Introduction

External fixators are common surgical orthopaedic treatments for the management of complex fractures and in particular, the use of circular frame fixation within patients requiring limb reconstruction. It is well known that common complications relating to muscle length and patient function without rehabilitation can occur. Despite this there remains a lack of high-quality clinical trials in this area investigating the role of physiotherapy or rehabilitation in the management of these patients. We aim to complete a systematic review of rehabilitation techniques for patients undergoing external fixator treatment for Limb Reconstruction of the lower limb.

Abstract

Introduction

Computer hexapod assisted orthopaedic surgery (CHAOS) has previously been shown to provide a predictable and safe method for correcting multiplanar femoral deformity. We report the outcomes of tibial deformity correction using CHAOS, as well as a new cohort of femoral CHAOS procedures.

Abstract

Nearly a quarter of screws cause damage during insertion by stripping the bone, reducing pullout strength by over 80%. Studies assessing surgically achieved tightness have predominately shown that variations between individual surgeons can lead to underpowered investigations. Further to the variables that have been previously explored, several basic aspects related to tightening screws have not been evaluated with regards to how they affect screw insertion. This study aims to identify the achieved tightness for several variables, firstly to better understand factors related to achieving optimal intraoperative screw purchase and secondly to establish improved methodologies for future studies.

Two torque screwdrivers were used consecutively by two orthopaedic surgeons to insert 60 cortical, non-locking, stainless-steel screws of 3.5 mm diameter through a 3.5 mm plate, into custom-made 4 mm thick 20 PCF sheets of Sawbone, mounted on a custom-made jig. Screws were inserted to optimal tightness subjectively chosen by each surgeon. The jig was attached to a bench for vertical screw insertion, before a further 60 screws were inserted using the first torque screwdriver with the jig mounted vertically, enabling horizontal screw insertion. Following the decision to use the first screwdriver to insert the remaining screws in the vertical position for the other variables, the following test parameters were assessed with 60 screws inserted per surgeon: without gloves, double surgical gloves, single surgical gloves, non-sterile nitrile gloves and, with and then without augmented feedback (using digitally displayed real-time achieved torque). For all tests, except when augmented feedback was used, the surgeon was blinded to the insertion torque. Once the stopping torque was reached, screws were tightened until the stripping torque was found, this being used to calculate tightness (stopping/stripping torque ratio). Screws were recorded to have stripped the material if the stopping torque was greater than the stripping torque. Following tests of normality, Mann-Whitney-U comparisons were performed between and combining both surgeons for each variable, with Bonferroni corrections for multiple comparisons.

There was no significant (p=0.29) difference in the achieved tightness between different torque screw drivers nor different jig positions (p=0.53). The use of any gloves led to significant (p < 0 .001) increases in achieved tightness compared to not using gloves for one surgeon but made no difference for the other (p=0.38–0.74). Using augmented feedback was found to virtually eliminate stripping. For one surgeon average tightness increased significantly (p < 0 .001) when torque values were displayed from 55 to 75%, whilst for the other, this was associated with significantly decreases (p < 0 .001), 72 to 57%, both surgeons returned to their pre-augmentation tightness when it was removed.

Individual techniques make a considerable difference to the impact from some variables involved when inserting screws. However, the orientation of screws insertion and the type of screwdriver did not affect achieved screw tightness. Using visual feedback reduces rates of stripping and investigating ways to incorporate this into clinical use are recommended. Further work is underway into the effect of other variables such as bone density and cortical thickness.

Proximal humeral fractures occur frequently, with fixed angle locking plates often being used for their treatment. However, the failure rate of this fixation is high, ranging between 10 and 35%. Numerous variables are thought to affect the performance of the fixation used, including the length and configuration of screws used and the plate position. However, there is currently limited quantitative evidence to support concepts for optimal fixation. The variations in surgical techniques and human anatomy make biomechanical testing prohibitive for such investigations. Therefore, a finite element osteosynthesis test kit has been developed and validated - SystemFix. The aim of this study was to quantify the effect of variations in screw length, configuration and plate position on predicted failure risk of PHILOS plate fixation for unstable proximal humerus fractures using the test kit.

Twenty-six low-density humerus models were selected and osteotomized to create a malreduced unstable three-part fracture AO/OTA 11-B3.2 with medial comminution which was virtually fixed with the PHILOS plate. In turn, four different screw lengths, twelve different screw configurations and five plate positions were simulated. Each time, three physiological loading cases were modelled, with an established finite element analysis methodology utilized to evaluate average peri-screw bone strain, this measure has been previously demonstrated to predict experimental fatigue fixation failure.

All three core variables lead to significant differences in peri-screw strain magnitudes, i.e. predicted failure risk. With screw length, shortening of 4 mm in all screw lengths (the distance of the screw tips to the joint surface increasing from 4 mm to 8 mm) significantly (p < 0 .001) increased the risk of failure. In the lowest density bone, every additional screw reduced failure risk compared to the four-screw construct, whereas in more dense bone, once the sixth screw was inserted, no further significant benefit was seen (p=0.40). Screw configurations not including calcar screws, also demonstrated significant (p < 0 .001) increased risk of failure. Finally, more proximal plate positioning, compared to the suggested operative technique, was associated with reduced the predicted failure risk, especially in constructs using calcar screws, and distal positioning increased failure risk.

Optimal fixation constructs were found when placing screws 4 mm from the joint surface, in configurations including calcar screws, in plates located more proximally, as these factors were associated with the greatest reduction in predicted fixation failure in 3-part unstable proximal humeral fractures. These results may help to provide practical recommendations on the implant usage for improved primary implant stability and may lead to better healing outcomes for osteoporotic proximal fracture patients. Whilst prospective clinical confirmation is required, using this validated computational tool kit enables the discovery of findings otherwise hidden by the variation and prohibitive costs of appropriately powered biomechanical studies using human samples.

The screw fastening torque applied during bone fracture fixation has a decisive influence on subsequent bone healing. Insufficient screw tightness can result in device/construct instability; conversely, excessive torques risk damaging the bone causing premature fixation failure. This effect is even more prominent in osteoporotic bone, a condition associated annually with almost 9 million fractures worldwide. During fracture fixation, screw tightening torque is applied using subjective feel. This approach may not be optimal for patient”s recovery, increasing risk of fixation failure, particularly in osteoporotic bone, and potentially require revision surgical interventions.

Besides bone density, various factors influence the performance of screw fixation. These factors include bone geometry, cortical thickness and time-dependant relaxation behaviour of the bone. If the influence of screw fastening torque on the bone and relationships between these factors was better understood, the surgical technique could be optimised to reduce the risk of complications.

Within this study, we developed an axisymmetric finite element (FE) model of bone screw tightening incorporating viscoelastic behaviour of the cortical bone such as creep and stress relaxation. The model anticipated time-dependent behaviour of the bone for different bone thickness and density after a typical bone fixation screw had been inserted. The idealised model has been developed based on CT scans of bones with varying densities and inserted screws. The model was validated through a series of experiments involving bovine tibiae (4–5 months) to evaluate the evolution of surface strains with time (Ncorr v1.2). Stress distribution was assessed in photoelastic experiments using acrylic analogues. Relaxation tests have been performed in aqueous environment for up to 48 hours to ensure the relaxation would be complete. The creep behaviour (maximum principal strain) was compared against computational predictions. Our early simulations predicted relaxation strains on the surface of the bone to be 1.1% within 24 hours comparing favourably to 1.3% measured experimentally. Stress distribution patterns were in agreement with photoelastic results.

Using experimentally derived viscoelastic properties, the model has the potential to predict creep and stress relaxation patterns after screw insertion with different fastening torques for bones with varying density and geometry. We aim to develop this into a planning tool providing guidance to surgeons for optimal tightening when using screw fixation, particularly in reduced quality bone.

Background

Devices are frequently used to gain sufficient purchase in a bone so that the bone itself can be manipulated to move or rupture soft tissue attachments. During hip surgery, several different extraction corkscrews are available to remove the femoral head, each with a different screw design with no evidence to suggest which is most effective. Additionally during the use of corkscrew devices, often due to the low bone density, stripping of the screw threads out of the femoral head can occur prior to its extraction, thus requiring reinsertion. The aims of this project were to measure the primary pullout and reinsertional forces of five commercially available corkscrews.

Trauma patients have the highest risk of VTE among hospitalised patients1, with a reported 13-fold increase of risk2. Due to the heterogeneity of injuries, the true incidence of VTE in trauma patients is difficult to obtain. This study examines the incidence of VTE and associated complications in trauma patients with lower limb injuries.

Between 2005 and 2009, patients over 18 years of age with lower limb injuries and/or fractures that were either isolated or a part of multi-systemic injuries were included in the study. Further stratification was performed according to the Injury Severity Score: an ISS greater than 15 was a major (trauma); less than 15, a minor. The mode of VTE prophylaxis, type of surgery, and bleeding complications were also examined.

There were 5528 patients in the minor trauma group, and 509 in the major trauma group. Minor trauma: the mean age was 58.1 years (range: 18 – 104). The VTE incidence was 1.2%: 0.67% for DVT, and 0.5% for PE. The readmission rate within a three-month period was 11%, of which 2.8% were due to VTE with 13 cases of DVT, and 5 cases of PE. The 30-day mortality rate was 2.2%. Seven patients died from PE during admission, while one died from PE within three months after discharge.

Major trauma: the mean age was 42.5 years (range: 18 – 95). The overall VTE incidence was 7.8%: 5.9% for DVT, and 0.9% for PE. The readmission rate within a three-month period was 7.6%, of which 5% were due to VTE with 2 cases of DVT. The overall 30-day mortality rate was 11.1%, and there was no formally-diagnosed fatal PE during admission or post-discharge.

Major trauma patients had a 7-fold increased risk of developing VTE during admission when compared to minor trauma patients, although minor trauma patients had more fatal PEs. Additionally, major trauma patients had a 10-fold increased risk for DVT, and a 3-fold risk for PE, when compared with minor trauma patients. No significant difference was detected between the two groups for the 30-day readmission rate due to VTE.

This randomized clinical trial utilizing the validated rotator cuff disease specific quality of life outcome measure (RC-QOL) and adequate power demonstrates no difference in outcome for full thickness rotator cuff tears comparing open to mini-open surgical techniques.

The purpose of the study was to compare standard open rotator cuff repair versus mini-open rotator cuff repair by measuring the disease specific quality of life in patients with rotator cuff injury.

This randomized clinical trial utilizing a validated disease specific outcome measure and adequate power demonstrates no difference in outcome for full thickness rotator cuff tears comparing open to mini-open surgical techniques.

The miniopen approach utilizing an arthroscoic acromioplasty provides no additional beneifit to the patient undergoing a rotator cuff repair.

The mean one year RC-QOL score for the open and mini-open groups were 85.3 (SD = 15.6) and 87.4 (SD = 12.0) out of a maximum of one hundred, respectively. This difference was not statistically significant (p = 0.572).

Seventy-two patients (forty-eight males/twenty-four females) with an average age of 56.4 years (thirty-three to eighty-two years) consented to participate in the study. Inclusion criteria involved: unremitting pain, failed conservative treatment of at least three months, weakness of rotator cuff, and positive diagnostic imaging indicating a full-thickness rotator cuff tear. Massive rotator cuff tears were excluded.

Prior to surgery, patients were randomized to either open or mini-open rotator cuff repair. Patients were assessed and outcomes were collected at three, six and twelve months after surgery. Primary Outcome Measure: Patient quality of life was quantified using the validated disease specific, reliable and responsive Rotator Cuff Quality of Life Questionnaire (RC-QOL) measured on a one hundred point visual analogue scale format. Secondary Outcomes: Range of motion, strength, American Shoulder and Elbow Surgeons Score, and the Shoulder Rating Questionnaire.

Introduction A prospective cohort study was conducted to assess the incidence of venous thromboembolism (VTE) in 300 patients undergoing elective spinal surgery. Although this subject has been extensively studied in patients undergoing joint replacement surgery, the true incidence of VTE related to spinal surgery remains unknown. We also sought to assess the efficacy of various forms of VTE prophylaxis, another area which has not been adequately studied.

Methods Bilateral lower extremity venous duplex scans were performed pre-operatively, within one week postoperatively and at 4 to 6 weeks post-operatively. Information was collected regarding age, gender, body mass index, type and duration of surgical procedure, intra-operative blood loss and blood transfusion, pre- and post-operative mobility and other risk factors for VTE. All patients received vigorous mechanical prophylaxis with 56% of patients receiving pharmacological prophylaxis (unfractionated or low molecular weight heparin) according to surgeon preference.

Results The overall incidence of post-operative deep vein thrombosis (DVT) was 3.4%. The incidence in those receiving pharmacological prophylaxis was 1.2% versus 6.3% in those who received mechanical prophylaxis alone (p< 0.05). Just under half of the post-operative DVTs (1.4%) occurred after hospital discharge with none of these patients receiving heparin. There were two cases of pulmonary embolism (0.7%), both occurring during hospitalization, and there were no deaths. There was no difference in blood loss or transfusion rates between patients receiving or not receiving pharmacological prophylaxis and there were no serious complications related to blood loss. There was a surprisingly high incidence of abnormalities detected on pre-operative scanning, with DVT occurring in 3.0% and superficial thrombophlebitis in 24.8%.

Discussion The incidence of DVT in patients after spinal surgery was 3.4% and was significantly lower (1.2 %) in patients who received pharmacological prophylaxis. Given that the rates of bleeding-related complications were not different between the two groups, we conclude that it is both efficacious and safe to use pharmacological prophylaxis in combination with mechanical prophylaxis routinely in patients undergoing spinal surgery. A 27.8% incidence of pre-operative venous abnormalities may reflect pre-operative immobility due to pain in this group of patients, and justifies the use of ultrasound scanning as an important pre-operative screening tool. In addition, the high incidence of late-onset DVT justifies the need for follow-up scanning several weeks after discharge. This study is the amongst the largest of its type to date, however a larger, randomized and controlled trial is now necessary to confirm these results and allow the formulation of unambiguous guidelines for spinal surgery and VTE prophylaxis.

Aim: To determine that the aetiology of cord compression in mucopolysaccharidoses (MPS) type VI. To illustrate the variability of this complication of mucopolysaccharidoses even within families. To report the youngest MPS VI patient yet described with spinal cord compression and to present the technique and results of spinal stabilisation.

Method: The course, clinical findings and management of three patients with MPS VI and two with MPS IV were reviewed.

Results: The patients with MPS VI demonstrated that the pathogenesis of spinal cord compression in this condition is complex, with elements of joint instability, bony disease and soft tissue compression. Two of the patients with MPS VI are siblings: the younger sibling was 30 months old when she required surgery. She is the youngest reported patient with this complication of MPS VI. The patients with MPS IV are presented to illustrate similarities and differences in the pathogenesis of the same problem in the two disorders. Results of cervical spine stabilisation were found to be satisfactory.

Conclusions: In both MPS IV and MPS VI spinal cord compression may be multi-factorial. This complication of the mucopolysaccharidoses needs to be considered even when the patient is very young.