Aims

Total knee arthroplasty (TKA) is a common and safe orthopaedic procedure. Zimmer Biomet's NexGen is the second most popular brand of implant used in the UK. The primary cause of revision after the first year is aseptic loosening. We present our experience of using this implant, with significant concerns around its performance with regards early aseptic loosening of the tibial component.

Total knee arthroplasty (TKA) is a common orthopaedic procedure with over 1,500 done in 2016 in Ireland alone. 96% of all TKAs are due to pain in the knee associated with osteoarthritis. According to the UK National Joint Registry (NJR), there is a 0.47%, 1.81%, 2.63% and 4.34% probability risk of undergoing a revision TKA within one, three, five and ten years respectively post-index surgery. A variety of reasons for failure of TKA have been described in the literature including infection, aseptic loosening, pain, instability, implant wear, mal-alignment, osteolysis, dislocation, peri-prosthetic fracture and implant fracture. The NexGen Posterior Stabilised Fixed has NJR revision rates of 0.44%, 1.61% and 2.54% at years one, three and five respectively. A retrospective review was carried out of 350 NexGen TKAs that were performed directly by, or under the supervision of, a fellowship trained arthroplasty surgeon in a dedicated orthopaedic hospital between April 2013 and December 2015. 26 (7.4%) of these were revised as of 31 December 2017. Three were for septic arthritis with the remaining 23 (6.6%) for aseptic loosening. Patients typically started to experience symptoms of medial tibial pain with supra-patellar swelling from a combination of effusion and synovial thickening at 12–24 months. Inflammatory markers were normal in all cases. Radiographs of symptomatic knee replacements showed bone loss on the medial tibia with a tilt of the tibial component into a varus alignment. The high number of revisions of this particular prosthetic has led to its use being discontinued at this centre.

Background: Early failure of morselized impaction bone allograft is usually due to shear forces. Soil mechanics tells us that in aggregates such as bone allograft, the resistance to these shear forces can be increased by altering the fluid concentration, varying the particle size, and improving the morphology of the graft particle. Finding an idealized concentration of fat and water in bone graft could improve the resistance to interparticle shear and therefore decrease the failure rate of impaction bone graft. Ensuring the quality of the bone source is adequate can also improve the initial strength the bone graft. Furthermore optimizing the graft can be achieved by screening methods and simple intra-operative techniques.

Methods: Human femoral heads were retrieved from both total hip arthroplasty and hemiarthroplasty procedures. Bone mineral density was determined by DEXA scanning. The fat and water content of the graft was varied by combinations of squeezing and drying the graft and also by washing the graft using pulse lavaged water and 1:1 mixture of chloroform: methanol. The amount and characteristics of the fat and water in human morselized cancellous bone was quantified by the Karl Fischer extraction techniques, and gas chromatography. The overall shear strength of each graft preparation was determined by the direct shear test, adapted from an accepted protocol in soil mechanics and the optimum mixture which would resist shear forces was determined.

Results: An optimum level of fat and water was determined which was 50% stronger than unaltered bone graft. This is most closely approximated in an operating theatre situation by washing the graft with pulse lavaged normal saline and subsequently squeezing the bone graft in a vice with a force of 335kPa for 5 minutes. Whereas osteoarthritic and osteoporotic bone were similar in their fat and water content and initial resistance to shear forces, after processing, the resistance to shear forces of osteoarthritic bone improved by 147% and that of osteoporotic bone only improved by 12% (p< 0.001) Conclusions: Optimizing the fat and water content of bone graft and closely choosing the source of graft produces a stronger graft which is more resistance to shear stresses, protecting the surgical construct until bone growth can occur.

Background: Infection remains the single most devastating complication of joint arthroplasty. In cases of established prosthetic infection, where implant retention is not feasible, there is limited consensus on an optimum management protocol.

Aim: To assess the outcome of revision for infected hip prostheses using a novel treatment regimen.

Materials and Methods: Retrospective study of a consecutive case series of 40 patients with late chronic hip joint prosthetic infection treated by a single surgeon over a 4 year period. The mean interval between index arthroplasty and revision for infection was 40 months, with patients having prior symptoms of infection for a mean of 22 months.

The treatment protocol consisted of a two stage exchange with removal of infected components via a posterior approach incorporating an extended trochanteric osteotomy, insertion of an interim antibiotic eluting cement spacer and re-implantation of an extensively coated uncemented prosthesis on the femoral side. Systemic antibiotic treatment following each stage consisted of an abridged course of 5 days post operative intravenous administration followed by complete cessation of anti-microbial therapy. The mean interval between implant removal and re-implantation was 111 days.

Results: At a mean follow up of 29.6 months (minimum 12 months), there were 2 cases of recurrent prosthetic infection. Dislocation following the second stage occurred in 7 patients. There was one mortality and one case of post operative sciatic nerve palsy. The Harris hip score increased from a pre-operative mean of 43.8 to a post operative mean of 83.9. At follow up, no patient had required revision for aseptic loosening or mechanical instability on the femoral side

Conclusion: The combination of effective staged surgical joint debridement, a shortened post operative course of systemic antibiotic treatment and an adequate latent period before re-implantation has led to encouraging early results in this series of revised chronic hip joint prosthetic infections.

A new apparatus and technique of syndesmosis fixation is tested in a prospective clinical study. Buttons on both sides of the ankle anchor a strong suture under tension following syndesmosis reduction. This syndesmosis suture acts like a tightrope when under tension. Implantation is simple with a minimally invasive technique, as the medial side is not opened. It allows physiological micromotion whilst resisting diastasis, does not require routine removal, and allows patients to weight-bear earlier.

Sixteen patients with Weber C ankle fractures with a syndesmosis diastasis underwent suture-button fixation and the results compared to 16 consecutive patients with syndesmosis screw fixation. Patients were, in effect, quasi-randomised according to surgeon preference. Mean A,O,F,A,S, ankle scores were significantly better in the suture-button group at three months post-op (91 vs 80, p=0.01, unpaired t-test) and at twelve months (93 vs 83, p=0.04, unpaired t-test). Return to work was also significantly faster (2.6 months vs 4.6 months, p=0.02, unpaired t-test). No suture-buttons required implant removal. Axial CT scanning at three months showed implants to be intact with maintenance of reduction, as compared to the uninjured contralateral side.

Suture-button syndesmosis fixation is simple, safe and effective. It has shown improved outcomes and faster rehabilitation, without needing routine removal. Although the apparatus design may undergo further refinement, we believe this technique will become the treatment of choice in Weber C ankle fractures with a syndesmosis injury.

Waste disposal is an issue that affects us all. The amount and toxicity of medical waste has increased in line with increasing medical facilities and diagnostic and therapeutic procedures. Demand for landfill sites and increasing household and hospital waste loads, have made the current situation untenable. New thinking and new strategies must be employed

To investigate waste production in the operating department during a primary total hip arthroplasty.

A prospective observational study, waste from packaging and non-clinical materials in fifty consecutive total hip replacements. Weight, volume, cost of disposal and percentage of recycled items were recorded. Inappropriate segregation of waste was recorded and the hazards involved are discussed.

Domestic waste is compressed and buried at a cost of €222($383)/tonne. This extrapolates into a cost of about €1,500($2,589) yearly in the region and over €10,000($17,000) in Ireland. Cost to the environment, 2.6 tonnes locally, and 18.9 tonnes of surgical waste/year. Biological waste buried at €880 ($1,518)/tonne.

Reduce, Reuse and Recycle are the cornerstones of waste management. Medical staff need to understand how best to segregate waste and take advantage of opportunities for reuse and recycling. We must revisit the packaging of implants, the use of recycled paper.

We have developed a comprehensive system of assessment of patients undergoing total hip and total knee replacement. This new unified scoring system provides a single instrument to measure the disability of patients suffering from primary osteoarthritis of either hip or knee. This instrument will be used to prioritize these patients for a single waiting list and it will be used as an outcome measure to assess their progress after their hip or knee replacement surgery. The scoring system is comprised of two parts carrying equal point value. The subjective part is an assessment tool completed by the patients themselves. It is comprised of 12 Items covering every aspect of the disability associated with hip and knee arthritis. The objective part is an assessment tool completed by the treating physician or a trained joint arthroplasty nurse.

The first stage of this project comprised of formulation of a preliminary questionnaire after a thorough assessment of 50 patients suffering from hip or knee arthritis. We then organised multiple clinical sessions with focus groups to critically appraise the content of our new questionnaire. The focus group patients were invited to give their comments about any issues not discussed previously. This preliminary questionnaire was then converted into a set of closed questions and was divided into a subjective and an objective part.

The second stage of this project involved assignment of scales and scale grading for different components of the objective part. This involved the process of magnitude estimation. 75 patients, 25 consultants and 5 nurses were involved in this process.

The third stage of this project involved a comprehensive assessment of this new scoring system in terms of internal consistency, internal consistency reliability, inter-observer reliability, test-retest reliability, face validity, content validity and construct validity. The process of validation involved comparison of our scoring system with the relevant parts of SF36, Oxford knee score, WOMAC and AIMS. It has also been tested on the first subset of post operative patients to measure its responsiveness. Cronbach’s alpha was used for internal consistency and Pearson’s correlation coefficients were used for different correlation studies.

Our new scoring system has shown a very satisfactory internal consistency. The inter-rater agreement and the test-retest reliability data on the first set of 100 patients are very promising as well. The instrument has shown a significant effect size in the first set of post-op patients 4 months after their surgery.

Our new scoring system will provide an easy to apply and comprehensive instrument for a need based waiting list for patients undergoing either THR or TKR. It will also be a reliable and sensitive outcome measure to monitor these patients’ progress in the post-operative period.

Introduction A new technique of ankle syndesmosis fixation is proposed. Buttons are placed on both sides of the ankle, connected by a strong non-absorbable suture. The technique is simple and minimally invasive: a medial incision is not required. It resists diastasis whilst allowing physiological micromotion and does not require routine removal.

Methods The technique was tested on a cadaver model of a Maisonneuve injury under increasing torque loads. Sixteen embalmed cadaver legs were randomised to receive suture-button fixation or four-cortical 4.5 mm syndesmosis screw fixation. A prospective clinical study involving 16 patients with Weber C fractures and syndesmosis diastasis is presented. They underwent suture-button fixation and the results were compared to 16 consecutive patients with syndesmosis screw fixation.

Results In the cadaver study, both groups had similar rates of diastasis following torque loading. However, the suture-button did give a more consistent performance: standard deviations were significantly lower (p=0.001) than the screw group. In the clinical study, both groups were evenly matched as regards patient age, male: female ratio, and fracture patterns. Mean AOFAS ankle outcome scores at three months were significantly better in the suture-button group (91 versus 82, p=0.01). No suture-button patients required implant removal. They had a faster return to work compared to the screw group (three months versus five months). Axial CT scanning performed at three months post-op showed all implants to be intact with no loss of reduction.

Conclusions Suture-button syndesmosis fixation is simple, safe, effective and physiological. It has shown improved outcomes and faster rehabilitation, without needing routine removal. It may become the treatment of choice in Weber C ankle fractures with a syndesmosis diastasis.

In relation to the conduct of this study, one or more the authors have received, or are likely to receive direct material benefits.

Aims: A new technique of syndesmosis fixation is proposed; placing buttons on both sides of the ankle, without opening the medial side, connected by a strong non-absorbable suture. We tested this against syndesmosis screw fixation in a cadaver model of a Maisonneuve injury and subsequently in a prospective clinical study. Methods: 16 cadaver legs were randomised to have suture-button or syndesmosis screw fixation and tested under torque loading. In the clinical study, 16 patients with a syndesmosis diastasis underwent suturebutton fixation and the results compared to 16 patients with syndesmosis screw fixation. Results: In the cadaver study, both groups had similar rates of diastasis, although the suture-button did give a more consistent performance: standard deviations were significantly lower (p=0.001). In the clinical study, mean A.O.F.A.S. scores at 3 months were significantly better in the suturebutton group (91 vs 82, p=0.01). No suture-button implants required removal, compared to 13/16 of the screw group (p=0.001). Conclusions: Suture-button syndesmosis fixation is simple, safe and physiological. Biomechanically it performs at least as well as screw fixation. Clinically it has shown improved outcomes, without needing routine removal. It may become the treatment of choice in syndesmosis injuries.

The infection in total joint arthroplasty in most cases is blood borne in origin, but seeding of organisms at the time of surgery is also a well recognised cause. The aim of our study was to determine the optimal timing to administer the prophylactic per-operative antibiotics in total knee arthroplasties performed under tourniquet control.

The patients were randomised in two groups “A” (18 patients), received antibiotics at the time of induction of anaesthesia and group “B” (15 patients), received antibiotics ten minutes prior to the release of tourniquet. We used the intravenous doses of Kafadol 1gm and Gentamicin 160mgs for 24 hours. The antibiotic levels were assessed using blood samples taken from the peripheral vein, operative wound (periprosthetic area) and suction drains. Both groups were well matched with regard to age, weight, sex, ASA class and number of patients.

In group “A” the antibiotic levels were lower in operative wound as compared to the peripheral vein and it continued to decline in the post operative period. In group “B” the levels were 40% higher in the samples from the operative wound and remained significantly high in post operative period, as compared to those in group “A”.

Our findings are in favour of antibiotic administration just before the release of the tourniquet in the total knee arthroplasty.

Background: We have noticed while performing total hip arthroplasty, that during skin closure, the anterior edge of the wound tends to migrate proximally in relation to the posterior edge. This result is an inaccurate approximation of the wound, the so-called ‘dogs ear’. The aims of the study were to assess and quantify the degree of migration of the anterior edge relative to the posterior one using an invisible marker and to see whether marking the incision site prior to surgery improved skin closure.

Material and methods: We included forty patients undergoing primary hip arthroplasty in the study. Prior to surgery, the skin was marked with five lines perpendicular to the incision line with an invisible skin marker using the greater trochanter as reference point. The skin was then routinely prepared with betadine and a proprietary adhesive incision drape (Ioban 2) was applied to the incision site. The surgeon performed the operation routinely and intra-operatively, the subcutaneous fat content was measured at three set points and averaged. After the wound had been closed, an ultraviolet light source was used to highlight the invisible lines. The gap between the anterior and posterior edge was measured for each line. One set of patients had their incision site marked with a visible marker on the incision drape while the other set did not.

Results: There was a persistent proximal migration of the anterior edge in relation to the posterior edge. The proximal part of the incision site had a more marked skin migration compared to the distal wound. In the unmarked group, the proximal part of the anterior edge tended to migrate on average by 9.5 mm (from 30 mm to 5 mm) in respect to the posterior edge. In the marked group, this migration was reduced to an average of 1.6 mm (from 2 mm to 0 mm) and there was a statistical difference between the 2 groups with p< 0.0001 using the independent t-test as illustrated by the table. Of note, the degree of migration did not vary with the thickness of the fat content. Also, all the wounds healed with no signs of infection.

Conclusion: From this study, we have been able to quantify objectively the extent of migration of the anterior edge of the wound in a hip incision in relation to the posterior edge. Improved hip closure following total hip replacement was achieved after marking the skin prior to surgery. We therefore recommend marking the skin pre-operatively prior to hip incision in order to achieve accurate skin closure as part of the general principle of proper wound closure.

Although there have been many studies of the epidemiology of hip fractures in the older population, including the assessment of bone density and the predictive value of a Cole’s fracture in particular for later hip fracture, there has not previously been an analysis of combined presentation of hip and upper limb fractures. We performed this study to examine the incidence and risk factors of such combined injuries and to assess the impact these have on rehabilitation and subsequent treatment in order to formulate a possible clinical pathway or treatment protocol for such patients.

The study was performed retrospectively, with all patients admitted over 3 years with fractured neck of femur being reviewed. Of the 681 patients admitted over this period of time (324 intracapsular and 357 extracapsular fractured necks of femur), 22 were found to have a contemporaneous fracture of the upper limb. The associated upper limb fractures were distal radius (n=11), olecranon (n=5) and neck of humerus (n=6), with the same ratio of intracapsular to extra-capsular fractures as the whole group. The female to male ratio in both isolated hip and combined fracture groups was the same at 3:1. The mean patient age was 77.6 years for isolated hip fractures and 78.4 for the combined group. The usual mechanism of injury in both groups was a fall onto the side, but patients in the combined group also typically described having the arm outstretched for protection. The mean total length of stay in hospital for isolated hip fracture was 10.9 days and for combined fractures was 23.2 days (p< 0.05, ANOVA). Exact details were not retrievable from the nursing homes taking some of these patients, but from the data obtained there was a trend apparent for more of the combined group to require such care and for longer. In summary, it is obvious that patients sustaining combined upper limb and hip fractures can become a significant burden on already busy hospital services. These patients therefore require an even more concerted effort at rehabilitation than those patients with isolated hip fractures. We therefore now recommend the use of a specific clinical pathway or protocol including early fixation, immediate co-ordinated multidisciplinary team involvement and rehabilitation, with everyone involved with the treatment of these patients, doctors, physiotherapists, occupational therapists and others, being aware of these extra requirements. Issues for further analysis in these patients include assessing the contribution of bone density to such double fractures, the associated risk of further fractures and therefore whether such patients require further treatment or protective measures.

Flat foot due to rupture of the tibialis posterior tendon has not previously been described in children. We present three young patients who developed unilateral pes planus after old undiagnosed lacerations of the tendon. Transfer of the flexor hallucis longus to the distal stump of the tibialis posterior tendon achieved good results in all three cases.