Post-traumatic osteoarthritis (PTOA) is a subset of osteoarthritis, which occurs secondary to traumatic joint injury which is known to cause pathological changes to the osteochondral unit. Articular cartilage degradation is a primary hallmark of OA, and is normally associated with end-stage disease. However, subchondral bone marrow lesions are associated with joint injury, and may represent localized bone microdamage. Changes in the osteochondral unit have been traditionally studied using explant models, of which the femoral-head model is the most common. However, the bone damage caused during harvest can confound studies of microdamage. Thus, we used a novel patellar explant model to study osteochondral tissue dynamics and mechanistic changes in bone-cartilage crosstalk.

Firstly, we characterized explants by comparing patella with femoral head models. Then, the patellar explants (n=269) were subjected to either mechanical or inflammatory stimulus. For mechanical stimulus 10% strain was applied at 0.5 and 1 Hz for 10 cycles. We also studied the responses of osteochondral tissues to 10ng/ml of TNF-α or IL-1β for 24hrs.

In general the findings showed that patellar explant viability compared extremely well to the femoral head explant. Following IL-1β or TNF-α treatment, MMP13, significantly increased three days post exposure, furthermore we observed a decrease in sulfate glycoaminoglycan (sGAG) content. Bone morphometric analysis showed no significant changes. Contrastingly, mechanical stimulation resulted in a significant decrease sGAG particularly at 0.5Hz, where an increase in MMP13 release 24hrs post stimulation and an upregulation of bone and cartilage matrix degradation markers was observed. Furthermore, mechanical stimulus caused increases in TNF-α, MMP-8, VEGF expression.

In summary, this study demonstrates that our novel patella explant model is an excellent system for studying bone-cartilage crosstalk, which responds well to both mechanical and inflammatory stimulus and is thus of great utility in the study of PTOA.

Introduction and Objective

Traditionally, osteoarthritis (OA) has been associated mostly with degradation of cartilage only. More recently, it has been established that other joint tissues, in particular bone, are also centrally involved. However, the link between these two tissues remains unclear. This relationship is particularly evident in post-traumatic OA (PTOA), where bone marrow lesions (BMLs), as well as fluctuating levels of inflammation, are present long before cartilage degradation begins. The process of bone-cartilage crosstalk has been challenging to study due to its multi-tissue complexity. Thus, the use of explant model systems have been crucial in advancing our knowledge. Thus, we developed a novel patellar explant model, to study bone cartilage crosstalk, in particular related to subchondral bone damage, as an alternative to traditional femoral head explants or cylindrical core specimens. The commonly used osteochondral explant models are limited, for our application, since they involve bone damage during harvest. The specifics aim of this study was to validate this novel patellar explant model by using IL-1B to stimulate the inflammatory response and mechanical stimulation to determine the subsequent developments of PTOA.

Low back pain (LBP), caused by intervertebral disc (IVD) degeneration represents one of the most significant socioeconomic conditions facing Western economies. Novel regenerative therapies, however, have the potential to restore function and relieve pain. We have previously shown that stimulation of adipose-derived stem cells (ASCs) with growth differentiation factor-6 (GDF6) promotes differentiation to nucleus pulposus (NP) cells of the IVD, offering a potential treatment for LBP. The aims of this study were to i) elucidate GDF6 cell surface receptor profile and signalling pathways to better understand mechanism of action; and (ii) develop a microparticle (MP) delivery system for GDF6 stimulation of ASCs. GDF6 receptor expression by ASCs (N=6) was profiled through western blot, immunofluorescence (IF) and flow cytometry. Signal transduction through Smad1/5/9 and non-Smad pathways following GDF6 (100ng/ml) stimulation was assessed using western blotting and confirmed using pathway specific blockers and type II receptor sub-unit knockdown using CRISPR. Release kinetics of GDF6 from MPs was calculated (BCA assay, ELISAs) and ASC differentiation to NP cells was assessed. BMPR profiling revealed high BMPR2 expression on ASCs. GDF6 stimulation of ASCs resulted in significant increases in Smad1/5/9 and Erk phosphorylation, but not p38 signalling. Blocking GDF6 signalling confirmed differentiation to NP cells required Smad phosphorylation, but not Erk. GDF6 release from MPs was controlled over 14days in vitro and demonstrated comparable NP-like differentiation to exogenous GDF6 delivery. This study elucidates the signalling mechanisms responsible for GDF6-induced ASC differentiation to NP cells and also demonstrates an effective and controllable release vehicle for GDF6.

Background

Currently, there is a focus on the development of cell based therapies to treat intervertebral disc (IVD) degeneration, particularly for regenerating/repairing the central region, the nucleus pulposus (NP). Recently, we demonstrated that GDF6 promotes NP-like differentiation in mesenchymal stem cells (MSCs). However, bone marrow- (BM-MSCs) and adipose- (Ad-MSCs) showed differential responses to GDF6, with Ad-MSCs adopting a more NP-like phenotype. Here, we investigated GDF6 signalling in BM-MSCs and Ad-MSCs, with the aim to improve future IVD stem cell therapies.

Background

Stem cell therapy has been suggested as a potential regenerative strategy to treat IVD degeneration and GDF6 has been shown to differentiate adipose-derived stem cells (ASCs) into an NP-like phenotype. However, for clinical translation, a delivery system is required to ensure controlled and sustained GDF6 release. This study aimed to investigate the encapsulation of GDF6 inside novel microparticles (MPs) to control delivery and assess the effect of the released GDF6 on NP-like differentiation of human ASCs.

Background

Signalling by growth differentiation factor 6 (GDF6/BMP13) has been implicated in the development and maintenance of healthy NP cell phenotypes and GDF6 mutations are associated with defective vertebral segmentation in Klippel-Feil syndrome. GDF6 may thus represent a promising biologic for treatment of IVD degeneration. This study aimed to investigate the effect of GDF6 in human NP cells and critical signal transduction pathways involved.

Despite a lack of long-term follow-up, there is an increasing trend towards using femoral heads of large diameter in total hip replacement (THR), partly because of the perceived advantage of lower rates of dislocation. However, increasing the size of the femoral head is not the only way to reduce the rate of dislocation; optimal alignment of the components and repair of the posterior capsule could achieve a similar effect.

In this prospective study of 512 cemented unilateral THRs (Male:Female 230:282) performed between 2004 and 2011, we aimed to determine the rate of dislocation in patients who received a 22 mm head on a 9/10 Morse taper through a posterior approach with capsular repair and using the transverse acetabular ligament (TAL) as a guide for the alignment of the acetabular component. The mean age of the patients at operation was 67 years (35 to 89). The mean follow-up was 2.8 years (0.5 to 6.6). Pre- and post-operative assessment included Oxford hip, Short Form-12 and modified University of California Los Angeles and Merle D’Aubigne scores. The angles of inclination and anteversion of the acetabular components were measured using radiological software. There were four dislocations (0.78%), all of which were anterior.

In conclusion, THR with a 22 mm diameter head performed through a posterior approach with capsular repair and using the TAL as a guide for the alignment of the acetabular component was associated with a low rate of dislocation.

Cite this article: Bone Joint J 2014;96-B:1202–6.

Hip replacement is a very successful operation and the outcome is usually excellent. There are recognised complications that seem increasingly to give rise to litigation. This paper briefly examines some common scenarios where litigation may be pursued against hip surgeons. With appropriate record keeping, consenting and surgical care, the claim can be successfully defended if not avoided. We hope this short summary will help to highlight some common pitfalls. There is extensive literature available for detailed study.

Clinical success of total knee arthroplasty is correlated with correct orientation of the components. Controversy remains in the orthopaedic community as to whether the intramedullary or extramedullary tibial alignment guide is more accurate in the tibial cut.

Is there any difference between intramedullary and extramedullary jigs to achieve better accuracy of the tibial components in total knee replacements?

A retrospective study done on 100 patients during the time period 2007 to 2010. The 100 knee replacements were done by the same surgeon, where 50 patients had the intramedullary tibial alignment guide and the other 50 had the extramedullary one. The tibiofemoral angle was measured pre-operatively as well as post operatively, the tibial alignment angle was measured post operatively then the results were statistically analysed using the SPSS.

There was no significant difference between both groups regarding the tibial alignment angles. Both techniques proved accurate in producing an acceptable post operative tibial component alignment angle. We recommend orthopaedic surgeons choose either technique knowing that accuracy levels are similar.

The debate between intramedullary and extramedullary tibial cutting jigs/guides/ devices continues and most orthopaedic surgeons will use their preferred technique and will continue to achieve good post operative results as we have found in our centre. Our study is rare due to the fact we have a single surgeon performing both techniques, therefore controlling for any surgical experience or operating technique differences.

Introduction: Trochanteric osteotomy provides excellent exposure to perform hip replacement surgery. In the UK, 5.9% of primary hip replacements are performed using an osteotomy. Trochanteric non union is one of the complications of this approach. The aim of this study was to investigate the role of release of posterior trochanteric soft tissue release on the incidence of trochanteric non-union.

Method: We present the results of 100 patients who underwent primary cemented total hip replacement at our centre using the biplanar, intracapsular osteotomy. Group A (50 patients) had received a posterior trochanteric soft tissue release as part of the approach and Group B (50 patients) had not. Patients were followed up clinically and radiologically.

Results: In group A the trochanteric non union rate was 12% and in group B 2% (p< 0.05). According to the Hodgkinson’s classification of trochaneric non-union, all the non-unions in group A were grade 3 (> 1.5 cm migration) and group B was grade 2 (< 1.5cm migration).

Discussion: The two different techniques were examined on cadaveric specimens and it was noted that the obturator externus tendon was consistently cut as a part of the posterior soft tissue release. We conclude that this important structure should not be released as part of this approach to hip replacement. Obturator externus is an important adductor of the trochanter and preserving it decreases the incidence of trochanteric non-union.

Introduction: Extensive bone loss associated with revision hip surgery is a significant orthopaedic challenge. Acetabular reconstruction with the use of impaction bone grafting and a cemented polyethylene cup is a reliable and durable technique in revision situations with cavitatory acetabular bone defects. Slooff et al. (1996) reported the use of cancellous graft alone. Brewster et al. (1999) morselised the whole femoral head after removal of articular cartilage. This paper asks, is it really necessary to use pure cancellous graft?

Methods: 42 acetabular revisions using impacted morselised bone graft without removal of articular cartilage and a cemented cup were studied retrospectively. The mean follow up was 2.6 years (1–5yrs). Clinical and radiographic assessment was made using the Oxford Hip score, Hodgkinson’s criteria (1988) for socket loosening and Gie classification (1993) for evaluation of allograft consolidation and remodelling.

Results: 40(95%) sockets were considered radiologically stable (Type 0, 1, 2 demarcations). 2(5%) sockets were radiologically loose (Type 3 demarcation). There was no socket migration in our series. 27(64%) cases showed good trabecular remodelling (grade 3). 12(29%) cases showed trabecular incorporation (grade 2). Only 3(7%) cases showed poor allograft incorporation (grade 1). Average pre operative Oxford hip score was 41 and postoperative hip score was 27. There have been no socket re-revisions (100% survival) at an average of 2.6 years.

Conclusion: Early radiological and clinical survival results with retaining articular cartilage of femoral head allograft are similar and comparable to other major studies for acetabular impaction bone grafting in revisions. Minimal loss of allograft mass is 40% in obtaining pure cancellous graft. When there is a limited supply and demand of allograft, saving up to 40 % of the material is a valuable and cost effective use of scarce resources.

Introduction: The purpose of this study was to review the results of revision total hip replacement, using cement, done by a single surgeon in a tertiary referral centre. 164 patients underwent revision hip surgery for aseptic loosening, infection or recurrent dislocation.

Methods: 95 patients had a one stage revision, 25 patients had two stage revisions and the remainder had either the stem or socket revised. 10 patients had application of a PLAD for recurrent dislocation. Structural and morselized bone grafting was carried out in patients with extensive bone loss. 46 patients had morselized impaction bone grafting to the acetabulum. The first hundred patients with revision of both components and minimum follow up of twelve months were reviewed. Patients were routinely followed up in the clinic and assessed using the Oxford Hip Score and Merle D’Abigne scores for pain, function and range of movements. Radiographs were assessed for any demarcation or loosening.

Results: The mean age at surgery was 69.99 years (36ys to 95yrs). The mean follow up was 25 months (12 to 60 months). There were 5 dislocations, 2 wound dehiscence, 3 DVT’s and 2 deep infections in the whole group. There were 2 dislocations, 2 DVT, 1 wound dehiscence and 1 infection in the study group. The preoperative scores were available for 83 patients and the average scores for pain, function and range of movements were 3.2, 2.8 and 1.6 respectively. The average scores at the latest follow up were 5.08, 4.2 and 4.0. The mean Oxford Hip scores were 26.65. X-rays showed no demarcation in the acetabulum in 88 patients and in the femur in 92 patients. The trochanter was united in 72 patients. In 13 patients the trochanter had migrated more than 1 cm.

Conclusion: Revision total hip replacement using cement has shown good results in the short term. Cemented revisions are safe, reliable and also cost effective.

Aim: To determine if it is possible to predict the pattern of socket failure from the first post-operative x-rays.

Methods: A retrospective review was performed of patients undergoing revision hip surgery for aseptic socket loosening. An assessment was made of the pattern of failure and socket migration. Operative details of bone defects and reconstructions required were noted.

Results: 55 patients were identified with an average age of 46.2 years at primary surgery. The average socket survival was 16.14 years. There was no association between the patient’s age or original diagnosis and the duration of socket survival.

Supero-medial migration was seen in 27 (49%) of cases, demarcation without migration was seen in 18 cases (33%) and supero-lateral migration was seen in 7 (13%) cases. There were 2 (4%) socket fatigue fractures due to wear. There was 1 (2%) patient with a worn socket and no loosening.

Reconstruction was achieved by impaction bone grafting alone in 25 cases, IBG and a block allograft in 9 cases, cement alone in 8 cases and IBG with a rim mesh in 4 cases.

In cases where the supero-lateral margin of the socket was covered by host bone, failure always occurred by demarcation alone or in association with supero-medial migration. Rim defects significant enough to require reconstruction were seen in only 4 of these 45 patients (9%). Failure by supero-lateral migration was only seen in the cases of DDH where the socket was left uncovered or where the socket had fractured.

Conclusions: In this young age group series cemented acetabular components performed well, failed predictably and were relatively straightforward to reconstruct.

The pattern of socket failure can be reliably predicted from the original post-operative x-rays. Care should be taken to ensure adequate supero-lateral coverage in order that demarcation and migration leave an intact rim for reconstruction.

Introduction: Recurrent Instability of the hip remains a difficult problem to treat successfully. The Posterior Lip Augmentation Device (PLAD) is a useful option where there is no gross mal-orientation of the components.

Methods: A retrospective single surgeon review was performed to identify patients who had undergone application of a PLAD to treat recurrent instability. Patients with less than 12 months follow up were excluded.

Results: 14 patients were identified with an average age of 75.5 years (Range 59 – 90 years). There were 7 cases of trochanteric non-union as a result of previous surgery. The mean follow up was 26 months (Range 13 – 41 months). In 13 patients there have been no further instances of dislocation. 1 patient went on to dislocate again and has now undergone a socket revision.

Conclusion: Application of the Posterior Lip Augmentation Device is a well tolerated procedure with very favourable success rates (93%). Given the limited morbidity and short operating time associated with this surgical option it provides a predictable outcome in cases where the original components are well orientated and securely fixed.

Introduction: We performed a retrospective case control study in 80 patients who under went revision hip surgery at our unit.

Methodology: Group A (40 patients), received tranexamic acid and intra-operative cell salvage. Group B (40 patients) a matched control did not receive these treatments. Each group was divided into 4 sub groups; revision of both components, revision of components + bone grafting, revision acetabular component +/− bone grafting and revision femoral component +/− bone graft.

Results: In group A the total number of units transfused was 139 compared to 52 in group B. This represents a reduction in blood usage of 37%. The mean amount of blood transfused from cell salvage in each group was 858mls, 477mls, 228mls and 464mls. There was a significant difference in the amount of blood returned between the groups (p< 0.0001). In the control group 37 patients needed transfusion, in the study group 22 (p< 0.0001). At our unit a cost analysis calculation has shown total revenue saving of £88,000 and a potential saving throughout the trust of £316,688 per year.

Discussion: To our knowledge this is the first study to examine the use of cell salvage and tranexamic acid in revision hip surgery. Our results show that a significant reduction in blood transfusion can be made using this technique. It is vital that blood conserving strategies are developed so that future revision surgery can continue.

Introduction: Revision hip arthroplasty places a significant burden on hospital resources. Huge pressure is being placed on the orthopaedic community to alter practices with respect to implant selection and bearing surfaces in order to try to reduce the likelihood of revision due to aseptic socket loosening. To date there is little clinical evidence to support these changes.

Aim: To review the case mix requiring revision surgery at a specialist arthroplasty unit in order to identify the common reasons for failure of primary arthroplasties.

Methods: A retrospective single surgeon review was performed to identify patients who had undergone revision hip surgery over the study period. The reasons for revision were identified for all cases. Particular attention was paid to the cases with aseptic socket loosening to determine the time to revision for these cases.

Results: 176 revision procedures were performed between October 2001 and May 2005. In 74 (42%) cases aseptic socket loosening was identified (average socket survival 15.4 years). In 16 cases this was the sole cause for revision. In 58 cases the femoral component was also loose. 102 (58%) cases were performed for other reasons. Dislocation was the cause in 14%, femoral component loosening in 20%, infection in 18% and fracture in 6%. Aseptic loosening of cemented sockets less than 10 years old was only seen in 7 (4%) cases.

Conclusions: Aseptic loosening of cemented sockets less than 10 years old was the least common cause of revision in this series. Cemented polyethylene acetabular components continue to provide a satisfactory bearing surface on the acetabular side of total hip arthroplasties. We recommend caution when interpreting the information provided with new products with respect to the benefits of different fixation and bearing surfaces for the majority of patients.

Our study evaluated the reliability of the Crowe and Hartofilakidis classification systems for developmental dysplasia of the hip in adults. The anteroposterior radiographs of the pelvis of 145 patients with 209 osteoarthritic hips were examined twice by three experienced hip surgeons from three European countries and the abnormal hips were rated using both classifications. The inter- and intra-observer agreement was calculated.

Interobserver reliability was evaluated using weighted and unweighted kappa coefficients and for the Crowe classification, among the three pairs there was a minimum kappa coefficient with linear weighting of 0.90 for observers A and C and a maximum kappa coefficient of 0.92 for observers B and C. For the Hartofilakidis classification, the minimum kappa value was 0.85 for observers A and B, and the maximum value was 0.93 for observers B and C. With regard to intra-observer reliability, the kappa coefficients with linear weighting between the two evaluations of the same observer ranged between 0.86 and 0.95 for the Crowe classification and between 0.80 and 0.93 for the Hartofilakidis classification.

The reliability of both systems was substantial to almost perfect both for serial measurements by individual readers and between different readers, although the information offered was dissimilar.

Recently, there has been a reluctance to perform hip arthrodesis. The number of patients requiring the conversion from hip arthrodesis to arthroplasty has also decreased. We present the functional results following conversion of hip arthrodesis to total hip arthroplasty at a specialist hip centre.

76 patients who underwent conversion of hip arthrodesis to total hip arthroplasty between 1963 and 2000 at the Centre for Hip Surgery, Wrightington Hospital, were included in this retrospective study. 9 patients died of unrelated causes and 7 patients were lost to follow up. The functional scoring was performed using the Merle d’Aubigné and Postel score.

The mean age at the time of surgical hip arthrodesis was 16.7 years and at the time of conversion was 48.7 years. Back pain is the most common indication for the conversion. All the patients were pleased with the clinical outcome following conversion to Arthroplasty. 6 patients had postoperative complications. The mean Merle d’Aubigné and Postel score increased from 8.97 to 13.46 at the latest follow-up. The mean wear rate was 0.06 mm/year. Survival of hip arthroplasty was 92.78 % at 18 years.

Conclusion: Our series demonstrates good outcome and patient satisfaction and high survival of the arthroplasty following the conversion from arthrodesis. Hip arthrodesis could be considered as a holding procedure in selected group of young patients with a later successful conversion to arthroplasty.

To determine socket survivorship in DDH based on the severity of hip dysplasia, we carried out a retrospective study of 283 cemented total hip replacements carried out at Wrightington. The hips were classified according to the Crowe and Hartofilakidis classifications. Revision was used as the end point for prosthetic survivorship. The results were analysed statistically using SPSS for Windows

The mean age at time of surgery was 42.6 years with a mean follow-up of 15.7 years. The acetabulum was grafted in 46 cases. The commonest cause for revision was aseptic loosening of the acetabular component (88.3%). 254 procedures were carried out through a transtrochanteric approach with a direct lateral approach used for the remaining mildly dysplastic hips. At 10 years 5.3% of dysplastic, 14.8% of low dislocation and 51.1 % of high dislocation hips were revised.. At 10years 6% of Crowe Type1, 8.5% of Type2, 25.5% of Type3 and 39.2% of Type4 hips were revised. At 20 years 24% of dysplastic, 45% of low dislocation and 88% of high dislocation hips were revised. At 20years 27.3% of Crowe Type1, 29.3% of Type2, 63.3% of Type3 and 84.4% of Type4 hips were revised. The 20 year survival of patients less than 50 years of age at the time of surgery was 61% as compared to 92% survival in patients more than 50 years of age. The mean age of patients in the revised group was 35 years as compared to 45 years in the non-revised group.

Conclusion: This study demonstrates satisfactory results in dysplastic hips following cemented total hip replacements. With increasing severity of hip dysplasia there is a higher rate of premature failure of the acetabular component. There is adverse correlation between age and survival of the acetabular component. There is a dramatic increase in cup failure between 10 and 20 years.

Patients undergoing total hip replacement (THR) often require further orthopaedic surgery including other primary lower limb joint replacements and revision surgery in their lifetime. We analysed the 10-year data of 552 patients who underwent primary total hip replacement between April 1991 and March 1992 at our institute. Data were available for all patients before the index operation. 77% of patients attended their 5-year review and 67% attended their 10-year review. 233 (42%) had had or subsequently had the opposite hip replaced. 30 patients (5%) had a knee replaced and 19 (3%) had both knees replaced. 4.4% underwent revision surgery.

Conclusion: nearly half the total number of these patients will in due course require the opposite hip replaced. 13% will need another major joint surgery (ie revision or TKR). At £6138 for a primary THR and £8500 for revision THR, and the cost of radiographs (£60) and follow-up appointment (£60), the approximate cost implications on a conservative estimate are £13,000.000. These factors including cost implications and human resource requirements will have significant influence on future planning of health care trusts.