Follow-up of arthroplasty varies widely across the UK. The aim of this NIHR-funded study was to employ a mixed-methods approach to examine the requirements for arthroplasty follow-up and produce evidence-based and consensus-based recommendations. It has been supported by BHS, BASK, BOA, ODEP and NJR.

Four interconnected work packages have recently been completed: (1) a systematic literature review; (2a) analysis of routinely collected National Health Service data from four national data sets to understand when and which patients present for revision surgery; (2b) prospective data regarding how patients currently present for revision surgery; (3) economic modelling to simulate long-term costs and quality-adjusted life years associated with different follow-up care models and (4) a Delphi-consensus process, involving all stakeholders, to develop a policy document to guide appropriate follow-up care after primary hip and knee arthroplasty.

We will present the following Recommendations:

For ODEP10A∗ minimum implants, it is safe to disinvest in routine follow-up from 1 to 10 years post non-complex hip and knee replacement provided there is rapid access to orthopaedic review

Introduction

Reverse hybrid total hip replacement (THR) offers significant theoretical benefits but is uncommonly used. Our primary objective was to evaluate implant survival with all cause revision and revision for aseptic loosening of either component as endpoints.

Background

Acute pain following total knee replacements (TKRs) is associated with higher peri-operative opiate requirements and their side effects, longer hospital stay and lower patient satisfaction (Petersen 2014). It may also be associated with higher rates of chronic pain at 1 and 5 years (Beswick 2012). We present a novel technique using combination of Local Infiltration Anaesthesia (LIA) with PainKwell infusion system (Bupivacaine 0.5 @ 4mls and 6mls/hr) to improve pain management following TKRs.

In the UK, the posterior approach (PA) and direct lateral approach (DLA) are the most common total hip arthroplasty (THA) procedures. Few studies however, have compared the subsequent functional outcomes. This exploratory study aimed to examine the effect of PA and DLA approaches on post-operative hip kinematics, strength and hip muscle cross-sectional area (CSA), compared to healthy controls.

Participants comprised of 15 cases in the DLA group, > 12 month post-operatively, (ten male, age 68.9+/-5.5 years, BMI 26.9+/-3.0), 13 cases in the PA group (six male; age 72.9+/-6.9 years, BMI 27.1+/-3.6) and 11 age/BMI-matched healthy control participants. All participants underwent 3D kinematic (Vicon, Oxford, UK) and kinetic (AMTI, USA) analysis whist performing self-selected and fast walking as well as sit-to-stand and stand-to-sit. Isometric dynamometry was performed (Biodex Medical systems, USA) for all major muscle groups around the operated hip, and a subset of five participants (three DLA v two PA) underwent “slice encoding for metal artefact correction” (SEMAC) MRI imaging to measure muscle CSA. Patient-reported outcome measures were collected.

Both post-operative surgical groups exhibited altered gait, particularly in limited hip extension, compared to the control participants. The DLA group demonstrated forced hip extension matching controls only under fast walking conditions while the PA group did not achieve hip extension. Both surgical approaches achieved high PROMs scores.

The PA group were weaker for all strength activities tested, whereas the DLA cases demonstrated similar hip strength to controls. SEMAC imaging revealed reduced CSA for those muscles dissected during surgery, compared to the contralateral side.

This exploratory study demonstrated small but measurable differences between surgical approaches for muscle CSA, hip strength of major hip muscle groups and a number of gait variables, although both approaches produce satisfactory functional outcomes for patients after surgery.

Background

Hip arthroplasties are associated with high postoperative pain scores. In some reports, moderate to severe pain was 58% on the first day postoperatively in total hip replacements (THRs). Several techniques are currently used at our institution to tackle acute pain following THRs. These include: 1) Spinal anaesthetic (SA) with Diamorphine only; 2) General anaesthetic (GA) only; 3) SA with local infiltration anaesthetic mixture 1 (LIA1,). Mixture 1 consisted of ropivacaine, adrenaline, and ketorolac; 4) SA with LIA mixture 2 (LIA2). Mixture 2 consisted of bupivacaine and adrenaline; 5) SA with LIA1 and PainKwell pump system. In this study we report on the techniques of acute pain control following THR at our regional centre for elective primary THRs.

Background

Pain control following knee replacement (TKR) surgery is often poor. Moderate to severe pain is often reported in the first 48 hours following surgery requiring opiate analgesia. The Local Infiltration Anaesthetic (LIA) technique has been described as a method to reduce post operative pain. In this study we report on our experience using LIA in addition to the PainKwell system (Peak Medical) of continuous infusion intra-articularly, of 0.25% bupivacaine at 4–5 mls/hour for 48 hours post surgery. The PainKwell catheter is placed in the knee joint during surgery.

Background

The factors influencing normal spine curvature in midlife are unknown. We performed an MR and plain radiograph study on well characterised, unselected twin volunteers from the TwinsUK register (www.twinsuk.ac.uk) to determine the relative contributions of genetic and environmental factors to spine curve.

Introduction

During broach preparation and implant insertion of the proximal femur the surgeon may be able to use audible pitch changes to judge broaching adequacy and implant position. The aim of this study was to analyse the sound produced and explain the sound spectra using acoustic physics.

Purpose of the Study

This study aims at investigating the effect of application time of bone cement on the cement-bone interface strength in two types of commercially available bone cements, Cement-A and Cement-B.

Our aim was to highlight that there is a sub-group of patients with disabling symptoms after leg lengthening at primary hip replacement who benefit from revision surgery.

Most patients with an over lengthened limb after total hip arthroplasty are either asymptomatic or find it an inconvenience which can often be treated with a shoe raise. A minority, however, find this severely debilitating, patients describing that the leg “feels long”, with pain felt around the hip, difficulty sitting and limited function. It is this sub-group of patients that we feel benefit from revision surgery to equalise leg lengths.

We report on 8 cases (6 female; 2 male) that underwent revision surgery for leg lengthening over a 7 year period . The mean leg length difference was 14.3mm (range 10-20mm). Five patients had revision of the stem only and the remaining 3 both cup and stem. Time to revision varied from 8 months to 3 years. We outline our method of radiological measurement of leg length after total hip arthroplasty, using the centre of hip rotation as the reference point. Individual cases are discussed with radiographs highlighting the typical clinical features and this radiological technique.

All patients reported an immediate improvement in their symptoms following revision surgery and have remained pleased with the outcome at their latest follow up.

Leg lengthening as a result of total hip arthroplasty is well recognised but its treatment remains controversial. There is a sub-group of patients who are particularly sensitive to over lengthening, often of short stature. We reiterate that this revision surgery is beneficial to the patient with a lengthened leg ONLY if they have significant symptoms and limitation of function. Our small series emphasises the need to recognise this group of patients who can achieve a successful outcome after revision surgery.

PURPOSE: To determine the capability of fellowship trained Orthopaedic Trauma surgeons to predict union or non-union of femoral and tibial shaft fractures.

METHODS: A series of 50 patients with femur or tibia shaft fractures were evaluated. Patients were prospectively followed at 2,6,12, and 18 weeks after surgical intervention. At each interval surgeons evaluated factors related to fracture healing on AP and lateral radiographs and predicted the probability of union on a visual analog scale. Union was defined as radiographic evidence of healing three of four cortices, no tenderness with palpation of the fracture site, and full weight bearing without the use of assistive devices.

RESULTS: Eight patients missed initial visits or were lost to follow-up, making for a total of 42 patients that were included in the results. Average patient age was 31 years. Eighty-one percent of the patients went onto union (N=34) and 19% went onto nonunion (N=8). Early clinical prediction for nonunion at 2 weeks had a sensitivity of 50%, a specificity of 91%, a positive predictive value (PPV) of 57%, and a negative predictive value (NPV) of 89%. At 6 weeks, there was a sensitivity of 75%, a specificity of 100%, a PPV of 100%, and a NPV of 94%. One patient treated with intramedullary nailing was 15 years old and despite minimal callous formation the physician incorrectly predicted future union given the young age. The other patient had a severely comminuted femur fracture and required a quad cane to ambulate and should perhaps have been predicted to go onto nonunion. At 12 and 18 weeks, sensitivity, specificity, PPV, and NPV were both 100%.

CONCLUSIONS: Fellowship trained orthopaedic trauma surgeons at 6-week follow-up can predict union with a sensitivity of 75% and specificity of 100% and a PPV of 100%. Early clinical prediction at 6 weeks can be used to provide the patient with a secondary intervention such as a bone graft or bone stimulator and avoid months of delay.

Hip arthroplasty has its true genesis in 1962 when the Charnley Total Hip was first implanted. The system comprised a stainless steel femoral stem with fixed 22,225mm head articulating against an all polyethylene acetabular cup. Both components were fixed in position with acrylic bone cement. There have been a number of changes in design, materials and surgical technique but the essential concept remains the same. The system was widely used by both senior and junior surgeons. Numerically implantations peaked at ~45,000 per annum in the late1980’s and is still at around ~25,000 per annum in the mid 2000’s. Geographically the system was used in all five continents. Patients varied widely both in age, activity, and diagnosis. It would therefore seem an appropriate vehicle to examine the variations in results of total hip replacement by patient profile, geography, and era of implantation.

A search was carried out on the US NCBI website for publications reporting on results with the Charnley system up to the end of 2002, and which comprised a follow-up of more than 10 years, and gave survivorship data. This resulted in 28 papers with 14 countries of origin available for review. For all studies basic data such as age and diagnosis, range implantation dates, likely specific design of prosthesis, origin of study and number in study was either reported or could be deduced. A ten year survivorship was reported in 16 studies for stem and cup and 7 for stem only. If the longest follow-up was considered for each study then 18 reported on stem and cup (9392 hips, implanted 1962–92) and 15 on stem only (4243 hips, implanted 1966–91). A total of 11 studies had four of more points on a survivorship curve, seven with stem and cup, four with stem only.

There are a number of points of interest in this data. The first is that with one exception the performance is remarkably consistent as shown by the survivorship curves. There is no significant difference in the survival rates from different centres, countries, and with implantation dates ranging from 1962 through to 1992. Secondly, there appears to have been little or no change in the average age of patients with implant date. There is some evidence to indicate from the 10 year data that failure rate per year is lower in older patients but does not seem to be affected by implantation date. The latter despite the fact that both surgical technique and component design changed over the 30 year implantation period. A further observation is that the failure rate per year is lower in studies with greater numbers of patients.

The general conclusion from this review is that the Charnley Total Hip is remarkably consistent in its performance both over time and location of implantation. Its performance also seems to have been affected very little by changes in technique or design.

Introduction: Reported incidence of dislocation following dislocation of hip replacements varies from less than 1% to 8%, the majority (59%) being in the first 3 months and 77% within a year. Recurrent dislocation of total hip arthroplasty is a serious problem for both patient and surgeon. Revision of the components does not guarantee success and there is significant comorbidity associated with major revision surgery. Early techniques of cup augmentation were complicated by screw and augment failure, hence cup augmentation evolved into a low profile polyethylene wedge with a separate metal backing and five screw fixation called the Posterior Lip Augmentation device (PLAD).

Methods: 33 patients in Leeds and Inverness underwent PLAD placement between 1995 and 2000. They were followed up at a minimum of 5 years postoperatively (5–9 years). Where patients had died the cause of death and status of the PLAD at time of death was determined from the notes.

Results: The mean age at time of PLAD insertion was 73 years(43–94). The longest survival was 102 months, the shortest 8 days. Of the 33 patients undergoing PLAD insertion, 3 were lost to follow up, 13 had died by the time of follow up, 7 had been revised and 10 had survived revision free.

Discussion: When considering the revision as an end point, PLAD insertion compares favourably with total revision. As shown by the mortality of the patients in the cohort, a less invasive option for the patient with significant comorbidities is useful to have in the surgical armamentarium.

Introduction: We present our results of the first 413 Charnley arthroplasties performed by and under the supervision of the senior surgeon, using the posterior approach.

Methods: This is a prospective study of clinical and radiographic outcomes. Four hundred and thirteen hip replacements were performed in 380 patients (215 female and 165 male) between 1992 and 1996. The mean age at the time of primary surgery was 67 years (28 – 91 years).

Results: The primary aetiology in 297 of the hips was osteoarthritis. Eighty-two had rheumatoid arthritis.

Eleven patients (3%) had one or more episodes of dislocation.

There were 22 revisions. Three of the revisions were carried out for infection, and a further 2 for recurrent dislocation. Aseptic loosening was the cause of failure in the remaining 17.

Thirty three patients (36 hips, 9%) could not be traced at the time of the final follow-up. There was significant and maintained improvement in pain and function scores.

One hundred and thirty eight patients (146 hips) had died at the time of the final follow-up.

The best and worst case survivorship figures at 10 years were 93 +/− 2% and 83 +/− 2%, and those at 14 years were 88 +/− 4% and 78 +/− 4%, respectively, with revision for any reason as the end-point.

Discussion: Excellent results for the Charnley hip are possible using the posterior approach and surgeons of varying experience. The results presented compare favourably with the published data and confirm that the Charnley remains the gold-standard for longevity in hip arthroplasty. The newer and more costly implants not only need to reproduce these results but also match the cost effectiveness of this prosthesis.

Different wear rates have been reported for ceramic-on-ceramic (COC) and metal-on-metal (MOM) hip replacements tested in simulators with different loading conditions and lubricants. We postulate that differences in wear rates may be associated with changes in lubrication and friction in the joint. This study aimed to compare the friction of COC and MOM bearings under different lubrication regimes, simulated by varying swing-phase loads and lubricants.

Alumina COC and CoCr MOM 28mm-diameter bearings were studied in a pendulum friction simulator. Flexion-extension of +/−25 degrees was applied to the head, a peak load of 2kN and swing-phase loads of 25N,100N, 300N used. Lubricants used included water, 25% and 100%-bovine serum.

COC and MOM bearings showed increased friction as the swing-phase load increased. COC bearings produced higher friction in 100%-serum compared to 25%-serum. In contrast, friction was lower when MOM bearings were tested in 100%-serum compared to 25%-serum. When COC bearings were tested in water, the friction decreased in comparison to testing in serum, however, MOM friction was higher in water.

Increasing the swing-phase load reduced the thickness of the fluid-film in the stance-phase and this increased friction. The increase in friction when COC bearings were tested in 100%-serum (compared to 25%) may be due to the increased forces required to shear the increased concentration of proteins, similarly friction is reduced in water. MOM bearing friction was reduced in 100%-serum, in this instance increased proteins may be acting as solid-phase lubricants, and similarly MOM friction increased in water.

Introduction: In vivo fluoroscopic studies have shown considerable differences in kinematics between different designs of knee prostheses and compared to the natural knee. Most noticeably, lift off of the femoral condyles from the tibial insert has been observed in many patients (Dennis et al, 2003). The aim of this study was to simulate lateral femoral condylar lift off in vitro and to compare the wear of fixed bearing knee prostheses with and without lift off.

Materials and Methods: 12 PFC Sigma cruciate retaining fixed bearing knees (DePuy, Leeds, UK) were tested. The 10 mm thick inserts were manufactured from GUR1020 UHMWPE and gamma irradiated in a vacuum. The inserts snap fitted into titanium alloy tibial trays, and articulated against Co-Cr-Mo alloy femoral components. The testing was carried out on six station simulators (Prosim, Manchester, UK). Femoral axis loading (maximum 2.6 kN) and the flex-ion-extension profile (0–58°) were adopted from ISO 14243 (1999). The internal/external rotation was ± 5° and anterior/ posterior displacement 0–5 mm. Six of the knees were tested under these standard conditions for 4 million cycles. A further six knees were tested under these conditions with the addition of lateral femoral condylar lift off, for 5 million cycles. The lift off was achieved by introducing an adduction moment to the tibial carriage, producing a separation of approximately 1 mm during the swing phase of the simulator cycle. The simulator was run at 1 Hz and the lubricant used was 25% newborn calf serum. Wear was determined gravimetrically, using unloaded soak controls to adjust for moisture uptake. Statistical analysis was performed using Students t-test (p < 0.05).

Results: Under the standard kinematic conditions the mean wear rate with 95% confidence limits was 8.8 ± 4.8 mm3/million cycles. When femoral condylar lift off was simulated the mean wear rate increased to 16.2 ± 2.9 mm3/million cycles, which was statistically significantly higher (p < 0.01). The wear patterns on the femoral articulating surface of all the inserts showed more burnishing wear on the medial condyle than the lateral. However, in the simulation of lift off the medial condyle was even more aggressively worn with evidence of adhesion and surface defects.

Discussion: The presence of lateral femoral condylar lift off resulted in a higher wear rate on the medial compartment of the PFC Sigma fixed bearing knee. This could be due to elevated contact stresses as the lateral lift off produced uneven loading of the bearing. Further, additional medial/lateral sliding of the medial condyle whilst it remained in contact may have accelerated the wear by cross shearing of the polyethylene in the medial/lateral direction. This direction is weakened when the polyethylene is preferentially molecularly orientated by sliding in the flexion-extension axis. The implications of condylar lift off include premature wear of the polyethylene and possible component loosening.

All polyethylene tibial components (APT) for total knee joint replacement have been recently reintroduced due to their past success and cost savings with respect to knee designs with a metal backed tibial tray (MBT). However, isolated cases of collapse of the medial bone in APT designs have been observed by the authors prompting this investigation. The objective of this study was to investigate the stress/strain distribution within the cancellous bone for the APT and MBT systems, particularly looking at the effects of coverage of the tray over the proximal tibia in each design. A three-dimensional finite element model of the proximal tibia implanted with a tibia tray was generated. An elliptical cylindrical tibia tray with a peg was modeled as being perfectly bonded to a PMMA layer on the superior surface of the cancellous and cortical bone. Gap size between the edge of the tray and outer of the cancellous bone, was introduced in the medial direction. Load was applied on the superior surface of the tibial insert in the medial side. Two lift-off loading cases were used, a low load of 800N (1 body-weight) and a high load of 3200N (4 x BW), both on the medial side. Permanent plastic deformation and collapse was allowed only in the cancellous bone, while all other materials were modeled elastically. Under low load conditions within the elastic limit, introducing a gap between the tray and the cortical bone produced a stress/strain intensity in the cancellous bone beneath the edge of the tray. The strain in the cancellous bone within the APT design was generally 3 times greater than the MBT design, however, peak strain values were similar at the edge of the tray. Whilst the strain increased with the introduction of a gap the resulting strain was not sensitive to the gap size for both designs. Under high load conditions, permanent plastic deformation and bone collapse were observed in the cancellous bone at the edge of the tibial tray in both designs where a gap was introduced. The maximum strain in the cancellous bone was found to be more sensitive to the gap size for the APT design than the MBT design. This can be contributed to the difference in the load transfer through the cancellous bone in the two designs. The MBT design with the more rigid tibial tray transfered higher load through the outer cortical bone than the APT design. The less rigid APT design resulted in progressive collapse of the cancellous bone beneath the tray. Particularly significant was the volume of highly stressed cancellous bone which was 4 times greater in the APT design compared to the MBT design. The results suggest that coverage may be a more important parameter for the APT design than the MBT design. The APT design may, therefore, be more suited to patients with better bone quality.

Introduction: Reduction of ultra high molecular weight polyethylene (UHMWPE) surface wear in total knee replacement (TKR) bearings may delay the onset of osteolysis and subsequent loosening of components. The aim of this study was to compare the effect of bearing material on UHMWPE wear using a physiological knee simulator.

Methods: LCS Rotating Platform (RP) mobile bearing TKRs (DePuy) were investigated with standard and custom insert materials (Table 1). Testing was completed on a six-station force/displacement controlled knee simulator (frequency 1 Hz). Kinematic inputs consisted of 0 – 58° extension-flexion [1], maximum 2600 N axial force [1], -262 to 110 N anterior-posterior force [1] and ± 5° internal-external rotation [2]. The test lubricant was 25% (v/v) bovine serum with 0.1% (m/v) sodium azide solution in sterile water. Six components of each material were tested for up to five million cycles. The mean wear rates of the inserts were determined gravimetrically after every million cycles.

Results and Discussion: The higher molecular weight 1050 GP exhibited a higher wear rate than 1020 NI but the difference was not statistically significant (p > 0.05) (Fig. 1). The medium level of crosslinking in the Marathon GP inserts significantly reduced wear in comparison to the uncrosslinked 1050 GP material (p < 0.05) and moderate crosslinking in the 1020 GVF also decreased wear compared with the 1020 NI base material although this was not statistically significant. However, these differences would not be considered to be clinically significant. In addition, further work should be completed to assess the biological activity of the crosslinked materials as increased biological response may negate the benefit of decreased volumetric wear. All RP materials exhibited significantly reduced wear rates (p < 0.05) in comparison to fixed bearing TKR tested under equivalent high kinematic conditions [3]. The RP translates complex motions into more unidirectional motions, benefiting from reduced wear due to decreased cross-shear on the UHMWPE compared with more multidirectional fixed bearing TKR. Therefore, TKR design is an important factor for reduction of UHMWPE wear.

Introduction: Following hip replacement surgery the tension of the soft tissues and the laxity of the joint may vary. Variations in surgical approach, technique and fixation method may influence the effective joint laxity and the level of force applied across the prostheses during the swing phase of gait. The aim of this study was to investigate the effect of different swing phase load conditions on the wear metal-on-metal hip prostheses using a hip simulator.

Methods: Cobalt chrome metal-on-metal bearings, 28mm in diameter were tested for five million cycles in a Prosim hip simulator with flexion-extension and internal-external rotation kinematic inputs. A Paul-type twin peak loading curve was applied, which was modified to provide three different swing phase load conditions;

Low positive swing phase load (< 100N)

All tests were carried out in 25% (v/v) new-born bovine serum, with gravimetric wear measurements completed every million cycles.

Results: The wear rates for the different swing phase conditions are shown in Figure I. Elevating the swing phase load from 100N to 300N (ISO load) increased the overall wear rate by 10-fold. Introducing microseparation into the gait cycle increased wear by a further 3-fold. These results indicate the sensitivity of metal-on-metal bearing wear to swing phase load conditions and joint laxity.

Discussion: Little attention to date has been paid to the importance of joint laxity and swing phase load on the wear rate of hip replacements. Elevation of wear rates with increased swing phase load was probably due to the depletion of fluid film lubrication. This was consistent with the findings under stop-start motion [Medley et al., 2002] and demonstrates the dependency of metal-on-metal hip replacements on fluid film lubrication conditions. Testing with a negative swing phase load elevated wear due to microseparation of the components, the head contacted the insert rim at heel strike which caused a stress concentration and damage to the insert rim. The results demonstrate that the wear performance of metal-on-metal hip replacements is highly dependent on swing phase load conditions. It is postulated that the fixation method and surgical technique can effect the swing phase load; over tensioning of the soft tissue may increase the swing phase load, whereas joint laxity will cause a negative swing phase load and possibly microseparation.

Aims: To review the effectiveness of the Posterior Lip Augmentation Device (P.L.A.D.) in treating recurrent prosthetic total hip dislocation. Method: We reviewed 36 patients from 2 hip revision surgeons from 2 UK centres who underwent cup augmentation using this device since October 1995. Data were collected from case notes, X-rays and clinical review. All dislocations were posterior (minimum of 3 dislocations). In the majority of cases the abductors were poor or detached, and 35 of the 36 patients had undergone at least one major operation on their hip before a P.L.A.D. was þtted (mean 2.2 operations). Results: The mean age at the time of P.L.A.D. was 73 years (range 47–94). The longest P.L.A.D. follow up is 72 months, and is working well without problems reported by the patient or visible changes on x-ray. A total of 26 out of 36 patients (72.2%) have had a successful correction of their dislocation over this mean period of 21 months (range 8 days Ð 72 months). 10 patients (27.8%) developed signiþcant problems of which 7 (19.4%) required removal of the implant. There were 4 unrelated deaths in our cohort. Conclusions: We feel it has a place in the treatment of recurrent dislocation, particularly in the frail patient, with well-þxed and orientated components, where risks of revision surgery are high and there will be less loading postoperatively