Aims

With up to 40% of patients having patellofemoral joint osteoarthritis (PFJ OA), the two arthroplasty options are to replace solely the patellofemoral joint via patellofemoral arthroplasty (PFA), or the entire knee via total knee arthroplasty (TKA). The aim of this study was to assess postoperative success of second-generation PFAs compared to TKAs for patients treated for PFJ OA using patient-reported outcome measures (PROMs) and domains deemed important by patients following a patient and public involvement meeting.

Introduction

Periprosthetic joint infection (PJI) can be difficult to diagnose. A variety of techniques have been described. The efficacy of the alpha-defensin laboratory test was examined and compared with other established modalities in the diagnostic workup of ‘real world’ arthroplasty patients.

Aim

Bacterial biofilms play a key role in prosthetic infection (PI) pathogenesis. Establishment of the biofilm phenotype confers the bacteria with significant tolerance to systemic antibiotics and the host immune system meaning thorough debridement and prosthesis removal often remain the only possible course of treatment. Protection of the prosthesis and dead-space management may be achieved through the use of antibiotic loaded cements and beads to release high concentrations of antibiotics at the surgical site. The antibacterial and antibiofilm efficacy of these materials is poorly understood in the context of mixed species models, such as are often encountered clinically.

Aim

To evaluate the ability of different combinations of antibiotic loaded cement to inhibit bacteria growth and biofilm formation.

Cement-in-cement femoral component revision is a useful and commonly practised technique. Onerous and hazardous re-shaping of the original cement mantle is required if the new stem does not seat easily. Furthermore, without removing the entirety of the original cement mantle, the freedom to alter anteversion or leg length is difficult to predict preoperatively. We present data from in vitro experiments testing the compatibility of the top cemented stems according to UK registry figures (NJR 2013). This data augments preoperative planning by indicating which revision stems require minimal or no cement reshaping when being inserted into another stem's mantle. We also present the maximum shortening and anteversion that can be achieved without reshaping the original cement mantle.

Summary Statement

Conventional culture techniques have poor sensitivity for detecting bacteria growing in biofilms, which can result in under-diagnosis of infections. Sonication of biofilm colonised orthopaedic biomaterials can render bacteria in biofilm more culturable, thereby improving diagnosis of orthopaedic implant infections.

Prosthetic joint infection(PJI) still remains a concern in orthopaedic practice. Antibiotic-loaded acrylic-cement(ALAC) is a proven means of lowering the incidence of PJI. However, increasing antimicrobial resistance has complicated both prophylaxis and treatment, prompting the use of combination antimicrobial therapy, with the addition of vancomycin to gentamicin-containing ALAC commonly used. The new antimicrobial, daptomycin, has better activity than vancomycin and we studied its elution from ALAC in comparison with vancomycin, along with its impact on the co-elution of gentamicin.

Cement beads were prepared from PalacosRG containing, 1g/2g daptomycin, 1g/2g vancomycin and without additional antibiotics. Six replicates of each combination were eluted in PBS at 37oC, at timed intervals, for up to 90days, the antibiotic loss was assessed using validated assays.

The mean recovery of gentamicin after 90days was 1.1mg with half eluted within the first 6 hours. Recovery was significantly increased by 60% and 40% with addition of 1g&2g of daptomycin(two-tail t-test: p=0.004 and p=0.02), respectively. Although there was a slight increase in gentamicin recovery in vancomycin loaded samples, this was not statistically significant(p>0.05).

The significant increases in gentamicin elution from Palacos RG when supplemented with daptomycin, along with a superior activity, may provide a better synergistic effect than PalacosRG supplemented with vancomycin in the management of PJI.

Introduction

In patients with adolescent idiopathic scoliosis (AIS), anomalous extra-spinal left-right skeletal length asymmetries in upper limbs, periapical ribs, and ilia beg the question as to whether these bilateral asymmetries are connected in some way with pathogenesis. The upper arm and iliac length asymmetries correlate significantly with adjacent spinal curve severity respectively in thoracic and lower (thoracolumbar and lumbar) spine. In lower limbs, skeletal length asymmetries and proximo-distal disproportion are unrelated to spinal curve severity. Overall, these observations raise questions about mechanisms that determine skeletal bilateral symmetry of vertebrates in health and disorder, and whether such mechanisms are involved in the cause of this disease. We investigated upper arm length (UAL) asymmetries in two groups of right-handed girls aged 11–18 years, with right thoracic adolescent idiopathic scoliosis (RT-AIS, n=98) from preoperative and screening referrals (mean Cobb angle 45°) and healthy controls (n=240).

Unstable fractures of the distal tibia are being increasingly treated by open reduction and internal fixation using pre-contoured locking plates. Functional outcome following this type of fixation has not been reported previously.

The aim of this study was to functionally assess patients following MIPO fixation of distal tibial fractures.

Case notes of 26 patients treated at a single centre were reviewed. The fracture type, fixation technique, complications, time to union and subsequent treatment were documented. All patients returned for functional scoring using the validated American Academy of Orthopedic Surgeons (AAOS) foot and ankle core score.

Twenty-six consecutive patients were treated between 2002-2005. The majority were male, and 5 were open fractures. There were 13 AO type A, 4 type B and 9 type C fractures. Mean follow up was 20 months. Average time from injury to surgery was 2.5 days. All fractures were treated by a MIPO technique. A pre-contoured distal locking plate was used for the distal tibial reconstruction. Secondary surgical procedures e.g. 2nd look, delayed primary closure, or skin grafting were necessary in 3 cases. The fibula was plated in 60% of cases. Four patients developed wound infections requiring antibiotics, and all resolved. The commonest rehabilitation regime was 6 weeks non weight bearing in plaster. Mean time to union was 18 weeks. There were 3 cases of delayed union, requiring bone grafting. One patient required removal of the plate due to local irritation, and one required a broken screw to be removed. Mean range of movement was 10 degrees dorsiflexion, 30 plantarflexion. The mean normalised AAOS foot and ankle core score was 41 (SD +/− 8).

We conclude that MIPO fixation of distal tibial fractures is a safe and effective method of treatment. Functional outcome does not significantly differ from that of the general population.

Background

High velocity vertical aircraft ejection seat systems are credited with aircrew survival of 80-95% in modern times. Use of these systems is associated with exposure of the aircrew to vertical acceleration forces in the order of 15-25G. The rate of application of these forces may be up to 250G per sceond. Up to 85% of crew ejecting suffer skeletal injury and vertebral fracture is relatively common (20-30%) when diagnosed by plain radiograph. The incidence of subtle spinal injury may not be as apparent.

We report a prospective case-series study to evaluate the results of non-operative and operative treatment of symptomatic unilateral lumbar spondylolysis. Non-operative treatment results in healing in most patients with symptomatic unilateral spondylolysis. Surgery however is indicated when symptoms persist beyond a reasonable time affecting the quality of life in young patients particularly the athletic population.

We treated 41 patients [31 male, 10 female] with suspected unilateral lumbar spondylolysis. Thirty-one patients were actively involved in sports at various levels. Patients with a positive stress reaction on SPECT imaging underwent a strict protocol of activity restriction, bracing and physical therapy for 6 months. At the end of six months, patients who remained symptomatic underwent a Computed Tomography [CT] scan to confirm the persistence of a spondylolysis. Seven patients subsequently underwent a direct repair of the defect using the modified Buck's Technique. Baseline Oswestry disability index [ODI] and Short-Form-36 [SF-36] scores were compared to two year ODI and SF-36 scores for all patients.

In the non-operated group, the mean pre-treatment ODI was 36 [SD=10.5], improving to 6.2 [SD=8.2] at two years. In SF-36 scores, the physical component of health [PCS] improved from 30.7 [SD=3.2] to 53.5 [SD =6.5] [p<0.001], and the mean score for the mental component of health [MCS] improved from 39 [SD=4.1] to56.5 [SD=3.9] [p<0.001] at two years. 20/31 patients resumed their sporting career within 6 months of onset of treatment, a further 4/31 patients returned to sports within one year.

The seven patients who remained symptomatic at six months underwent a unilateral modified Buck's Repair. The most common level of repair was L5 (n=4). The mean pre-operative ODI was 39.4 (SD=3.6) improving to 4.4 (SD=4) at the latest follow-up. The mean score of PCS [SF-36] improved from 29.6 [SD=4.4] to 51.2 [SD=5.2] (SD=5.2) (p<0.001) and the mean score of MCS (SF-36) improved from 38.7 (SD=1.9) to 55.5 (SD=5.4) (p<0.001).

A specific protocol of conservative treatment for patients with a unilateral lumbar spondylolysis resulted in a high rate of success with 83% of patients avoiding surgery. If symptoms persist beyond a reasonable period (i.e. 6 months) and reverse gantry CT scan confirms a non-healing defect of the pars interarticularis one may consider a unilateral direct repair of the defect with good outcome ultimately.

Our prospective observational study of patients treated for Thoracolumbar Adolescent Idiopathic Scoliosis (AIS) by anterior instrumentation aimed at investigating the correlation between the radiographic outcome and the recently-developed scoliosis research society self-reported outcomes instrument (SRS-22) which has been validated as a tool for self-assessment in scoliosis patients. Previous patient based questionnaires demonstrated poor correlation with the radiological parameters.

Manual templating using transparencies allows preoperative visualisation of anatomy and prosthesis size, as well as ease of exchange from prosthesis type to another. Most UK hospitals have converted X-ray provision to Picture Archiving and Communication Systems (PACS), necessitating the use of digital templating.

We assessed the accuracy and speed of templating for hip replacement on 36 occasions in 12 patients listed for hip replacement, using final component choice as an indicator of accuracy. Each hip was templated using, “Orthoview,” templating programme

without initial scaling and

A two pence coin taped to the lateral aspect of the thigh at the level of the greater trochanter was used for scaling purposes.

Our results showed acetate templating to be most accurate, correlating identically with the prosthesis stem size in 9/12 cases, and with the acetabulum reamed size on 10/12 occasions. Acetate templating was also the most accurate method when allowing for +/− one size difference, being within +/− one size in all 12/12 cases for both stem size and acetabulum size. In comparison, both scaled and non scaled Orthoview templating correlated with the correct femoral prosthesis size in 5/12 patients. The acetabulum ream size was correctly templated in 10/12 patients using unscaled Orthoview, and 8/12 patients using scaled Orthoview. Additionally, Orthoview templating took a mean of 6 minutes, whereas manual templating can be achieved in under 30 seconds.

Manual templating of scaled PACS images using transparencies conferred considerable advantages in terms of accuracy and speed. Moreover, this method allows a hands-on assessment of the forthcoming surgical procedure immediately prior to the operation, as well as late changes in implant choice. We recommend the continuation of manual templating using modern scaled digital images.

This report documents the clinical and histological findings, the operative management and the explant analyses of patients with early aseptic failure of large metal-on-metal (MonM) bearing joints.

Three hundred and fifty patients have been implanted with the ASR bearing surface (resurfacing or a modular THR) by a single surgeon at an independent centre since 2004. Six patients (all female) have been revised secondary to aseptic failure. All complained of severe groin pain exacerbated by straight leg raise and routine investigations were unable to establish a cause. Large amounts of sterile, highly viscous green fluid were aspirated from the hip joints in each case. Gross swelling of the pseudocapsule and a similar green fluid surrounding the implants were found at revision surgery. Histological examination of periprosthetic tissue samples showed changes consistent with ALVAL/metallosis, and analysis of the fluid revealed dense numbers of inflammatory cells. Symptoms in patients revised to ceramic-on-ceramic bearings improved post operatively. This was not the case with those reimplanted with MoM joints. Data from a subset of 76 patients (all unilateral resurfacings) showed that malaligned cups (anteverted > 20° +/− inclination angle > 45°) were associated with significantly higher whole blood metal ion levels than cups positioned within this range. All the patients with early aseptic failure had malaligned cups. Independent explant analysis revealed significant increases in the surface roughness values of the articular surfaces.

Our results suggest that some patients develop a significant inflammatory reaction to metal implants. This may be due to high levels of metal debris around the implant as a result of accelerated wear. Poor component alignment was found in all our patients with early aseptic failure.

Metal ion concentrations following metal on metal hip resurfacing arthroplasty remain a concern. Variables associated with increased metal ion concentrations need to be established. This study provides metal ion data from a consecutive cohort of the first 76 patients implanted with a fourth generation hip resurfacing prosthesis.

All patients agreed to post-operative blood metal ion sampling at a minimum of one year. Post-operative radiographic measurements of cup inclination and anteversion were obtained using the EBRA software. Mean whole blood chromium (Cr) and cobalt (Co) concentrations in patients receiving the smallest femoral implants (Ł51mm) were greater than in the patients implanted with the largest prostheses (ł53mm) by a factor of 3 and 9 respectively. Ion concentrations in the small femoral group were significantly related to acetabular inclination (R=0.439, P< 0.001 for Cr, R=0.372, P=0.004 for Co) and anteversion (R=0.330, P=0.010 for Cr, R=0.338, P=0.008 for Co). This relationship was not significant in the large implant group. Mean Cr and Co concentrations in patients with accurately orientated cups (inclination < 45°, anteversion < 20°) were 3.7μg/l and 1.8 μg/l respectively, compared to 9.1μg/l and 17.5μg/l in malaligned cups.

A reduced surface contact area caused by cup malalignment may increase contact stresses, resulting in a high wear rate if fluid film lubrication is inadequate. Improved fluid film lubrication has previously been found in larger heads in vitro. Accurate acetabular component positioning is essential in order to reduce metal ion concentrations following hip resurfacing.

Introduction: Classification systems are useful in research and clinical practise as it provides a common mode of communication and evaluation. Tibial pilon injuries are a complex group of fractures, whose classification and radiological assessment in clinical practise remains undetermined.

Methods: 50 CT scans and radiographs of tibial pilon fractures were evaluated independently by 6 orthopaedic surgeons, comprising 3 consultants, 2 registrars and 1 research fellow. Fractures were classified according to ruedi allgower, AO, Topliss et al. Each surgeon was given a period of 48 hours to review copy of the original article as well as written and diagrammatic representations. Assessment was done on two occasions, 4 weeks apart. The kappa coefficient of agreement was calculated with SPSS to determine interobserver reliability and intraobserver reproducibility of the classification systems. The evaluator was blinded as to treatment and functional outcome. Each evaluator was also asked to decide upon the fracture management based on the classification types and was compared with the actual management.

Result: The interobserver agreement for ruedi allgower, Ao and Topliss et al., was fair, moderate and poor respectively. The intraobserver agreement for ruedi allgower, AO and Topliss et al., classifications was moderate at best. There was poor agreement amongst observers regarding definite management plan based on these classification systems.

Discussion: The interobserver agreement was directly proportional to the familiarity and inversely proportional to the specificity of the classification system. The intraobserver agreement improved with experience. CT scan helped in delineating the fracture segments accurately but did not significantly affect inter or intraob-server agreement.

Conclusion: Existing classification systems help in understanding the pathoanatomy of osseous part of tibial pilon fracture complex. However, Soft tissue injury forms an integral part of this complex. Without inclusion of soft tissue injury, these classification systems have limited role in definitive management.

Introduction: The use of an ejection seat to escape from a stricken aircraft is associated with the exposure of significant forces. These vertical accelerative forces on the body are in the order of 15–25G with rates of onset of up to 250G per second. Therefore, it is common to see vertical compression fractures, mainly in the thoracolumbar region. Although most vertebral fractures are evident on plain radiographs, subtle spinal injuries elsewhere may not be immediately apparent.

Aim: A prospective study to evaluate for the presence of occult spinal injuries using MRI following aircraft ejection.

Methods: Between 1996 and 2003, 22 ejectees from 18 aircrafts, mean age 32 years (range 24 to 48), were admitted to a regional spinal unit for comprehensive evaluation of their injuries that included whole spine radiographs and Magnetic Resonance Imaging (T1, T2 weighted and STIR sagittal sequences). All ejections occurred within the ejection envelope and were flying below 2000 ft (mean 460 feet) and below 500 knots airspeed (mean 275 knots).

Results: All 5 ejectees (23%) with vertebral compression fractures, one at T6 and 4 in thoracolumbar region, had pain and tenderness in the appropriate area of the spine that was evidently detected on plain radiographs. 3 of these patients with a thoracolumbar fracture (AO A3.3) had more than 50% canal compromise and more than 30 degrees angular kyphosis underwent surgery. Neurological compromise consisting of acute cauda equina syndrome occurred in one patient with a L2 AO A3.3 fracture. More importantly 10 ejectees (45%) had MRI evidence totalling 21 occult thoracic and lumbar vertebral fractures. 4 ejectees had a single occult fracture, 4 had double, 1 had 3 and 1 had 6 occult fractures.

Conclusion: This study confirms the high incidence of occult vertebral injuries following vertical acceleration insult to the spine consequent to emergency aircraft ejection. Once life-saving priority measures have taken place MRI of the entire spine remains mandatory as part the comprehensive evaluation of the patient. Early use of MRI scanning in the management will significantly increase an ejectee’s safe return to flying duties.

Purpose: There is no consensus regarding indications for anterior release and causative factors of junction kyphosis(JK) in Scheuermann’s Kyphosis(SK).

Methods: A retrospective review of 35 patients(19♂; 16♀) who underwent surgery for SK with a minimum follow-up of 5 years was undertaken. The mean age & follow-up were 20.5(13.25–45.75y) and 9 years(5–22y) respectively. Patient demographics, clinicoradiological parameters & functional outcomes (ODI/SRS-22) were assessed. The incidence of JK was correlated with radiographic parameters & instrumentation levels. Outcomes of posterior instrumentation(GroupI-13) were compared with anterior release & posterior instrumentation(GroupII-22).

Results: Cobb Λle of ≥600 hyperextension radiographs and presence of anterior bony bridge required anterior release. JK(≥100) was seen in 12 cases (7 proximal & 5 distal). PJK was seen in cases where T3-4 was the upper instrumented vertebra(UIV). DJK was seen in patients with body mass index(BMI) of ≥30 and when LIV did not include 1st lordotic disc. There was significant difference in mean thoracic kyphosis(TK) correction between the 2 groups (35.70vs44.50;p=0.003). The mean loss of correction at 9 yrs was 5.90 and 3.40 respectively. 33/35 were subjectively satisfied with cosmesis and 28/35 patients returned to their previous occupation. Three were off work due to chronic back pain and four patients had job modifications.

Conclusion: Stiff curves require anterior release. PJK could be overcome by including T2 as UIV.

DJK could be prevented by including 1st lordotic disc in LIV. Extending lower Instrumentation to L3 would reduce the risk of implant failure in obese patients. There was no advantage of cages over rib grafts.

Ethics approval: Not applicable

Interest Statement: None (No grants obtained from any agency)

Introduction: There are ongoing concerns regarding metal wear debris following the use of metal-on-metal (MonM) bearings for hip surface and total arthroplasty. A Type IV Hypersensitivity reaction to MonM articulations has previously been identified (aseptic lymphocyte dominated vasculitis associated lesion, ALVAL) but little is known of its incidence, diagnosis or management. Persisting groin pain in MonM patients may be undiagnosed ALVAL. At our single centre we have reviewed and compared three types of MonM articulations to examine the incidence of ALVAL and to identify trends.

Methods: The resurfacing group comprised 250 patients with the ASR prosthesis. In the resurfacing hybrid total hip replacement (THR) group there were 86 patients implanted with an ASR head on a stem. The final group comprised of 625 patients with a MonM THR using a 36mm Pinnacle head. Both the S-ROM and the Corail stems were used in the THR groups. Patients with persisting and activity-restricting groin pain had tests for infection. Patients were counselled and revision was offered if ALVAL was suspected from the clinical picture, blood results and the aspiration result. Specimens for microbiological and histological analysis were taken at the time of revision.

Results: We found 5 cases of histologically proven ALVAL in the absence of infection in 961 patients. The incidence was: 1.2% in the resurfacing group, 2.3% of Resurfacing Hybrid THR group and 0 in the 36 mm THR group. All 5 cases were in female patients. Only 1 case had any radiological abnormality. One patient was initially revised from a resurfacing to a 36mm MonM THR without clinical success. All patients have now been revised to ceramic-on-ceramic bearings with improvements in outcome.

Discussion: ALVAL may be under-diagnosed. The 5 patients we describe showed good clinical recovery following their primary procedure. However, activity levels decreased and pain increased at 6–12 months post-op. All described non-specific systemic symptoms. On examination, a painful straight leg raise was a characteristic finding. This may result from the significant effusion found around the hip at each revision. Fluid aspirated from these hips was of a characteristic colour (green grey) and viscosity. The failure of the revision of a resurfacing to a smaller MonM bearing highlights the problem of sensitisation to the metal debris. Any subsequent revision to a MonM bearing is unlikely to improve clinical outcome. This finding is consistent with previous reports in the literature. Our results suggest the incidence of ALVAL may be higher that previously thought. We suggest all patients with significant groin pain should have inflammatory markers tests and a hip aspiration performed. In the absence of infection, revision to an alternative bearing surface may be indicated.

Introduction: Potential problems resulting from metal-on-metal hip wear debris are well known. Previous studies have shown an association between high cup angles and raised metal ion levels, but a link to clinical outcome has yet to be established. We aim to show the relationship between high cup angles, raised metal ion levels and pain following hip resurfacing.

Methods: This analysis comprised the first 250 Depuy ASR hip resurfacings performed by a single surgeon (senior author) over a 3 yr period at an independent centre. Patients were followed up, examined and x-rayed at regular intervals. We measured Harris Hip Score (HHS) and pain. The acetabular cup inclination angles were measured from standardised pelvic radiographs. A subgroup of 80 patients had serum and whole blood chromium and cobalt measurements performed. This subgroup comprised patients with a similar sex split, age, activity level, follow-up and cup angle profile to the parent group.

Results: HHS improved from 51.6 pre-operatively to 94.6 post-operatively. Males had a significantly higher post-op HHS (97.1) compared with the females (91.0). 2.1% of male patients had pain compared with 8.7% of females. High cup angles were associated with pain in females. This relationship did not occur in males. In patients with cup angles of 48° and above there were no males with pain compared to 15.4% of females. Females under 48° had a HHS of 93.7 compared to 88.0 for those over 48°. When we analysed metal ion levels there was a similar relationship. Patients with cup angles of 48° and above had significantly higher serum and whole blood chromium and cobalt levels compared with lower cup angles. Three patients with cup angles over 50° developed ALVAL (aseptic lymphocyte dominated vasculitis associated lesion) based on histological findings. All were female.

Discussion: High cup angles are associated with increased pain and elevated metal ion levels. Women seem to be more intolerant of an higher cup angle than men. This may be a consequence of the smaller prostheses in females. Cups implanted lower than 48° had a better clinical outcome and less metal ion wear. Like other 4th generation designs, the ASR cup is not a complete hemisphere (unlike the BHR) and may be susceptible to edge loading at lower inclination angles than previously thought. We believe the current recommendation of 45° +/−5° is too high based on our findings. We recommend an inclination angle that does not exceed 48°.