Occlusal loading and muscle forces during mastication aids in assessment of dental restorations and implants and jaw implant design; however, three-dimensional bite forces cannot be measured with conventional transducers, which obstruct the native occlusion. The aim of this study was to combine accurate jaw kinematics measurements, together with subject-specific computational modelling, to estimate subject-specific occlusal loading and muscle forces during mastication.

Motion experiments were performed on one male participant (age: 39yrs, weight: 82kg) with healthy dentition. Two low-profile magnetic sensors were fixed to the participant's teeth and the two dental arches digitised using an intra-oral scanner. The participant performed ten continuous of chewing on a polyurethane rubber sample of known material properties, followed by maximal compression (clenching). This was repeated at the molars, premolars of both the left and right sides, and central incisors. Jaw motion was simultaneously recorded from the sensors, and finite element modelling used to estimate bite force. Specifically, simulations of chewing and biting were performed by driving the model using the measured kinematics, and bite force magnitude and direction quantified. Muscle forces were then evaluated using a rigid-body musculoskeletal model of the patient's jaw.

The first molars generated the largest bite forces during chewing (left: 309 N, right: 311 N) and maximum-force biting (left: 496 N, right: 495 N). The incisors generated the smallest bite forces during chewing (75 N) and maximum-force biting (114 N). The anterior temporalis and superficial masseter muscles had the largest contribution to maximum bite force, followed by the posterior temporalis and medial pterygoid muscles.

This study presents a new method for estimating dynamic occlusal loading and muscle forces during mastication. These techniques provide new knowledge of jaw biomechanics, including muscle and occlusal loading, which will be useful in surgical planning and jaw implant design.

Total temporomandibular joint (TMJ) replacements reduce pain and improve quality of life in patients suffering from end-stage TMJ disorders, such as osteoarthritis and trauma. Jaw kinematics measurements following TMJ arthroplasty provide a basis for evaluating implant performance and jaw function. The aim of this study is to provide the first measurements of three-dimensional kinematics of the jaw in patients following unilateral and bilateral prosthetic TMJ surgeries.

Jaw motion tracking experiments were performed on 7 healthy control participants, 3 unilateral and 1 bilateral TMJ replacement patients. Custom-made mouthpieces were manufactured for each participant's mandibular and maxillary teeth, with each supporting three retroreflective markers anterior to the participant's lip line. Participants performed 15 trials each of maximum jaw opening, lateral and protrusive movements. Marker trajectories were simultaneously measured using an optoelectronic tracking system. Laser scans taken of each dental plate, together with CT scans of each patient, were used to register the plate position to each participant's jaw geometry, allowing 3D condylar motion to be quantified from the marker trajectories.

The maximum mouth opening capacity of joint replacement patients was comparable to healthy controls with average incisal inferior translations of 37.5mm, 38.4mm and 33.6mm for the controls, unilateral and bilateral joint replacement patients respectively. During mouth opening the maximum anterior translation of prosthetic condyles was 2.4mm, compared to 10.6mm for controls. Prosthetic condyles had limited anterior motion compared to natural condyles, in unilateral patients this resulted in asymmetric opening and protrusive movements and the capacity to laterally move their jaw towards their pathological side only. For the bilateral patient, protrusive and lateral jaw movement capacity was minimal.

Total TMJ replacement surgery facilitates normal mouth opening capacity and lateral and inferior condylar movements but limits anterior condylar motion. This study provides future direction for TMJ implant design.

Falls in adults are a major problem and can lead to injuries and death. In order to better understand falls and successful recoveries, identifying kinematics, kinetics, and muscle forces during recovery from loss of balance is crucial. To obtain reactive gait patterns, participants must be subjected to unexpected perturbations such as trips and slips. Previous researchers have reported kinetics recovery data following stumbling; however, the muscle force recovery patterns remain unknown. To better target exercises to reduce the risk of falls, we must first understand which muscles, their magnitude, and their coordination patterns, play a role in a successful recovery from a trip and a slip. Additionally, knowing the successful patterns of lower limb function can help with the diagnosis of faulty movements.

A total of 20 healthy adults in their twenties with similar athletic backgrounds were perturbed on a split-belt treadmill using Computer-Assisted Rehabilitation Environment (Motkforce Link) at a preset speed of 1.1m/s. Two kinds of perturbations were administered: slip and trip. Slips were simulated by accelerating one belt, whereas trips were simulated by decelerating one belt. Both perturbations had similar intensity and only differed in the direction. Computational modeling was used to obtain lower-limb function during the compensatory step. SPM paired t-test was used to compare differences in recovery strategies between slip and trip through magnitude and patterns of joints.

There were no significant differences in joint angles post tripping vs post-slipping. Results of net joint moments showed that compensating for the loss of balance due to tripping required a higher ankle plantarflexion moment than slipping (at 22-52%; 1.2± 0.3vs0.4±0.2, p<0.001). Additionally, larger gluteus maximus (at 40-50%;8.7±3.8vs2.7±1.1N/kg, p=0.001), gluteus medius (at23~33%; 22.6±5.7vs6.8±3.6N/kg, p<0.001) were generated than post-slipping, respectively.

These findings suggested that greater GMAX and GMED forces are required post-trip recovery than slip. Future analysis of trip recovery showed the importance of ankle joint in recovering from forward and backward fall. These results can be used as references in remote diagnosis of joint and muscle weakness and assessment of the risk of falls with the use of accelerometers.

Background of study

Following the Montgomery ruling, consent is now a matter of law. The medical professionals have to show proof that risks and implications and material risks are explained to the patient and that they have accepted to go ahead with surgery.

Background of study

Medial patellofemoral ligament (MPFL) reconstructions are often performed using gracilis autografts, this can be associated with donor site morbidity and complications. The use of synthetic material can circumvent a harvest operation and have previously been demonstrated to be effective in other types of reconstructive procedures and may be effective in MPFL reconstruction. We report our experience and clinical results with the use of FiberTape (FT) in MPFL reconstruction and compare it to the same surgical technique using standard autografts.

There is an increasing trend towards radial head replacement (RHR) or fixation for complex radial head fractures. These injuries are identified by grossly displaced fragments or elbow instability. The aim of this study was to examine the outcome of a surgical protocol that emphasised delayed radial-head excision (RHE) as the procedure of choice. When the humero-ulnar joint was congruent, intervention was delayed 10 to 14 days to allow time for ligamentous healing. RHR was performed if instability was demonstrated on-table.

A retrospective study was performed to identify the outcome of patients undergoing surgery for a radial head fracture between 2008 and 2014. There were 18 Mason Type III and 18 Mason Type IV injuries. There was an associated coronoid fracture in 17 patients. RHE was performed in 28 patients, of which the reoperation rate was 2 (7.1%). RHR was performed in 15 patients, of whom 4 (27%) had reintervention. RHR was most common in the Type III coronoid fractures. The cumulative reoperation rate was 9.3% at six months and 15.4% at two years. The median Oxford Elbow Score (OES) was 85.4 (IQR 73.4 to 99.5). Time from injury was the only predictor of the Oxford Elbow Score (p=0.04).

This surgical protocol resulted in a reduced need for RHR, a low reintervention rate, and satisfactory function. RHR should be reserved for cases where stability cannot be achieved on-table. Stability can be maximised by delaying RHE until early ligamentous healing occurs.

We retrospectively reviewed 44 consecutive patients (50 hips) who underwent acetabular re-revision after a failed previous revision that had been performed using structural or morcellised allograft bone, with a cage or ring for uncontained defects. Of the 50 previous revisions, 41 cages and nine rings were used with allografts for 14 minor-column and 36 major-column defects. We routinely assessed the size of the acetabular bone defect at the time of revision and re-revision surgery. This allowed us to assess whether host bone stock was restored. We also assessed the outcome of re-revision surgery in these circumstances by means of radiological characteristics, rates of failure and modes of failure. We subsequently investigated the factors that may affect the potential for the restoration of bone stock and the durability of the re-revision reconstruction using multivariate analysis.

At the time of re-revision, there were ten host acetabula with no significant defects, 14 with contained defects, nine with minor-column, seven with major-column defects and ten with pelvic discontinuity. When bone defects at re-revision were compared with those at the previous revision, there was restoration of bone stock in 31 hips, deterioration of bone stock in nine and remained unchanged in ten. This was a significant improvement (p <  0.001). Morselised allografting at the index revision was not associated with the restoration of bone stock.

In 17 hips (34%), re-revision was possible using a simple acetabular component without allograft, augments, rings or cages. There were 47 patients with a mean follow-up of 70 months (6 to 146) available for survival analysis. Within this group, the successful cases had a minimum follow-up of two years after re-revision. There were 22 clinical or radiological failures (46.7%), 18 of which were due to aseptic loosening. The five and ten year Kaplan–Meier survival rate was 75% (95% CI, 60 to 86) and 56% (95% CI, 40 to 70) respectively with aseptic loosening as the endpoint. The rate of aseptic loosening was higher for hips with pelvic discontinuity (p = 0.049) and less when the allograft had been in place for longer periods (p = 0.040).

The use of a cage or ring over structural allograft bone for massive uncontained defects in acetabular revision can restore host bone stock and facilitate subsequent re-revision surgery to a certain extent.

Cite this article: Bone Joint J 2014;96-B:319–24.

The TruFit® plug is a cylindrical scaffold designed to bridge defects in articular cartilages. It is a porous structure with interconnected pores, which gives it the capability of providing a framework for the ingrowth new tissue and remodelling to articular cartilage and bone.

The aim of this study was to assess the radiological incorporation of TruFit® Plugs using MRI. Between December 2007 & August 2009, 22 patients underwent treatment of a chondral or osteochondral lesion using one or more TruFit Plugs. At a minimum of 2 years, 10 patients (12 lesions) were MRI scanned and assessed with a modified MOCART Scoring system by an independent Consultant Musculoskeletal Radiologist. 8 patients were no longer contactable and 4 patients declined MRI as their knee was asymptomatic.

8 of 12 lesions showed congruent articular cartilage cover with a surface of a similar thickness and signal to the surrounding cartilage and reconstitution of the subchondral bone plate. 2 lesions had a thicker congruent articular surface with a similar signal to the surrounding articular cartilage without restoration of the subchondral bone plate. 2 lesions showed no graft incorporation at all and were filled with granulation tissue. Full incorporation of the bony portion of the plug had occurred in only 3 lesions with partial incorporation in 7 lesions. The remaining portion of these 7 lesions looked cystic on MRI.

The MRI appearances of the TruFit® Plug at 2 years are encouraging with the majority (83%) showing good restoration of the articular surface with tissue of similar thickness, congruity and signal as the surrounding articular cartilage. However complete incorporation of the TruFit® Plug is rare and cystic change is common. The significance of this cystic change is not clear.

Introduction

Perthes' disease is associated with coxa breva, plana and magna, and a high riding prominent greater trochanter causing abductor shortening and weakness, leg shortening and extra-articular impingement. A trochanteric advancement with an infero-lateralising oblique sliding osteotomy of the proximal femur would lengthen femoral neck, improve abductor length and strength, relieve impingement and improve leg length. We assessed the mid-term outcomes for this procedure.

Introduction

Patients who are symptomatic with concurrent acetabular dysplasia and proximal femoral deformity may have Perthes disease. Osteotomies to correct both the acetabular and proximal femur deformities may optimise biomechanics and improve pain and function. In this study, we assessed the long-term results for such a combined procedure.

Introduction

Patients who are symptomatic with concurrent acetabular dysplasia and proximal femoral deformity may have Perthes disease. Osteotomies to correct both the acetabular and proximal femur deformities may optimise biomechanics and improve pain and function. In this study, we assessed the long-term results for such a combined procedure.

Introduction

Perthes disease is associated with coxa breva, plana and magna, and a high riding prominent greater trochanter causing abductor shortening and weakness, leg shortening and extra-articular impingement. A trochanteric advancement with an infero-lateralizing sliding osteotomy of the proximal femur would lengthen femoral neck, improve abductor length and strength, relieve impingement and improve leg length. We assessed the mid-term outcomes for this procedure.

Background

Despite studies into patient consent and their understanding of the potential risks of trauma surgery, no study has looked at the patient's understanding of the procedure involved with neck of femur fracture surgery.

Introduction

Many patients who had previous proximal femoral osteotomies develop deformities that may not be amenable to total hip replacement (THR) with standard off-the-shelf femoral stems. Previous studies have shown high revision rates (18% at 5–10 years follow-up). Computer-assisted-design computer-assisted-manufacture (CAD-CAM) femoral stems are indicated but the results are not known. We assessed the clinical results of THR using CAD-CAM femoral stems specifically for this group of patients.

Introduction

Brachial plexus blocks are used widely to provide intra-operative and post-operative analgesia. Their efficacy is well established, but little is known about discharging patients with a numb or weak arm. We need to quantify the risk of complications for improved informed consent.

Introduction: The objective for this study was to assess the long term results for minor column allograft used in revision hip arthroplasty.

Methods: We prospectively included patients undergoing acetabular cup revision using minor column allograft with a minimum of 5 years follow-up. Minor column allograft was used in uncontained acetabular bone defects of sizes between 30% and 50% of the acetabulum. Acetabular failures requiring re-revisions at any time after surgery were included. Acetabular failure for any cause requiring re-revision surgery was used as end-point. Graft failure was considered when re-revision required the concurrent use of structural bone graft, metal augments or excision arthroplasty for any cause.

Results: There were 65 cases that met the study criteria. We included 5 deaths with a mean follow-up of 11.9 years (6.8–14.8) and 10 losses to follow-up after a mean follow-up of 11.7 years (5.3–17.4). Twenty eight acetabulum failed, with 14 occurring before 5 years at a mean of 1.8 years (0.1–4.8) and 14 occurring after 5 years at a mean of 12.2 years (5.6–23.2). Causes included aseptic loosening (23), infection (2), dislocation (1), graft non-union (1) and cup fracture (1). Fourteen grafts failed, with 8 occurring before 5 years at a mean of 1.2 years (0.5–4) and 6 occurring after 5 years at a mean of 11.3 years (6–23.2) after surgery. The mean improvement in modified Harris Hip Scores was 32.3 at 1 year and 32.6 at last follow-up assessment. The cup survivorship was 56.9 % and graft survivorship 78.5 % at a mean follow-up of 16.3 years (5.3–24.8).

Discussion: Metal augments have been used in revision arthroplasty for low demand patients but we recommend the use of minor column allografts in higher demand patients who are more likely to require further revision surgery.

Purpose: An Osteochondral defect in the knees of young active patients represents a challenge to the orthopedic surgeon. Early studies on allogenic cartilage transplantation showed this tissue to be immunologically privileged, showed fresh grafts to have hyaline cartilage, and surviving chondrocytes present several years after implantation.

Method: Since January 1978 until October 1995 we enrolled 72 patients in a prospective non-randomized study of fresh osteochondral allografts in our institute. Ten international patients which were lost to follow-up were excluded. The major indications for the procedure were: patients younger than 60 years of age having post-traumatic unipolar defects larger than three cm in diameter and one cm in depth.

Results: Sixty two patients, ages 11–57 (mean 28) were followed for 15–31 years (mean 20.4 years). The etiology for the osteochondral defect was traumatic injury to the knee in 41 patients (66%), Osteochondritis Dissecans in 15 patients (24%), and in six patients (10%) due to other pre-existing conditions. Twenty of the 62 grafts have failed, with five having graft removal and 15 converted to total knee replacement. Three patients died during the course of this study due to unrelated causes. The Kaplan-Meier survivorship analysis showed: 92%, 79%, 56%, and 49% graft survival at 10, 15, 20, and 25 years respectively, (median survival = 23 years). Patients with surviving grafts had good function, with a modified Hospital for Special Surgery score of an average 88 at 20 years or more following the allograft transplantation surgery.

Conclusion: Through this long term study the authors confirm the value of fresh osteochondral allografts as a long term solution for large articular defects in the knees of young patients. The improvement of patients’ outcome compared to the previous published results of our earlier studies could be attributed to improved surgical techniques and increasing expertise of the senior authors. We therefore recommend the use of fresh osteochondral allografts for treatment of large osteochondral defects in the distal femur of young and active patients.

Skeletal metastases are an increasing sequaelae for patients with a wide range of neoplastic lesions owing to the increasing incidences of cancer. The diagnosis of a skeletal metastasis is, however, at present a terminal diagnosis representing uncontrolled tumour dissemination. The metastatic destruction of the bone reduces its load bearing capabilities progressing to the principle orthopaedic complication, that of complete loss of cortical integrity.

Aim: We examine the population suffering a complication of skeletal metastasis in terms of their mortality and morbidity. We compare patients who underwent surgical stabilization as a result of a fracture through a metastatic lesion against those who underwent prophylactic stabilization.

This is a retrospective study of all patients within the Cardiff centre who underwent an operation for a metastatic bone lesion over a 10 year period (n=140). The patients were identified using pathological records created when samples were sent at the time of the operations. The patients were all followed up for a minimum of 24 months. The demographics of the patients were collected and a detailed analysis of the primary tumour, the surgical procedure, the mobility, and survival of the patients was undertaken. The patients data was then cross referenced with the database at the regional cancer centre and the post operative radiotherapy treatment regimen were collected.

Patients who underwent prophylactic surgical stabilization had a significant survival advantage compared to those stabilized following a fracture (p=0.002). The morbidity postoperatively, defined by the patients functional mobility, also shows the benefits of prophylactic stabilization with significantly improved mobility when compared to the mobility following fracture stabilization (p=0.033). It has also been shown that there is a significant postoperative survival benefit for those patients who were able to regain mobility (p< 0.01).

Our results show a significant survival benefit of prophylactic fixation rather than fixation following fracture which is in line with previous studies We have also, for the first time in a large number study, shown that there is a survival benefit for patients who are able to mobilize following surgery and if prophylactic stabilization was undertaken patients were significantly more mobile postoperatively.

We evaluated 31 patients with bilateral dysplastic hips who had undergone periacetabular osteotomy for early (Tönnis grade 0 or 1) or moderate (Tönnis grade 2) osteoarthritis in one hip and total hip replacement for advanced (Tönnis grade 3) osteoarthritis in the other. At a mean follow-up of 5.5 years (2 to 9) after periacetabular osteotomy and 6.7 years (3 to 10) after total hip replacement, there was no difference in the functional outcome in hips undergoing osteotomy for early or moderate osteoarthritis and those with a total hip replacement, as determined by the Merle d’Aubigné and Postel score and the Western Ontario and McMaster Universities osteoarthritis index. More patients preferred the spherical periacetabular osteotomy to total hip replacement (53% vs 23%; p = 0.029). Osteoarthritis secondary to hip dysplasia is often progressive. Given the results, timely correction of dysplasia by periacetabular osteotomy should be considered whenever possible in young patients since this could produce a favourable outcome which is comparable with that of total hip replacement.

Elevated serum cobalt and chromium ion levels associated with carcinogenesis and chromosomal damage in animals have raised concerns that metal-on-metal (MOM) total hip replacement (THR) in humans may produce the same effects over time. Considering that the risks may be related to the level of these ions in the body, this study compared the serum cobalt and chromium ion levels in patients with unilateral versus bilateral 28 mm diameter MOM THR.

All patients having THR at our institution were prospectively registered on a computerised database. From our database, we identified 108 patients with Ultima (Johnson and Johnson, Leeds) MOM THR with 28 mm bearing made of cobalt-chromium alloy. After patient review in clinic and before blood results were known, patient matching was performed by date after surgery at blood sampling, activity level and body mass. Using these stringent criteria, 11 unilateral THR could be adequately matched with 11 bilateral THR. Blood serum was taken with full anti-contamination protocols and serum analysed via inductively coupled plasma mass spectrometry.

The serum cobalt ion level after unilateral MOM THR was 4.4 times normal (median 22 nmol/L, range 15 to 37 nmol/L) compared to 8.4 times normal (median 42 nmol/L, range 19 to 221 nmol/L) for bilateral MOM THR (p=0.001). The serum chromium ion level after unilateral MOM THR was 3.8 times normal (median 19 nmol/L, range 2 to 35 nmol/L) compared to 10.4 times normal (median 52 nmol/L, range 19 to 287 nmol/ L) for bilateral MOM THR (p=0.04).

This study has shown that the serum cobalt and chromium ion levels in patients with bilateral MOM THR are significantly higher than those in patients with unilateral MOM THR. With levels of up to 50 times the upper limit of normal, this finding may be of relevance for the potential development of long-term side effects.