The stability of an external ring fixator using trans-osseous wires is determined by the number of wires per ring, their tension and their configuration. Ideally a crossing angle of 90° in the centre of the bone provides the greatest stability. This is however rarely possible due to the restrictions imposed by safe anatomical corridors. The Taylor Spatial Frame is a hexapod structure which relies on 6 connecting struts attached to fixed tabs on the ring; the Ilizarov system allows connecting rods to be placed in any available spaces. The aim of this study was to identify differences in wire placement using the TSF compared with the standard Ilizarov ring. Method: Cross-sectional anatomical diagrams of the tibia were taken from 3 levels. Lines representing wires were drawn crossing at the centre of the bone. The maximum crossing angles for an Ilizarov ring using safe anatomical corridors were calculated. A TSF ring was then superimposed on the image and angles recalculated taking into account impedance caused by the strut tabs. The angles were compared using a Students t-test taking p=0.05 as significant. Results: The average maximum crossing angle of the Ilizarov wires was 61° compared with 36° for the TSF. At all 3 levels the angles were found to be significantly different (p=0.002). Discussion: Limitations in the trans-osseous wire placement has implications for construct stability and therefore function. This may force the surgeon to make greater use of half pins, or more wires. We have shown significant differences in pin placement using the TSF which should be taken into consideration when using the system

Lower back pain (LBP) is a worldwide clinical problem and a prominent area for research. Numerous in vitro biomechanical studies on spine specimens have been undertaken, attempting to understand spinal response to loading and possible factors contributing to LBP. However, despite employing similar testing protocols, there are challenges in replicating in vivo conditions and significant variations in published results. The aim of this study was to use the University of Bath (UoB) spine simulator to perform tests to highlight the major limitations associated with six degree of freedom (DOF) dynamic spine testing.

A steel helical spring was used as a validation model and was potted in Wood's metal. Six porcine lumbar spinal motion segments were harvested and dissected to produce isolated spinal disc specimens. These were potted in Wood's metal, ensuring the midplane of the disc remained horizontal and then sprayed with 0.9% saline and wrapped in saline-soaked tissue and plastic wrap to prevent dehydration. A 400N axial preload was used for spinal specimens. Specimens were tested under the stiffness and flexibility protocols.

Tests were performed using the UoB custom 6-axis spine simulator with coordinate axes. Tests comprised five cycles with data acquired at 100Hz. Stiffness and flexibility matrices were evaluated from the last three motion cycles using the linear least squares method.

According to theory, inverted flexibility matrices should equal stiffness matrices. In the case of the spring, the matrices matched analytical solutions and inverted flexibility matrices were equivalent to stiffness matrices. Matrices from the spinal tests demonstrated some symmetry, with similarities between inverted flexibility- and stiffness matrices, though these were unequal overall. Matrix element values were significantly affected by displacements assumed to occur at disc centre.

Spring tests proved that for linear, elastic specimens, the spine simulator functioned as expected. However, multiple factors limit the confidence in spine test results. Centre of rotation, displacement assumptions and rigid body transformations are known to impact the results from spinal testing, and these should be addressed going forward to improve the replication of in vivo conditions.

Aim

A septic revision of an artificial joint is routinely split up in a so-called dirty phase and a clean phase. The measures taken to initiate the start of the clean phase vary significantly between musculoskeletal infection centers. We performed simulations of one-step exchanges of infected THAs and sought to 1) determine the effect of different clean phase protocols on the sterile field, and 2) determine whether or not it is possible to re-implant the new prosthesis completely clean.

Patient perceptions regarding the functional outcomes and return to sports after shoulder replacement are often pessimistic, with many patients presenting for shoulder replacement surgery after months or years of avoiding the procedure so they could continue to live the current life they have, despite the increasing pain and dysfunction. Less common, but becoming more frequent, patients present with expectations that they will be able to return to all activities including heavy resistance training, cross-fit, rock climbing, and other strenuous overhead sports. In the past, little information has been available regarding the activities of shoulder arthroplasty patients after surgery. Typically, the boundaries have been set by the surgeon, with many patients cautioned or even prohibited from overhead sports, weight training, or heavy work responsibilities. A typical set of guidelines may include no repetitive overhead sports, except for recreational swimming, and no lifting over 20 pounds. Golf, jogging, hiking and other activities are allowed.

The origin of these restricted guidelines and expectations is unknown, but many believe that since the results of shoulder replacements are less favorable in younger patients, it may be due to the overuse or abuse of the shoulder joint that is more typical at a younger age. Others have suggested that common sense prevails and that an artificial joint made of metal and plastic has a finite number of total movements and tolerance to resistance activities, and therefore keeping these activities at a minimum would extend the longevity of the artificial joint. None of these concepts are backed up by evidence-based literature, essentially reflecting the personal bias of the surgeons who care for patients with these problems. Despite all of the sophisticated research, scoring scales, outcome measures, and value-based metrics, the only outcome that really matters is whether the patient can return back to their normal way of life, at home, at work, during sport, or any activity that is important to them.

Recent studies of patients who have had joint replacement surgery have revealed that our patients who participated in sports and work activities before surgery have a strong predilection to returning to those activities after successful shoulder replacement. The most common sports that shoulder arthroplasty patients enjoy including golf, swimming, tennis, but may also include many other choices including fitness activities, rowing, skiing, basketball, and softball. As expected, the return to these sports is less for reverse shoulder arthroplasty patients vs. anatomic shoulder arthroplasty patients. In a systematic review, more than 90% of anatomic shoulder replacement patients returned to sport, while 75% of reverse shoulder arthroplasty patients returned to some sporting activity. This may reflect the constraints of the reverse prosthesis, or, quite possibly reflect the typically older age and more sedentary lifestyle of patients who are indicated for reverse shoulder arthroplasty. In addition, if the patient had a preoperative expectation of return to recreational and sports activities as part of their normal way of life, their final results demonstrated better overall outcomes.

Shoulder arthroplasty surgeons should be concerned about the outcomes desired by our patients, and the results that provide true value to their lives. We are now more aware of the activities that they are going to return to, whether we recommend restrictions or not.

Purpose

The correction obtained in the coronal plane knee deformity using guided growth was assessed in children with sick physes (Height<1SD of the normal children) to define the limits of this technique in sick physis

Arthoscopic biopsy provides adequate tissue for most diagnostic requirements. Examination of endoarticular tissue can assist in the diagnosis of some joint infections; sometimes cultures of synovial tissue may be positive even when blood and synovial fluid cultures have been negative. In chronic infections such as tuberculosis and fungal disease, and characteristic synovial lesions, such as granuloma, it may be advised. Both gout and pseudo-gout can demonstrate tophus-like deposits in synovial tissue. Synovial biopsy can have a major role in the diagnosis of synthetic arthritis after ACL reconstruction with synthetic ligaments to identify a foreign body granulomatous reaction to particulate material implant or to verify the arthroplasty effect after loosening of a knee prosthesis.

There is a lack of association between arthroscopic findings and clinical laboratory and radiological features of arthritis. The general diagnosis of rheumatoid arthritis (RA) is usually based on characteristic clinical, radiological and serological manifestations. Synovial biopsy in RA is not normally required for diagnosis because the appearance is not specific, but it may provide important prognostic information. Synovial chondromatosis and pigmented villonodular synovitis are tumours of the synovial membrane that require biopsy for diagnosis. The biopsy of articular cartilage is useful to evaluate the capacity of chondrocytes to proliferate and to test the regeneration of cartilage after resurfacing by autologous chondrocytes implantation or other techniques. Histological confirmation could improve the prognosis of the knee during arthrofibrosis (percentage of elastic fibres), fibrosis of Hoffa disease and cyclop lesion. Another application is study of ligamentisation phenomena after anterior cruciate reconstruction and the presence in osteoarthritic knees with degenerative changes in posterior cruciate ligament.

INTRODUCTION

This study investigates the relationship between direct measurement of outcome and patient report of that outcome via the OKS. The stability of this relationship over time following surgery is also assessed.

Ankle arthroscopy is generally performed through anterior portals and provides good access to the anterior aspect of the ankle joint. However, the structure of the talus and the anatomical confines of the ankle joint limit access to posterior structures via this approach.

Developments in the technique of posterior ankle arthroscopy have determined the appropriate site for portals with minimal risk of iatrogenic neurovascular injury. This facilitates treatment of conditions such as flexor hallucis longus (FHL) release, excision of os trigonum for posterior impingement, treatment of retro-calcaneal bursitis and treatment of ankle and subtalar joint pathology.

Posterior ankle arthroscopy is a relatively new technique and has recently been adopted by the senior author. This study was performed to explore the benefits and limitations of this procedure and to identify early post operative results.

We describe our experience of this technique in treating 9 patients with varied posterior ankle pathology. 2 patients had excision of os trigonum; 2 had FHL release; 1 had both excision of os trigonum and FHL release; 3 had curettage for posterior osteochondral defect (OCD) of the talus; and 1 had resection of Haglund’s deformity. The mean pre-operative AOFAS scores (Ankle-Hindfoot Scale) was 73 (range 47 to 85). The mean post operative AOFAS score at 3 months was 82 (range 75 to 87). 4 patients had recent surgery and await follow up. There were no complications. Two cases exposed the limitations of this procedure: Incomplete resection of (i) a Haglund’s deformity required conversion to an open excision and (ii) a posteromedial OCD lesion will require further anterior ankle arthroscopy due to inadequate exposure.

We conclude that for the experienced arthroscopic surgeon this is a safe technique that facilitates treatment of a variety of ankle and hindfoot problems that would otherwise require open procedures.

Aims: In recent years, radiation crosslinking has become an important processing step in the manufacture of ultra-high molecular weight polyethylene (PE) components of joint replacement prostheses due to its associated high wear resistance. Gamma or electron beam radiation treatment is usually followed by a heating step, either complete melting or annealing of PE close to but below the melting temperature for a specific time duration. The heat treatment is performed to decrease free radical concentration within the crystalline lamellae in order to make PE more oxidation resistant.

In this study, we hypothesized that high pressure processing of PE would be advantageous if it is performed only after irradiation and quenching of free radicals and that it would be detrimental if it preceded irradiation. We used accelerated oxidation, mechanical tests and wear tests to show

Methods: Ram-extruded rod stock of GUR 1050 PE (Ticona, Bayport, TX) was purchased from MediTECH Medical Polymers (Fort Wayne, IN) and machined into cylinders to snugly fit into a custom-built high-pressure cell. A Carver hydraulic press was used to apply a pressure of 500MPa to PE specimens preheated to various temperatures, slow cooled to room temperature followed by pressure release. The PE cylinders and untreated control PE were subjected to 50kGy gamma radiation, which is a dose sufficient for a high degree of crosslinking in PE. A Parr bomb reactor filled with oxygen gas and operating at 5atm pressure and 70_C temperature was used to oxidize PE for a period of 14 days, according to ASTM standard F2003–02, and later characterized using Fourier Transform Infrared Spectroscopy (FTIR). A second batch of PE was first irradiated, melted and then subjected to high pressure processing. ASTM standard tensile tests were conducted to determine whether there was any increase in mechanical properties. Scanning electron microscopy (SEM) and differential scanning calorimeter (DSC) were used to characterize the lamellar morphology.

Results: The morphological characterization techniques, SEM and DSC, showed that high pressure processing increased the crystallinity as well as lamellar thickness regardless of whether the process was conducted prior to or after irradiation. FTIR showed that there was a monotonic increase in oxidation with lamellar thickness if the irradiation was carried out after high pressure processing. Several mechanical properties such as modulus and yield stress of PE increased with increase in crystallinity, which is desirable for applications where PE is subjected to high stresses.

Conclusions: High-pressure processing benefits the mechanical properties of crosslinked PE when it is conducted after irradiation and melting. However, if it conducted prior to irradiation and is not followed by thermal treatment, it can lead to more trapped free radical and excessive oxidation. Therefore, it is important to employ this processing method after irradiation so that it improves the mechanical properties of crosslinked PE.

Introduction

Patients who undergo hip resurfacing, total hip arthroplasty (THA), and total knee arthroplasty (TKA) are frequently assessed post-operatively using objective scoring indices. A small yet significant percentage of these patients report specific unfulfilled functions following surgery, indicating unmet expectations. The purpose of this study was to examine the types of functional deficits reported for each class of surgery, how frequently these limitations occur, and the demographic of patients who experience/report these limitations.

Introduction:

Total knee arthroplasty (TKA) should aim to adjust the component gap (CG) difference between extension and flexion. However, this difference cannot be measured without placement of a femoral component. The bone gap reportedly decreases in extension after component setting. In contrast, it may be possible to use the mean value of the CG difference in several patients to adjust femoral resection amount beforehand. The purpose of this study is to evaluate the technique of adjusting CG difference using the mean values with measured resection technique (MRT) in TKA.

Purpose of the study: Computer assisted surgery for total knee arthroplasty is widely used in Europe. The reliability of these systems appears to be very good with bone cuts within 3° of the planned mechanical axis. Nevertheless, the relationship between intraoperative measurements provided by the navigation system and the postoperative gonometry can be used to assess the quality of realignment. The purpose of this work was to determine this relationship.

Material and methods: Thirty-three knees operated on with the Navitrack® system were assessed. Two senior operaters performed all procedures. An Omnia® cemented prosthesis with an ultracongruent fixed plateau was used in all cases. Intraoperative measurements wer made with the definitive prosthesis after cement solidification without stress on the knee. Postoperative gonometry was undertaken when the intraoperative flexion had disappeared six weeks to six months after the operation. Gonometric measurements were made by an independent operator using a computerized system operating on digitalized x-rays. The gonometric protocol had been standardized previously and only the gonometric measurements in compliance with this protocol were retained for analysis. The difference between measurements was analyzed with the t test for paired variables. Search for correlations was also performed.

Results: On average the intraoperative deviation was 0.8±0.8° (3° valgus to 2.4° varus). The postoperative gonometry showed 1.7±1.1° (3.4° valgus to 4.3° varus). The mean difference between the intraoperative axis and the measured postoperative axis was significant (p< 0.0001). There was no significant correlation between intraoperative and postoperative measurements.

Discussion: Computer-assisted navigation systems have their limitations which should be measured. The present findings would demonstrate a significant difference of minimal amplitude between the intraoperative measurement and the postoperative gonometry. Although the clinical pertinence of this difference remains to be demonstrated, it must be kept in mind for safe use of these navigation systems.

Purpose of the study: Posterior glenoid erosio is a common finging in patients with degenerative joint disease of the shoulder. Anterior release is usually recommended, almost always with correction of the glenoid retroversion. There is no real consensus on the gravity of these posterior lesions nor on the appropriate attitude. The purpose of this study was to define the limitations of asymmetrical reaming during correction of excessive glenoid retroversion during total shoulder arthroplasty.

Material and methods: Five fresh cadaver shoulders were used. The size of the glenoid cavity and the humeral head were measured to select the optimal size for the glenoid implant. The scapula was embedded in resin. Posterior glenoid erosion was created by reaming to simulate wear producing retroversion greater than 15°. A control computed tomography (CT) was obtained to verify the lesion. The glenoid cavity was then prepared in the same manner as for prosthesis implantation, restoring neutral version to enable implantation of the prosthetic component of the size initially determined. A second CT was obtained to confirm the correction of the retroversion.

Results: The retroversion was corrected in all cases. At least one point of the implant penetrated the glenoid wall in all cases. In three cases, four points were outside the wall. In one case, reaming caused a fracture of the anterior glenoid rim. Finally, in one case, the size of the implant had to be reduced to avoid an oversized implant.

Discussion: The limitations for asymmetrical reaming to correct for posterior wear yet leave enough bone stock for implantation of a glenoid prosthesis are not defined. This study shows that asymmetrical reaming of the anterior rim of the glenoid cavity cannot satisfactorily correct for glenoid retroverson greater than 15° because of the frailness of the anterior wall and the risk the points will penetrate the rim. These complications compromise the primary stablity of the prosthesis and probably secondary short-term and mid-term stability.

Conclusion: If the glenoid retroversion is excessive (> 15°), it would be advisable to graft the posterior defect.

Objective of the study is to determine to what extent patients experience more limitations 1–5 years after revision total hip arthroplasty (THA) compared to patients after primary THA, and if this is accompanied by a reduction in physical activity behavior. Five hundred and six patients were included: 372 primary and 134 revision THA. Questionnaires were used to measure limitations and physical activity. Linear regression analysis showed that patients after revision surgery report significantly more, clinically relevant limitations compared with primary THA patients, but did not show a significant difference in mean total minutes of physical activity per week. Physical activity behavior appeared to be similar for primary and revision THA patients. The results stress the importance of determining different aspects of recovery after THA.

Background: Numerous radiographic indices have been described to help define the degree of acetabular deficiency in adult patients with developmental dysplasia. The lateral centre-edge angle (LCE) of Wiberg and the anterior centre-edge (ACE) angle of Lequesne are two of the commonly measured indices that are reported in the evaluation of procedures that are used to correct acetabular deformity. Unfortunately much of the reported literature that tries to define abnormal indices has been extrapolated from the evaluation of “normal” pelvi or those with osteoarthritis. The purpose of this study was to evaluate the application and limitations of the LCE and ACE angles in a group of patients with developmental dysplasia treated with periacetabular osteotomy.

Methods: 50 cases were randomly selected from a larger cohort of over 500 patients with acetabular dysplasia treated at our institution with periacetabular osteotomy. The preoperative and post osteotomy false profile and anteroposterior plain radiographs were reviewed. Cases were first grouped into one of three categories based on a general estimation of the location of acetabular deficiency as determined from the AP radiograph.

A number of radiographic indices were measured and compared including the VCE angle, LCE angle, and acetabular angles of Tönnis and Sharp. Variation in both the VCE and LCE angle was evaluated by measuring the index using two different reference points. This included (1) the traditional mark of the furthest point along the sclerotic density of the weight bearing zone and (2) an alternate point representing the furthest extent of lateral or anterior bony coverage. Additional sources of measurement error were determined. The relationships between the centre-edge angles and other radiographic indices were determined. An evaluation of the indices and correction on post osteotomy radiographs was also performed.

Results: Fifty cases in 45 patients were reviewed. There were 31 female and 19 males. The mean age was 30 years (range, 17–45). A general review of all preoperative AP radiographs revealed that all hips displayed some degree of lateral deficiency.

Nineteen of these cases displayed a “classic” lateral and anterior deficiency. However, 19 cases displayed a more uniform deficiency and 12 cases were in fact retroverted.

Evaluation of the radiographic indices revealed:

A mean VCE angle of 2.3 degrees (SD±12.7) and LCE angle of 3.4 degrees (SD±9.3). These were corrected to 25.8 degrees (SD±11.6) and 28.6 degrees (SD±8.7) following osteotomy.

Potential sources of error in measurement that were identified include:

Deformity of the acetabulum and occasional abnormalities of the femoral head limit the ability to identify the center of the rotation necessary to measure the centre-edge angles. Subluxation of the femoral head also creates a degree of error. These difficulties were observed in over 20% of cases.

Conclusion: Centre-edge indices can be useful parameters in defining acetabular morphology. However, these parameters should not be used in isolation and the absolute values do little to define the overall location and degree of deficiency in hips with acetabular dysplasia. A number of significant sources of measurement error limit their accuracy especially in patients with hip dysplasia. Currently, it is our feeling that no single radiographic parameter fully defines the specific morphology in each individual case nor reflects the success of correction when treating patients with periacetabular osteotomy.

Background

Self-rated disability scores in patients with chronic LBP (cLBP) do not always relate well to performance in traditional physical tests (e.g. back strength, fatigability, etc.). Therefore tests using “functional activities” that challenge for example trunk mobility and movement speed have been suggested as alternative “objective” outcome measures. We examined the relationship between self-reported disability and a battery of such functional tests.

Aims

Patient engagement in adaptive health behaviours and interactions with their healthcare ecosystem can be measured using self-reported instruments, such as the Patient Activation Measure (PAM-13) and the Effective Consumer Scale (ECS-17). Few studies have investigated the influence of patient engagement on limitations (patient-reported outcome measures (PROMs)) and patient-reported experience measures (PREMs). First, we assessed whether patient engagement (PAM-13, ECS-17) within two to four weeks of an upper limb fracture was associated with limitations (the Quick Disabilities of the Arm, Shoulder and Hand questionnaire (QuickDASH), and Patient-Reported Outcome Measurement Information System Upper Extremity Physical Function computer adaptive test (PROMIS UE PF) scores) measured six to nine months after fracture, accounting for demographic, clinical, and psychosocial factors. Secondly, we assessed the association between patient engagement and experience (numerical rating scale for satisfaction with care (NRS-C) and satisfaction with services (NRS-S) six to nine months after fracture.

Aims

The purpose of this study was to identify factors associated with limitations in function, measured by patient-reported outcome measures (PROMs), six to nine months after a proximal humeral fracture, from a range of demographic, injury, psychological, and social variables measured within a week and two to four weeks after injury.

A statement of the purposes of the study

This study examined the stability of two different hexapod frames at increasing strut angles and the possible use of an additional strut to aid stability.