grafting and insertion of cemented acetabular components. Of the 297 patients, 134 patients (45%) were male and 163 (55%) were female. The mean age of undergoing revision surgery with bone grafting was 60 years (25–87 years). The mean weight at revision surgery was 71.9 kg (40–128 kg). Post-operatively, all patients were reviewed regularly in out-patients, where they were examined clinically for any complications and their radiographs were examined for evidence of graft union, radiological lucency and cup migration.Introduction
Methods
Thirty cemented THRs and 13 hybrid THRs were performed through trochanteric osteotomy approach (23), posterior approach (17), Hardinge approach (2) and anterior approach (1). In the cemented group there were 3 cases of superficial wound discharges, 1 recurrent dislocation, 1 complete femoral nerve palsy, 2 cases of neuropraxia and 1 case with persistent hip pain but no cases of infection. In the hybrid group there was one case of partial femoral nerve palsy. None of the patients has undergone any revision surgery till the latest follow up. Radiologically only one case showed aseptic loosening in both femoral and acetabular components, which is not revised as the patient is asymptomatic.
Leg length discrepancy (LLD) following total hip arthroplasty (THA) is a well-known and documented phenomenon. LLD can pose a substantial problem for both the patient and the surgeon. Patient dissatisfaction with LLD after THA is the most common reason for litigation against orthopaedic surgeons. Failure to restore limb length may lead to an unstable hip, whereas over-lengthening may cause low back pain, sciatic nerve palsy and early mechanical loosening. Several intra operative techniques both invasive and non invasive have been reported in the literature to over-come LLD during THA. The accuracy of all the methods that measure from pins anchored into pelvis to point on the greater trochanter may be affected by the inherent variability of the leg position when measurements are made. Bending or dislodging the pins and using of calliper devices can be cumbersome during the THA surgery and can compromise the measurements. Hence we describe a simple, safe and reliable intra operative technique to overcome LLD by using a stout braided suture material tied to the stout Judd pin used to retract the soft tissues in posterior approach. Utilising the routine incision for the posterior approach to the hip, this technique can be easily carried out in primary THA surgery as compared to other techniques used to avoid LLD, which require further incision, and specialised equipment which are time consuming, cumbersome and may not be very secure. This technique of using a suture mark over the Judd pin is simple, inexpensive and easily adaptable.
Introduction: Revision arthroplasty using the impaction grafting technique is an increasingly popular technique. The lost bone stock is replaced rather than substituted with ever increasing amounts of metal. There have been many advances in the understanding of this technique in recent years. It has recently been shown that washing of the graft improves the biomechanical strength, bony ingrowth and biocompatibility of morsellised allograft bone. The aim of this study was to identify the most efficacious method of washing morsellised allograft in the operating room.
Impaction grafting with morsellised allograft is becoming the treatment of choice for revision arthroplasty, especially in the younger patient. The optimum treatment of the graft prior to impaction has not been determined. Some groups wash the graft prior to impaction and others do not. Washing of graft has been shown to enhance bone ingrowth in an animal model, however the reasons for this remain unclear. The aim of this study was to identify any underlying cellular cytotoxicty of fresh frozen allograft bone before and after washing. Paired samples of washed and unwashed morcellised FFH allograft were taken during revision hip arthroplasties. Washing was performed by 4 consecutive rinses in 300ml warmed saline, the bone being filtered between each exchange of saline. Contact cytotoxicity assays involved culture of cell lines in direct contact with bone samples. Quantitative cytotoxicity assays utilised culture media conditioned with the bone samples and subsequent assessment of cell metabolism and viability using both dimethylthiazol (MTT) and neutral red (NR) assays. Assays were performed with human osteoblastic (MG63) and fibroblastic (HSF) cell lines. Nine pairs of samples were analysed. Contact assays demonstrated a clear zone of cellular inhibition around the unwashed bone samples. Quantitative assays were performed in triplicate for each cell type and both MTT and NR assays giving 108 paired assay results. 88.9% of pairs (92/108) showed cytotoxicity in the unwashed sample. No washed samples demonstrated cytotoxicity. When grouped by assay and cell type, analysis of means showed statistically significant differences between washed and unwashed samples in MG63-NR (p=0.0025), HSF-NR (p=0.0004) and MG63-MTT (p=0.008). The difference observed in the HSF-MTT assays did not reach statistical significance (p=0.06). Unwashed FFH allograft can be cytotoxic to human osteoblastic and fibroblastic cell lines in vitro. This suggests that allograft should be washed prior to impaction in order to optimise the biological compatibility.
These results provide a biochemical insight into the bone formation and bone resorption processes during allograft incorporation.
Movement of the limb during computer aided arthroplasty may cause soft tissue impingement on the reference marker(RM) and consequently alter the spatial relationship between RM and bone with resulting inaccuracies in navigation. The purpose of this study was to investigate the effect of different degrees of soft tissue dissection on the stability of reference markers during limb movement. The stability of both one- and two-pin RM systems inserted using three different levels of soft-tissue dissection was analysed in relation to a super-stable RM in fresh cadaver lower limbs. The spatial relationship of the two RMs was analysed using the VectorVision® system (BrainLAB, Germany) during multiple repetitions of four predefined limb movements. All tests were done with RMs inserted in both the distal-anterior femur and distal-lateral femur. Analysis of movements of the test RM in relation to the super-stable RM showed that rotations of less than 0.15o and translations of less than 0.4mm occurred in most test combinations. The combination that showed the greatest instability was when a stab incision was used to insert a pin in the distal/lateral femur (translation 0.73mm+/− 0.05, rotation 0.25o+/− 0.05)(p<
0.001). This instability occurred in both single and double pin RMs(p=0.21). RM pins can be placed in the anterior distal femur through simple stab incisions without resulting in significant soft tissue impingement during limb movement. If pins are placed in the lateral distal femur through stab incisions, impingement may occur from the fascia lata. Release of the fascia lata 1cm either side of the pin prevents significant impingement. Wide skin incision is unnecessary in any location.
Fresh frozen femoral head (FFH) allograft is commonly used in impaction grafting for revision hip arthroplasty and long term success has been demonstrated by some groups. The optimum treatment of the graft prior to impaction has not yet been determined. Some groups wash the graft prior to impaction and others do not. Washing of the graft has been shown to improve bone ingrowth in a bone chamber animal model however the reasons for this remain unclear. The aim of this study was to identify any underlying cellular cytotoxicty of fresh frozen allograft bone before and after washing. Samples of morcellised FFH allograft were taken during revision hip arthroplasties prior to impaction grafting. Paired samples, taken before and after washing were taken from each case. Washing was performed by 4 consecutive washes in 300ml warmed saline, the bone being filtered between each exchange of saline. Cytotox-icity was assessed for all samples using both contact and extract assays. Contact assays involved culture of cell lines in direct contact with bone samples. Extract assays utilised culture media conditioned with bone samples and subsequent quantitative assessment of cell metabolism and viability using both dimethylthiazol (MTT) and neutral red (NR) assays. All assays were performed using both human osteoblastic (MG63) and fibroblastic (HSF) cell lines. Nine pairs of samples were analysed for cytotoxicity using both cell lines. Contact assays demonstrated a clear zone of cellular inhibition around the unwashed bone samples. Extract assays were performed in triplicate for each cell type and both MTT and NR assays giving 108 paired assay results. 88.9% of pairs (92/108) showed cytotoxicity in the unwashed sample. No washed samples demonstrated cytotoxicity. When grouped by assay and cell type, analysis of means showed statistically significant differences between washed and unwashed samples in MG63-NR (p=0.0025), HSF-NR (p=0.0004) and MG63-MTT (p=0.008). The difference observed in the HSF-MTT assays did not reach statistical signifi-cance (p=0.06). In conclusion, we have shown that unwashed FFH allograft can be cytotoxic to human osteoblastic and fibroblastic cell lines in vitro. This suggests that allograft should be washed prior to impaction in order to optimise the biological compatibility.
These results provide a biochemical insight into the bone formation and bone resorption processes during allograft incorporation.
Bone morphogenic proteins (BMPs) are members of the transforming growth factor beta (TGF-beta) family and play a central role in bone formation. These morpho-gens are known to be present in bone matrix however the characteristics of their release during the grafting process has not previously been defined. The aim of this study was to determine the release BMP-7 (osteogenic protein; OP-1) from cancellous allograft that occurs during impaction grafting for revision hip arthroplasty. Forty, 10mm cubes of cancellous bone were accurately cut from the central region of 7 fresh frozen femoral heads. The cubes were centrifuged and washed to remove the marrow contents. The cubes were then individually washed and the fluid assayed for BMP-7 activity using a commercially available enzyme linked immuno-sorbent assay kit (Raybiotech Inc.). The cubes were then divided into 4 groups with samples from each femoral head in each group. Each group was subjected to strain of either 20%, 40%, 60% or 80% using a material testing machine. The cubes were then individually washed again and the wash fluid analysed for BMP-7 activity. BMP-7 activity was found to be present in all groups. Release of BMP-7 was found to increase with increasing strain. At 80% strain the mean concentration of BMP-7 released (830 pg/g) was 58% greater than that released at 60% strain (527 pg/g), 150% greater than the concentration at 40% strain (333 pg/g) and 476% greater than at 20% strain (144 pg/g). The differences between release at 80% and 40% strain and between 80% and 20% strain were statistically significant (p=0.036, p=0.002). Activity of BMP-7 in fresh frozen cancellous allograft bone has not previously been demonstrated. This study shows that the freezing and storage of femoral heads allows some maintenance of biological activity. Furthermore we have shown that BMP-7 may be released in proportion to the strain applied to the bone. This confirms that the process of impaction of bone morsels during revision hip arthroplasty may release BMPs that could aid in the incorporation and remodelling of the allograft.
Pre-operative range of movement (expressed as a percentage of the total ROM of the unaffected side) was 51.5 % (range 23.8–67.2). The mean postoperative ROM was 85.4% (range 56.2 – 99.3). External rotation improved from 41.7% (range 23.5 – 81.5) of the unaffected side preoperatively to 77.7% (range 44.1 – 105.3) at final review. Abduction improved from 47.4 % (range 23.3 – 70.6) to 85.4% (range 49.7 – 100) and forward flexion improved from 59.1% (range 33.5 – 73.9) to 90o (range 64.3 – 100.6). No patients required further manipulation.