Aims

Prosthetic joint infection (PJI) and aseptic loosening in total hip arthroplasty (THA) can present with pain and osteolysis. The Musculoskeletal Infection Society (MSIS) has provided criteria for the diagnosis of PJI. The aim of our study was to analyze the utility of F18-fluorodeoxyglucose (FDG) positron emission tomography (PET) CT scan in the preoperative diagnosis of septic loosening in THA, based on the current MSIS definition of prosthetic joint infection.

Background

Modularity in total hip replacement(THR) enables precise recreation of native hip biomechanics. However, there have been concerns about raised metal ion levels with increased number of interfaces. We present the 3 year results of ML taper with Kinectiv technology(MLKT), a modular neck uncemented stem. This system has modular neck options, but has only one [0] head in various diameters.

Introduction

Fluorodeoxuglucose(FDG) Positron Emission Tomography(PET) scan is used in the diagnosis of prosthetic joint infection, when the inflammatory markers and aspiration of the joint do not establish a definitive diagnosis. The aim of our study was to analyse the utility of FDG PET scan in decision making in these patients.

Introduction

It is standard practice to send samples for microbiological and histological analysis during revision surgery in suspected prosthetic joint infection. The aim of our study was to analyse the utility of histology in decision making in these patients.

There has been a significant decline in the use of metal-on-metal (MoM) bearings due to concerns regarding adverse reaction to metal debris (ARMD). The Medicines and Healthcare products Regulatory Agency (MHRA) recommends annual follow-up for life with blood Cobalt (Co) and Chromium (Cr) ion level measurement in all MoM THRs with femoral head size greater than or equal to 36mm. We present the serial ten year serum Co and Cr levels in a cohort of large head MoM THRs and analyse the utility of measuring serum ions levels annually.

All patients who underwent unilateral large head MoM THR between January 2004 and December 2006 were included in this prospective study. Annual serum Co and Cr measurements were measured. Clinical case notes and radiographs were reviewed for failure, revision surgery and the occurrence of ARMD. Mann Whitney test was used to analyse changes in serum Co and Cr levels. Receiver Operating Characteristic (ROC) curve was plotted based on their sensitivity and specificity to detect ARMD.

256 patients were included. There was a significant increase in serum ion values in the first two years. After 7 years, there was no significant change in Co values(p=0.78) and there was a decline in Cr value after 9 years(p<0.001). With 7 µg/l as the cut-off value, the sensitivity and specificity of Co was 82.1% and 65.5% and of Cr was 53.5% and 91.3%.

Annual follow-up of patients with MoM THR based on the MHRA guideline to obtain serum metal ion levels can cost about £9 million/year. Our study noted poor discriminatory ability for both Co and Cr values in the ROC curve. There is poor correlation between serum metal ion levels and the occurrence of ARMD on MARS MRI. Based on our results we find limited utility in doing ion levels after 7 years in asymptomatic patients.

High failure rates have been associated with large diameter metal-on-metal total hip replacements (MoM THR). However there is limited literature describing the outcomes following the revision of MoM THR for adverse local tissue reaction (ALTR).

A total of 98 large diameter MoM THRs underwent revision for ALTR at our institution. The data was obtained from the clinical records and included the demographics, intra-operative findings of ALTR and post-operative complications. Any subsequent procedures and re-revision for any reason was analysed in detail. The clinical outcome was measured using functional outcome scores using the Oxford hip score (OHS), Western Ontario and McMaster Universities osteo-arthritis index (WOMAC) score and Short Form (SF12).

The mean age of the patients at the time of revision was 58.2 yrs. At a mean follow-up of 3.9 years (1.0 to 8.6) from revision for ALTR, there were 15 hips (15.3 %) with post-operative complications and 8 hips (8 %) requiring re-revision. The Kaplan–Meier five-year survival rate for ALTR revision was 91 % (95% confidence interval 78.9 to 98.0). There were no statistically significant predictors of re-revision. The rate of postoperative dislocation following revision was 9.2% (9 hips). The post-operative functional outcome depends on the intra-operative findings of tissue destruction secondary to ALTR.

The short term results following revision of large diameter MoM THR for ALTR are comparable with other reports in the literature. The use of constrained liners reduces the incidence of post-operative dislocation. There is an increased risk of postoperative instability following revision THR for ALTR. Early identification and intervention seems to be the logical approach in the management of patients with ALTR.

The effectiveness of intravenous tranexamic acid (TA) in reducing blood loss and transfusion requirements during total hip replacement (THR) is well recognised. The aim of this study was to assess the effectiveness of a fibrin sealant in comparison to intravenous TA and a control group.

We prospectively studied 270 patients with primary hip osteo-arthritis who underwent a straight forward THR between February 2012 and September 2013. The first 70 patients acted as the control group. The next 100 consecutive patients received fibrin sealant spray before closure and the last 100 patients received 1g TA on induction. Demographic data, comorbidities, surgical time, surgeon grade, anaesthetic type, haemoglobin drop post-operative and transfusion requirements were analysed using one-way ANOVA.

The demographic characteristics, surgical time, surgeon grade, anaesthetic type and pre-operative haemoglobin of the 3 groups were comparable. Both fibrin sealant and intravenous TA were effective in reducing blood loss during THR (15%, p = 0.04 & 22.5%, p = 0.01, respectively), when compared to the control group. However, neither treatment was found to be superior to the other in preventing blood loss p = 0.39. Tranexamic acid was superior to fibrin sealant in decreasing allogeneic transfusion requirements (0% vs 10%, p = 0.05). The LOS was significantly shorter in the tranexamic acid group than fibrin sealant group and in the fibrin sealant group compared with control group. There was no significant difference between the groups with regards to proportion of patients with wound leaking problems. No other complications (e.g. VTE) were encountered

Both fibrin sealant and intravenous tranexamic acid were effective in reducing blood loss. However, tranexamic acid use reduced post-operative transfusion requirements.

Introduction:

Wear debris from articulating joint implants is inevitable. Small debris particles are phagocytosed by macrophages. Larger particles initiate the fusion of many macrophages into multi-nucleated giant cells for particle encasement. Macrophages are recruited into inflamed tissues from the circulating monocyte population. Approximately 10% of white blood cells are monocytes which after release from the bone marrow circulate for 2–3 days, before being recruited into tissues as inflammatory macrophages or undergoing apoptosis. Circulating MRP8/14 (S100A8/A9) is a measure of monocyte recruitment, part of the monocyte-endothelial docking complex, and shed during monocyte transmigration across the endothelium. The higher the S100A8/A9 the more monocytes being recruited giving an indirect measure of debris production.

Introduction

The advantages of metal on metal (MOM) hip replacement are decreased wear rate, preservation of bone stock, anatomical restoration and enhanced stability. Large amounts of metal wear particles and metal ions are released which may induce adverse reactions including local soft tissue toxicity, hypersensitivity reactions, bone loss and risk of carcinogenesis. Aseptic loosening can be the result of a peri prosthetic osteolysis generated as a result of a biological response to particulate wear debris.

Our aim in this study was to determine whether a steeply inclined acetabular component would give rise to a higher concentration of metal ions.

INTRODUCTION

The advantages of large diameter metal on metal total hip arthroplasty (MoM THA) and hip resurfacing arthroplasty are decreased wear rate, preservation of bone stock, anatomical restoration and enhanced stability. Large amounts of metal wear particles and metal ions are released which may induce adverse reactions including local soft tissue toxicity, hypersensitivity reactions, bone loss and risk of carcinogenesis. Aseptic loosening can be the result of a peri-prosthetic osteolysis generated as a result of a biological response to particulate wear debris.

No reports in the literature exist as to whether circulating levels of Chromium (Cr) and Cobalt (Co) decrease upon removal of a symptomatic large diameter MoM implant or whether levels remain high due to the effect of metal ions debris left behind in the soft tissues after revision surgery.

Introduction

Some patients with Cerebral Palsy who had a de-rotation osteotomy performed for correction of excessive anteversion had persistence of internal foot progression even after surgery. Potential causes which have been implicated include: weak hip abductors, spasticity of the anterior fibres of the gluteus medius, hip adductor spasm and persistent femoral anterversion. The aim of this study was to see if there is any relationship between significant abductor weakness [less than Grade III: MRC] and persistence of internal foot progression.

The availability and usage of portable image intensifiers has revolutionised routine orthopaedic practice. Many procedures have become simpler, easier, less invasive and less time-consuming. Extensive use of fluoroscopy can, however, result in significant radiation exposure to operating staff. An accumulated dose of 65 (Sv after multiple exposures has been reported to increase the risk of thyroid cancer many years later. Previous studies have shown that it is possible to exceed this dose during various orthopaedic procedures. Though thyroid shields are extensively available most orthopaedic surgeons do not use them. The present study was aimed at measuring the scattered dose to thyroid during DHS/IMHS for neck of femur fractures and IM nailing for long bone fractures and thereby emphasise the need for operating theatre personnel to wear a thyroid shield.

A prospective study of 32 consecutive procedures was carried out. The EDD Unfors dosimeter was used to measure the tissue specific exposure dose to thyroid. Measurements were also obtained from the mobile C-arm fluoroscope unit, which calculated the total number of images and the total dose and duration of radiation for each procedure. Other factors including the grade of surgeon, the total number of theatre personnel wearing the lead gown and/or the thyroid shield and the duration of surgery were also recorded.

In 32 procedures, the dose of 65 (Sv was exceeded 13 times; 8 times during DHS/IMHS and 5 times during IMN. The average thyroid dose was 142 (Sv during IMN and 55 (Sv during DHS. Only 9 of 223 (4%) theatre personnel were using a thyroid shield in spite of its availability. The results suggest that the thyroid is frequently exposed to potentially harmful radiation during these procedures. Strict inclusion of a thyroid shield as a part of routine radiation protection is recommended.

Purpose: The aim of this study was to see if there is any relationship between a positive hamstring shift test, which is a measure of knee flexion deformity after eliminating pelvic tilt with anterior pelvic tilt during the gait cycle.

Methods: We included all patients with cerebral palsy who had a gait analysis and a full physical assessment including measurement of the popliteal angle and hamstring shift test between August and December 05. The difference in measurement of knee flexion between the popliteal angle at 90 degrees and the hamstring shift test was termed hamstring length (HL). There were 33 patients of which 9 [18 limbs] were selected who fulfilled the criteria of a significant positive hamstring shift [> 10 degrees difference]. Maximum dynamic hip extension and average pelvic tilt were estimated from the gait analysis graph. SPSS13.0 was used to analyse the data.

Results: Mean HL was found to be 15.28 degrees. 6 (33.3%) patients had average pelvic tilt < 5 degrees, 8 (44.4%) was between 5–10 degrees and 4 (22.2%) patients had pelvic tilt of more than 10 degrees. The data had a normal distribution. There was no co relation between HL and pelvis tilt [p value:0.363 and r= −0.228.] or between average anterior pelvic tilt and the hip fixed flexion deformity. (p=0.361). However, it was found that maximum dynamic hip extension had strong negative association with average pelvic tilt (p=0.05, r = −0.455).

Conclusion: This study suggests that hamstring shift test does not have any correlation with pelvic tilt. In patients with a positive hamstring shift test, correcting the pelvic tilt will not correct the flexion deformities of the knee.

Purpose: Some patients with Cerebral Palsy who had a de-rotation osteotomy performed for correction of excessive anteversion had persistence of internal foot progression even after the surgery. The aim of this study was to see if there is any relationship between significant abductor weakness [less than Grade III: MRC] and persistence of internal foot progression.

Methods: We included all ambulatory patients with cerebral palsy who had had a de-rotation osteotomy between the periods of 2000 – 2005, who had also had a pre and post operative gait analysis, assessment of anteversion, muscle charting and hip range of movements. There were 12 patients [17 hips, 5 bilateral] 5 male 7 female with an average age of 13. Seven were diplegic, two hemiplegic and three had asymmetric diplegia. Data was assessed using SPSS 13.0. As the data was found to be normally distributed the Fisher exact test and the Spearman’s Co-relation Coefficient was used.

Results: Of the 17 limbs operated, preoperative femoral anteversion was 20–60 degrees [mean: 45] and post op femoral anteversion was 0–35[mean: 15]. Of these 7 hips had persistent internal rotation gait on gait analysis. None of these patients with persistent internal rotation had any hip capsular contractures, and there was no significant change in abductor power after surgery. On testing the hypothesis it was found that there is no relationship between weak hip abductors and persistent internal rotation. [Fisher exact test: p value: 0.8, r = −0.07]

Conclusion: Weak abductors may not be a cause of persistent internal rotation following de-rotation osteotomy. Weak abductor power is not a contraindication to de-rotation osteotomies and do not affect outcome of surgery.

Aim: To investigate the versatility of ßexible intramedullary nails (FIN) in the surgical treatment of forearm fractures in children. Methods: 28 children were treated using FIN for displaced forearm fractures over a period of 5 years. There were 18 boys and 10 girls. The mean age was 11.5 years and the mean follow up were 7.9 months. Two nails were used one each for radius and ulna. 12 children were operated for unstable displaced fractures, 14 were operated after failed initial reduction and 2 were operated for open fractures. 16 were nailed by closed method, 12 had mini open technique in cases of failed initial closed reduction. The nails were removed on an average of 6–8 months. Results: All the children achieved bony union in excellent position. The average time for union was 5.6 weeks. All but 2 patients had full range of movements and none had any functional difþculty. 3 children had transient hypo aesthesia in the area of superþcial radial nerve distribution and one child developed compartment syndrome which needed fasciotomy. There were no long term sequel. Conclusions: Use of FINs in paediatric forearm fractures should be encouraged when surgical intervention is needed. They are axially and rotationally stable. They are safe to introduce and remove at a later date. Their ßexibility allows remodelling of the fracture and growth of the long bones.

Aim: The Computer Assisted Orthopaedic Surgical System [CAOSS] is designed to assist the surgeon in performing the task of accurate placement of the distal locking screws via a trajectory that is planned by one AP and Lateral image from the conventional C-Arm. Methodology: Two near orthogonal x-ray images containing the distal femur with the registration phantom and including the distal end of the nail with the two locking holes are obtained using a standard C Arm and then processed after distortion correction. The phantom is supported by an end effector, which is continuously tracked in 3D space by an overhead camera. Features of interest are extracted and the image registered in 3D space through the evaluation of the phantomñs projection. A computer-based model of the anatomical region is developed and the position of the screws planned. Even if the distal locking hole image is not a true circle, the software is robust enough to detect the difference in curvature of the upper and lower part of the ellipse and thus calculate the necessary angle at the time of insertion. Once the trajectory is accepted, the surgeon implements the plan by moving a passive manipulator arm, while receiving visual positional cues from the computer in the form of a targeting screen. When the targeting is complete; the arm is locked in position and the trajectory implemented. Two individuals used the device for distal locking of Richards intra medullary femoral nail in several saw bone models. Results and Conclusions: Successful locking was accomplished in all cases by using the trajectory planned using one AP and Lateral image. This was the case even when the image was not a true lateral of the locking hole. The results of this study using this new versatile system, including the number of x-rays required, duration of x-ray exposure and time for distal targeting and locking are presented.

Aims: Dynamic hip screw for intertrochanteric fractures is one of the most common procedures performed by orthopaedic surgeons. The prerequisite for proper placement of the implant is accurate insertion of the guide wire. The Computer Assisted Orthopaedic Surgical System [CAOSS] is designed to assist the surgeon by planning the trajectory based on one intra-operative AP and Lateral image from a C-Arm. Methodology: After closed reduction on the fracture table, two near orthogonal x-ray images containing the proximal femur with the registration phantom are obtained using a standard C-Arm and then processed after distortion correction. The phantom is supported by an end effector, which is continuously tracked in 3D space. Features of interest are extracted and the image registered in space through the evaluation of the phantom’s projection in the x-ray image. The versatility of the CAOSS is increased by the provision allowing the adjustment of the planned trajectory to the surgeon’s satisfaction. Once the trajectory is accepted, the surgeon implements the plan by moving a passive manipulator arm, while receiving visual positional cues from the computer in the form of a targeting screen. When the targeting is complete; the arm is locked in position and the trajectory implemented. Results: We present the results of the pilot clinical study involving 10 patients using this device. The results obtained were compared with an equal number of patients randomly selected from the complete neck of femur database, who had undergone a conventional DHS placement, during the last one-year. Accuracy of placement of the implant was assessed by an independent observer and by a previously validated computer program that assesses the accuracy from scanned post operative X-rays. The average targeting time was 6 minutes and overall there was no significant difference between the two groups.

Introduction: Virtual Reality arthroscopic training systems offer the potential for improved training, assessment and evaluation of surgical skills. Of the various virtual reality arthroscopic training systems available, the main limiting factors preventing their use as a standard training tool is the lack of force feedback. No force data is available from in vivo measurements, which would serve as the basis for the development of such a system. Methodology: We attached a six axis force torque (FT) sensor to a standard arthroscopic probe while at the same time making necessary modiþcations to meet the safety and sterility requirements, and measured in vivo the forces and torques generated during various standard tasks of a routine knee arthroscopy. [The procedure was split into 11 separate tasks] A simultaneous video recording of the procedure was made and synchronized to the force torque recording by using an audio signal. A pilot study to evaluate the difference between experienced and less experienced arthroscopists was also undertaken. Results and conclusions: For comparison and evaluation purposes the vectored XY torque recording was used. Comparison between junior and senior arthroscopic surgeons was done by assessing the XY Torque distribution over time and evaluation of the graph patterns generated while performing similar tasks. Though differences can be seen, it did not show any statistical signiþcance. Successful completion of an arthroscopic procedure requires adequate visualization and gentle manipulation of instruments and tissues within the knee. The use of a force torque sensor in arthroscopic training systems will allow detection of and warn when excessive potentially damaging forces are being used. This will provide a means for improving training as well as a method of evaluation, including revalidation.