High tibial osteotomy (HTO) is an effective surgical treatment for isolated medial compartment knee osteoarthritis; however, widespread adoption is limited due to difficulty in achieving the planned correction, and patient dissatisfaction due to soft tissue irritation. A new HTO system – Tailored Osteotomy Knee Alignment (TOKA®, 3D Metal Printing Ltd, Bath, UK) could potentially address these barriers having a custom titanium plate and titanium surgical guides featuring a unique mechanism for precise osteotomy opening as well as saw cutting and drilling guides. The aim of this study was to assess the accuracy of this novel HTO system using cadaveric specimens; a preclinical testing stage ahead of first-in-human surgery according to the ‘IDEAL-D’ framework for device innovation.

Local ethics committee approval was obtained. The novel opening wedge HTO procedure was performed on eight cadaver leg specimens. Whole lower limb CT scans pre- and post-operatively provided geometrical assessment quantifying the discrepancy between pre-planned and post-operative measurements for key variables: the gap opening angle and the patient specific surgical instrumentation positioning and rotation - assessed using the implanted plate.

The average discrepancy between the pre-operative plan and the post-operative osteotomy correction angle was: 0.0 ± 0.2°. The R2 value for the regression correlation was 0.95.

The average error in implant positioning was −0.4 ± 4.3 mm, −2.6 ± 3.4 mm and 3.1 ± 1.7° vertically, horizontally, and rotationally respectively.

This novel HTO surgery has greater accuracy and smaller variability in correction angle achieved compared to that reported for conventional or other patient specific methods with published data available. This system could potentially improve the accuracy and reliability of osteotomy correction angles achieved surgically.

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Patients with knee prosthetic joint infection (PJI) frequently receive one- or two-stage revision. To explore the feasibility of a randomised controlled trial (RCT) comparing methods, we analysed a UK registry, interviewed patients and surgeons, systematically reviewed literature, held a consensus meeting, and assessed progress of an RCT in hip PJI. In 2014, in England and Wales, knee PJI was treated with one- or two-stage procedures in 19% and 71% of patients respectively. Between 2007 and 2014, use of one-stage procedures doubled and, in major centres, up to 42% of treatments were one-stage. We conducted in-depth interviews with 16 patients with knee PJI and 11 surgeons performing one- or two-stage revision. Patients considered randomisation acceptable with appropriate counselling and, depending on infecting organisms and health status, surgeons would randomise treatments. In meta-analysis, two-year re-infection rates in 10 one-stage series (423 patients) and 108 two-stage series (5,129 patients) were 7.6% (95%CI 3.4,13.1) and 8.8% (7.2,10.6) respectively. In a series of patients with knee PJI, surgeons from 2 major centres considered 6/15 patients eligible for either treatment, with 4 more potentially eligible after treatment of soft tissue infection. In an ongoing RCT of surgical treatment of hip PJI, 116 patients have been randomised at 14 centres in 3 years. Randomising patients with PJI is feasible but, as knee PJI is uncommon, a multicentre RCT would be required. Based on WOMAC score outcome and appropriate assumptions on eligibility and acceptability, 170 patients would need to be randomised over 4 years at 14 major centres.

Prosthetic joint infection (PJI) is an uncommon but serious complication of hip and knee replacement. We investigated the rates of revision surgery for the treatment of PJI following primary and revision hip and knee replacement, explored time trends, and estimated the overall surgical burden created by PJI.

We analysed the National Joint Registry for England and Wales for revision hip and knee replacements performed for a diagnosis of PJI and their index procedures from 2003–2014. The index hip replacements consisted of 623,253 primary and 63,222 aseptic revision hip replacements with 7,642 revisions subsequently performed for PJI; for knee replacements the figures were 679,010 primary and 33,920 aseptic revision knee replacements with 8,031 revisions subsequently performed for PJI. Cumulative incidence functions, prevalence rates and the burden of PJI in terms of total procedures performed as a result of PJI were calculated.

Revision rates for PJI equated to 43 out of every 10,000 primary hip replacements (2,705/623,253), i.e. 0.43%(95%CI 0.42–0.45), subsequently being revised due to PJI. Around 158 out of every 10,000 aseptic revision hip replacements performed were subsequently revised for PJI (997/63,222), i.e. 1.58%(1.48–1.67). For knees, the respective rates were 0.54%(0.52–0.56) for primary replacements, i.e. 54 out of every 10,000 primary replacements performed (3,659/679,010) and 2.11%(1.96–2.23) for aseptic revision replacements, i.e. 211 out of every 10,000 aseptic revision replacements performed (717/33,920). Between 2005 and 2013, the risk of revision for PJI in the 3 months following primary hip replacement rose by 2.29 fold (1.28–4.08) and after aseptic revision by 3.00 fold (1.06–8.51); for knees, it rose by 2.46 fold (1.15–5.25) after primary replacement and 7.47 fold (1.00–56.12) after aseptic revision. The rates of revision for PJI performed at any time beyond 3 months from the index surgery remained stable or decreased over time.

From a patient perspective, after accounting for the competing risk of revision for an aseptic indication and death, the 10-year cumulative incidence of revision hip replacement for PJI was 0.62%(95%CI 0.59–0.65) following primary and 2.25%(2.08–2.43) following aseptic revision; for knees, the figures were 0.75%(0.72–0.78) following primary replacement and 3.13%(2.81–3.49) following aseptic revision.

At a health service level, the absolute number of procedures performed as a consequence of hip PJI increased from 387 in 2005 to 1,013 in 2014, i.e. a relative increase of 2.6 fold. While 70% of those revisions were two-stage, the use of single stage revision increased from 17.6% in 2005 to 38.5% in 2014. For knees, the burden of PJI increased by 2.8 fold between 2005 and 2014. Overall, 74% of revisions were two-stage with an increase in use of single stage from 10.0% in 2005 to 29.0% in 2014.

Although the risk of revision due to PJI following hip or knee replacement is low, it is rising. Given the burden and costs associated with performing revision joint replacement for prosthetic joint infection and the predicted increased incidence of both primary and revision hip replacement, this has substantial implications for service delivery.

Opening wedge high tibial osteotomy (OWHTO) is a treatment option for medial compartment osteoarthritis of the knee in the young active adult. Limited evidence exists in the literature regarding return to activities following OWHTO.

We performed a retrospective study of local patients who underwent OWHTO from 2005 – 2012 assessing post-operative return to sporting function. Patients with additional knee pathology, surgery or alternative issues affecting activity were excluded.

110 patients met inclusion criteria, 75 were successfully contacted.

Mean improvement in pain score = 4.8/10 (95%CI 4.2 to 5.4, p<0.01). Mean pre-operative KOS-SAS score = 0.5/2, mean post-operative KOS-SAS score = 1.1/2, mean change in KOS-SAS score following OWHTO = 0.6 (95% CI 0.5 to 0.7, p<0.01). Mean pre-morbid Tegner score = 5.9/10, pre-operative = 2.7/10, post-operative = 4.2/10. Mean change in Tegner score following OWHTO = 1.5 (95% CI 1 to 1.9, p<0.01). Following OWHTO 25% of patients achieved pre-morbid Tegner scores. Patient BMI, age, type of implant or graft used had no significant effect on outcome.

OWHTO can temporarily improve pain, activity and sporting levels in young patients with isolated medial compartment knee OA. Return to pre-morbid activity levels and even high level sports function is possible although not the norm.

Limited literature exists providing comprehensive assessment of complications following opening wedge high tibial osteotomy (OWHTO). We performed a retrospective study of local patients who underwent OWHTO for isolated medial compartment knee osteoarthritis from 1997–2013.

One hundred and fifteen patients met inclusion criteria. Mean follow-up = 8.4years. Mean age = 47 (range 32–62). Mean BMI = 29.1 (range 20.3–40.2). Implants used included Tomofix (72%), Puddu plate (21%) and Orthofix (7%) (no significant differences in age/ sex/ BMI). Wedge defects were filled with autologous graft (30%), Chronos (35%) or left empty (35%).

Five year survival rate (conversion to arthroplasty) = 80%. Overall complication rate = 31%. 25% of patients suffered 36 complications including minor wound infections (9.6%), major wound infections (3.5%), metalwork irritation necessitating plate removal (7%), non-union requiring revision (4.3%), vascular injury (1.7%), compartment syndrome (0.9%), and other minor complications (4%). No thromboembolic complications were observed.

A higher BMI (mean 34.2) was apparent in those patients suffering complications than those not (mean 26.9). No significant differences existed in complication rates relative to implant type, type of bone graft used or patient age at surgery.

Complications following OWHTO appear higher than previously reported in the literature; serious complications appear rare.

Kinematic alignment has increased in popularity over the last few years in an attempt to improve clinical outcomes following total knee arthroplasty (TKA).

In our unit kinematic alignment has been used with patient-specific cutting guides as part of on-going clinical trials. We performed a retrospective analysis on all the TKA which had been planned to be implanted outside of the mechanical axis (0° ± 3°) based on pre-operative MRI scans and looked at their radiographic and clinical outcomes.

We identified 21 knees which had been implanted as ‘planned outliers’. All had clinical and radiographic follow up to a mean 11.6 months post op. All had a standard long leg alignment radiograph performed at 6 weeks post op to confirm alignment.

All patients had a good improvement in their Oxford Knee Scores with mean improvement from 23 pre-op to 42 at 1 year. Of our patients none had a poor clinical outcome due to the alignment of their TKA, 1 patient had a poor outcome because of a quadriceps rupture which occurred 4 months post-op. There were no post-operative radiographic abnormalities.

In our unit kinematic alignment outside of the mechanical axis is not associated with an increased rate of short term complications.

We aimed to analyse complication rates following medial opening-wedge high tibial osteotomy (OWHTO) for knee OA.

A regional retrospective cohort study of all patients who underwent HTO for isolated medial compartment knee OA from 2003–2013.

115 OWHTO were performed. Mean age = 47 (95%CI 46–48). Mean BMI = 29.1 (95%CI 28.1–30.1).

Implants used: 72% (n=83) Tomofix, 21% (n=24) Puddu plate, 7% (n=8) Orthofix Grafts used: 30% (n=35) autologous, 35% (n=40) artificial and 35% (n=40) no graft. 25% (n=29) of patients suffered 36 complications. Complications included minor wound infection 9.6%, major wound infection 3.5%, metalwork irritation necessitating plate removal 7%, non-union requiring revision 4.3%, vascular injury 1.7%, compartment syndrome 0.9%, and other minor complications 4%.

Apparent higher rates of non-union occurred with the Puddu plate (8.3%) relative to Tomofix (3.6%) but was not statistically significant. No other significant differences existed in complication rates relative to implant type, bone graft used, patient age or BMI.

Serious complications following HTO appear rare. The Tomofix has an apparent lower rate of non-union compared to older implants but greater numbers are required to determine significance. There is no significant difference in union rate relative to whether autologous graft, artificial graft or no graft is used.

We sought to validate a method of measuring the range of motion of knees on radiographs as part of a new system of “Virtual Knee Clinics”.

The range of motion of 52 knees in 45 patients were first obtained clinically with goniometers and compared to radiographs of these patients' knees in full active flexion and extension. Four methods of plotting the range of motion on the radiographs were compared.

The intra-class correlation coefficient (ICC) for inter-rater reliability using the goniometer was very high; ICC=0.90 in extension and 0.85 in flexion. The best ICC for radiographic measurement in extension was 0.86 indicating substantial agreement and best ICC in flexion was 0.95 (method 4). ICC for intra-rater reliability was 0.98 for extension and 0.99 for flexion on radiographic measurements.

Measuring range of motion of the knee has never previously been validated in the literature. This study has allowed us to set up a “Virtual Knee Clinic,” combining postal questionnaires and radiographic measurements as a surrogate for knee function. We aim to maintain high quality patient surveillance following knee arthroplasty, reduce our new to follow-up ratios in line with Department of Health guidelines and improve patient satisfaction through reduced travel to hospital outpatients.

We report the largest multicentre series analysing the use of bone scans investigating painful post-operative Total Knee Replacements (TKR). We questioned the usefulness of reported scintigraphic abnormalities, and how often this changed subsequent management. 127 three-phase bone-scans were performed during a two-year period. Early and late flow phases were objectively classified. Reported incidences of infection and loosening were determined. Reports were subjectively summarised and objectively analysed to establish the usefulness of this investigation. Eight cases were excluded.

Scans were classified as: 33% (39) normal, 53% (63) as possibly abnormal, 6% (7) probably abnormal, and 8% (10) as definitely abnormal. Thirteen patients (11%) underwent revision TKR surgery. Intra-operative analysis revealed loosening of one femoral component, and massive metallosis of the patella in another. Cultures were negative in all cases. The sensitivity and specificity of a definitely abnormal investigation in predicting need for revision surgery was 23% and 82% (respectively). High instances of ambiguously reported abnormalities were observed.

This investigation has no role to play in the routine investigation of a painful TKR. It is unnecessary in investigation of periprosthetic infection and should not be used in a routine assessment of a painful TKR. If used it should be limited until an experienced revision surgeon has made a full assessment.

Background

Patellar instability is a complex, multi-factorial disorder. Radiological assessment is regarded as an important part of the management of this population. The purpose of this study was to determine the intra- and inter-rater reliability of common radiological measurements used to evaluate patellar instability.

Purpose

Great expense is accumulated in investigation and management, often with poor outcome, of a patient with a painful TKR. We aim to produce guidelines for their investigation and careful, successful management.

ARMD (Adverse Reaction to Metal Debris) is an increasingly recognised complication of metal on metal hip replacements. The MHRA (Medical and Healthcare Related Devices Agency) have advised a blood cobalt or chromium level above 7 mg/L is a threshold for further investigation, stating that “low levels are reassuring and strongly predict not having an adverse outcome”. Cross-sectional imaging should be performed when levels are above 7 mg/L. We have performed a study investigating the specificity and sensitivity of chromium and cobalt metal ion levels as a screening measure for ARMD.

79 ASR hip replacements were performed at our hospital and 75 (95%) of these underwent a Metal Artefact Reduction Sequence (MARS) MRI scan. All patients (64 hips) who had not undergone revision were invited to take part in this study. 57 patients with 62 hip replacements completed hip and activity scores, had blood cobalt and chromium ion level measurements and 3D-CT to measure acetabular component position.

Acetabular component inclination (>50 degrees), small head size (< 51mm) and female gender were significantly correlated with raised chromium (Cr) and cobalt (Co) ion levels. An ARMD was detected using MRI in 18 (29%) of the hips in this study. The incidence of ARMD was significantly higher when chromium concentration was above 7 mg/l (p = 0.02). Chromium ion levels >7 mg/L had a sensitivity of 56% and specificity of 83% for ARMD, and cobalt ion levels >7 mg/L 56% and 76% respectively. 40 patients had cobalt levels <7 mg/L and 33 had chromium levels <7 mg/L, but 8 of these had an ARMD on MRI. All 8 patients had minimal symptoms (Oxford Hip Score ≥ 44 out of 48).

The Medicines and Healthcare Products Regulatory Agency (MHRA) has recommended that cobalt and chromium levels be measured in patients with a metal-on-metal hip replacement and cross-sectional imaging performed when these levels are above 7 μg/L. This study has shown that by using this threshold, in patients with this implant combination, the sensitivity and specificity for the detection of ARMD is low and patients with soft tissue disease may be missed. Furthermore the presence of MRI detected ARMD, in the absence of significant clinical symptoms and with metal ion levels <7 μg/L is of concern.

MoM implants at risk of failure are associated with raised cobalt and chromium levels. However metal ion analysis alone is not reliable as a screening tool for ARMD, which is often clinically “silent”. We recommend the routine use of MARS MRI as the safest method of ARMD diagnosis in patients with MoM implants.

Allogeneic blood transfusion is associated with many complications and significant cost. The RD&E has looked at the use of autologous drains after our study of 100 cases showed an improved post-operative haemoglobin and reduced length of stay. There is a need to identify those patients of increased need for an autologous drain, in order to decrease the frequency of allogeneic transfusion. In 2007 a protocol was drawn up using information from our study of 191 cases which showed an average haemoglobin drop post-operatively of 3.05g/dl and average intra-operative blood loss of 285 ml. This protocol gives the surgeon triggers for autologous drain use; preoperative haemoglobin of <13g/dl, intra-operative blood loss of >400ml, tourniquet use, patient weight <50kg and patients refusing donated blood.

In 2007-08, 65% of a further 275 cases analysed met the triggers for use of an autologous system. The remaining patients received low vacuum drains. Of the 275 patients, only 2 (<1%) of those who did not fulfil the criteria for an autologous drain required allogeneic blood, compared with 43 patients (24%) of those deemed high risk of transfusion, and assigned autologous drains. The protocol was therefore deemed to be successful in identifying those patients who required additional support and expenditure to minimise allogeneic blood transfusion.

Analysis of this data led to recommended changes to the protocol in order to maximise the efficiency of the autologous drain use. In 2010 a further patient cohort studied showed a reduction in allogeneic blood transfusion to <10% of those receiving autologous drains, and an increase to 5% of those with low vacuum drains.

Due to the increased cost of autologous drains (£68) compared with the low vacuum systems (£32), and the cost of allogeneic units at £141, the expenditure per patient was calculated and shown to fall from £92 in 2007 to £78 in the 2010.

In conclusion, this protocol allows the clinician to appropriately target the use of the more expensive autologous drains to those of increased risk of transfusion. This protocol helps to minimise unnecessary allogeneic blood transfusion risks, and this has been shown to be more cost effective.

Weight-bearing is a known stimulus for bone remodelling and a reduction in weight-bearing is associated with reduced bone mineral density (BMD) in affected limbs post lower limb fracture. This study investigated short and long-term precision of a method for measuring relative left/right weight-bearing using two sets of identical calibrated scales. The effect of imbalance on BMD at the hip and on lower limb lean tissue mass (LLTM) was also assessed.

46 postmenopausal women, with no history of leg or ankle fracture, were measured three times whilst standing astride two scales (Seca, Germany). 34 of the participants were re-measured after 6 months by the same method. Bilateral hip and total body dual x-ray absorptiometry measurements were performed using a GE Lunar Prodigy (Bedford, MA). Precision errors in weight-bearing measures were calculated using the root mean square coefficient of variation (RMSCV%). The correlations at the first visit between left/right differences in weight-bearing and differences in BMD and LLTM were calculated.

The short-term RMSCV% for left and right weights were 4.20% and 4.25% respectively and the long-term RMSCV% were 6.91% and 6.90%. Differences in left/right weight-bearing ranged from 0 to 24% (SD 8.63%) at visit 1 and 0 to 30% (SD 10.71%) at visit 2. Using data from visit 1, the relationship between hip BMD differences and left/right weight-bearing differences were investigated, with no significant correlations found. However, a weak, but statistically significant correlation of r=0.35 (p=0.02) was found for differences in LLTM and left/right weight-bearing differences.

In conclusion, left/right weight-bearing measured using two scales is a precise method for evaluating differences in weight-bearing in the short and long-term. Differences in left/right weight-bearing in this population varied by up to 30%. Participants showed a high degree of consistency in their long-term balance in a natural standing posture. Inequalities in left/right weight-bearing did not correlate significantly with BMD at the hip, but demonstrated a weak but statistically significant correlation with lean tissue mass.