Introduction

The trapezio-metacarpal joint (TMCJ) is subject to constant multiplanar forces and is stabilised by the bony anatomy and ligamentous structures. Ligament reconstruction can correct the hypermobility and potentially prevent osteoarthritis. Eaton and Littler proposed a surgical technique to reconstruct the volar ligamentous support of this joint. In our cadaveric biomechanical study, we aimed to evaluate the resultant effect of this technique on the mobility of the thumb metacarpal.

The aim of this study was to compare the results of Matti-Russe (MR) procedure and interpositional techniques (IT) in the management of scaphoid non-union.

50 scaphoid non-unions were included in this retrospective study. Demographics, initial management of fracture, location of non-union, time to surgery, procedure done and immobilisation time were recorded. Radiographs were analysed for union and deformity correction. Functional outcome was analysed using the Herbert's grading system.

The mean age and time to surgery were 26.7 years and 15.9 months. Twenty-one patients had the MR procedure and twenty-nine patients had interpositional procedures with internal fixation. DISI was present in 17 patients. The mean postoperative change in the scapholunate angle with the MR procedure was 7.9° compared to 8.0° (p>0.05) for the IT procedures. Union rate was 76% for both procedures. The mean follow-up was 9.9 months. Functional results were Herbert 0 or 1 in 42 cases.

The only significant prognostic variables were location of non-union and time to surgery. Similar deformity correction was achieved using both IT and MP procedures. MP procedure can be used in the management of scaphoid non-union even in the presence of deformity with good functional results.

Background

The optimal treatment for symptomatic elbow osteoarthritis remains debatable especially in patients still involved in heavy manual work. The Outerbridge-Kashiwagi (OK) procedure has been used when simple measures fail. The aim of this study is to analyse the results of the OK procedure in patients with symptomatic osteoarthritis.

Introduction

Only a few studies have assessed the outcome of ulnar nerve decompression, most comparing various forms of decompression. A review of the case notes of patients undergone ulnar nerve decompressions was undertaken looking at the pre-op symptoms, nerve conduction studies, the co-morbidities, operative procedures and the post-operative outcomes.

Introduction

The aim of this study is to analyse the effect of the degree of coverage of the Total Elbow implant with cement and the significance of cementation index as a predictor of failure.

Various authors have linked hypermobility at the trapeziometacarpal joint to future development of arthritis. When examining hypermobility, the anterior oblique ligament (AOL) and ulnar collateral ligament (UCL) are the two most important supporting structures. Literature suggests that reconstructive techniques to correct the hypermobility can prevent subsequent development of osteoarthritis. Eaton and Littler proposed a surgical technique to reconstruct the ligamentous support of this joint in 1973. This cadaveric biomechanical study aimed to evaluate the resultant effect on the mobility of the thumb metacarpal following this reconstructive technique. Seventeen cadaveric hands were prepared and strategically placed on a jig. Movements at the trapeziometacarpal joint were created artificially. Static digital photographs were taken with intact AOL and UCL at trapeziometacarpal joint (controls), for later comparison with those after sectioning of these ligaments and following Eaton-Littler reconstructive technique. The photographic records were analyzed using Scion.Image. Statistical analysis was performed using Minitab. A paired T-test was used to establish statistical relevance. Results confirmed that the AOL and UCL had a major role in limiting excessive motion at the trapeziometacarpal joint, principally in extension. Division of these ligaments produced a significant degree of subluxation of the metacarpal at this joint with thumb in neutral position (p-value = 0.013). Reconstruction of the ligamentous support using the Eaton-Littler technique reduced the degree of extension available (p-value = 0.005). This study confirmed the important role of the AOL and UCL in maintaining trapeziometacarpal joint stability, and that the Eaton-Littler reconstructive technique reduces the degree of hyperextension at this joint.

Shoulder arthroplasty is the treatment of choice for a range of degenerative diseases. However, long term follow-up suggests almost half of patients graded their treatment as unsatisfactory. Component malalignment is thought the most likely cause. The anterior anatomical neck is used as a reference for the osteotomy. The objective of the study was to analyse the cartilage/metaphyseal interface to identify reference points that may recover version accurately.

Twenty-four humeri were scanned using a Microscribe digitiser and surface laser scanner. Modelling software was used to analyse the Cartilage/metaphyseal interface. The retroversion angle was calculated for the normal geometry and for the standard osteotomy. An ideal osteotomy plane was then created for each specimen and the distance from the cartilage/metaphyseal interface determined, identifying points of least deviation. The reference points were used to simulate a new osteotomy for which retroversion was calculated. The novel osteotomy and traditional osteotomy were compared to the normal geometry.

The mean retroversion for the normal geometry was 18.5±9.0 degrees. The mean retroversion for the traditional osteotomy technique was 29.5±10.7 degrees, significantly different from the original (p<0.001). The mean retroversion using the novel osteotomy was 18.9±8.9 degrees and similar to the normal geometry (p=0.528).

The traditional osteotomy resulted in a mean increase in retroversion of 38%. The increase in version may result in eccentric loading at the glenoid and alter rotator cuff balance. The novel osteotomy resulted in more accurate recovery of head geometry and may improve clinical outcome.

The anterior portion of the anatomical neck is used as a reference for the osteotomy in shoulder arthroplasty. Resection at this level is thought to remove a segment of a sphere which can accurately be replaced with a prosthetic implant. The objective of the study was to analyse the cartilage/metaphyseal interface relative to an ideal osteotomy plane to define points of reference the may recover retroversion accurately. Data were collected from 24 humeri using a novel technique, combining data acquired using a Microscribe digitiser and surface laser scanner. Rhinocerus NURBS modelling software was used to analyse the Cartilage/metaphyseal interface. The retroversion angle was calculated for the normal geometry and for the standard osteotomy along the anterior cartilage/metaphyseal interface. An ideal osteotomy plane was then created for each specimen and the perpendicular distance from the cartilage/metaphyseal interface was determined, identifying points of least deviation. The reference points were used to simulate a new osteotomy for which retroversion was calculated. Paired t-tests were used to compare the novel osteotomy and traditional osteotomy to the normal geometry. The mean retroversion for the normal geometry was 18.5±9.0 degrees. The mean retroversion for the traditional osteotomy technique was 29.5±10.7 degrees, significantly different from the original (p< 0.001). The mean retroversion using the novel osteotomy was 18.9±8.9 degrees and similar to the normal geometry (p=0.528). The traditional osteotomy resulted in a mean increase in retroversion of 38%. The increase in version may result in eccentric load on the glenoid, an alteration to the rotator cuff balance and poor clinical outcome. The novel osteotomy based on points identified around the cartilage/metaphyseal interface that deviated least from an ideal osteotomy plane resulted in more accurate recovery of head geometry. The novel technique may improve clinical outcome. Further investigation is warranted.

Introduction

Ulnar nerve entrapment is the second most common nerve entrapment syndrome of the upper extremity. Despite this, only a few studies have assessed the outcome of ulnar nerve decompression. The objectives of the study were to review the pre-operative symptoms, nerve conduction studies, the co-morbidities, operative procedures undertaken and the post-operative outcomes; and investigate and ascertain prognostic factors particularly in cases of persistence of symptoms after the surgery.

Background

Several orthopaedic studies have found significant correlation between pre-operative psychological status and post-operative outcomes. The majority of research has focused on patients requiring lower limb and spine surgery. Few studies have investigated the effect of psychological status on the outcome of upper limb operations. We prospectively investigated the association between pre-operative psychological status and early postoperative shoulder pain and function in patients requiring arthroscopic subacromial decompression (ASAD) for impingement syndrome.

Introduction: The osteotomy in shoulder arthroplasty is based on the assumption that the resected articular segment corresponds to a segment of a sphere oriented, identically, in inclination and retroversion to the original humeral head(1). A previous report has suggested that the traditional osteotomy technique performed along the antero-superior part of the anatomical neck does not accurately replicate inclination and retroversion of the humeral head(2). We hypothesize that a simulated osteotomy performed along the antero-inferior anatomical neck resects a portion of the humeral head similarly oriented to the original head in terms of inclination and retroversion, and, more closely matches head diameter and radius of curvature when compared to the traditional osteotomy approach.

Methods: Twenty-eight fresh frozen cadaveric full arms were dissected free of soft tissue. Lines, points and surfaces were identified on each specimen. A Microscribe digitizer was used to digitize the points and lines. Data were imported into Rhinoceros NURBS modelling software and graphically modelled. The following parameters were used to describe the humeral head geometry: the longitudinal and axial radii of curvature (RoC) of the articular surface; the inclination angle (ƒÑ) and retroversion angle (ƒÒ). To simulate the traditional osteotomy, a plane was constructed using points at the anterior portion of the anatomical neck. The new osteotomy plane was formed using points at the antero-inferior anatomical neck. Paired Student’s t-test was used to compare techniques.

Results: No differences were found between the axial RoC of the resected segment for the new technique (22.5mm) when compared to the original head (22.5mm); a difference was found for the old osteotomy technique (23.0mm). In the coronal plane, no differences were found for the RoC of both the new and traditional techniques when compared to the original head. The axial and coronal diameters of the osteotomized surface were significantly different for both techniques. However, the mean difference between the axial and coronal diameters for the new technique was 2.4mm and, for the traditional technique, 3.2mm. Significant differences in retroversion of the resected surface were found when the new osteotomy technique (24.5deg) and traditional technique (40.5deg) were compared to the original head (29.0deg). Further, significant differences in inclination were found, when the new osteotomy technique (129.5deg) and traditional technique (132.1deg) were compared to the original head inclination (136.9deg).

Discussion: This study found that an osteotomy performed along the anteroinferior part of the anatomical neck removes an articular segment that is more spherical than a segment removed by the traditional osteotomy approach. Although significantly different from the original head, the retroversion associated with the new technique more closely matches the anatomy when compared to the traditional technique. The new osteotomy decreased the inclination angle by 7 degrees. This finding is unlikely to be clinically relevant. Cadaveric studies will reveal the accuracy of an anatomical reconstruction using the novel osteotomy approach.

Introduction: Successful shoulder arthroplasty is based on restoration of the individual’s proximal humeral morphology with a precise osteotomy of the humeral head at the level of the anatomical neck. The objective of this study was to determine the geometry of the articular portion of the humeral head in contact with the glenoid in the neutral position and compare the orientation to the geometry of the humeral head determined using the cartilage/calcar interface of the anatomical neck.

Methods: An intact rotator cuff and joint capsule were exposed for six cadaveric full arms. Precision perspex reference cubes were attached to the greater tuberosity of the humerus and to the coracoid process of the scapula on each specimen. Each shoulder was mounted in a custom built jig with the arm fixed in the neutral position and a Microscribe 3D-X digitizer used to digitize three faces of each precision cube. The shoulder joint was then disarticulated and both the humerus and scapula re-mounted on the same jig, independently. The cube faces were re-digitized and relevant points, lines and surfaces were identified and digitized on each humerus and scapula. The humeri were then scanned using a high precision surface laser scanner.

The data collected from both digitizing tools were merged into the same coordinate system and graphically represented. Paired Student’s t-tests were used to compare the inclination and retroversion angles for the two techniques.

Results and discussion: The study found a significant difference in inclination (p less than 0.02) and no difference in retroversion (p equal to 0.75) when the glenoid position was used to calculate humeral head orientation (Inclination: Mean 11.5 deg., StD. 11.2 deg.; Retroversion: Mean 20.5 deg., StD. 6.6 deg.) when compared to using the cartilage/calcar interface (Inclination: Mean 134.1 deg., StD. 1.9 deg.; Retroversion Mean 21.7 deg., StD. 13.9 deg.).

Small deviations in the recovery of head orientation in shoulder arthroplasty may impact on the longevity of an implant. The differences in inclination and retroversion noted in this study may alter the load on the glenoid and/or rotator cuff mechanism in joint replacement. Further research is necessary.

Dynamic assessment of the wrist motion and the specific angles are difficult using the conventional methods. We wanted to adapt and assess the repeatability of the Fas-trak system for continuous monitoring of three dimensional (3 D) wrist movements.

Twenty seven volunteers, aged 18 to 30 years were asked to perform predetermined tasks. The exclusion criteria were previous history of wrist trauma or joint disease. The transmitter was mounted on the dorsum of the forearm while the sensor was placed over the third metacarpal head. The protocol of three tasks was developed. Task 1 measured maximal flexion, extension, radial and ulnar deviation of the wrist. Task 2 involved picking up an object and moving it across a barrier. Task 3 involved the writing simulation. The comparison between the left and the right wrists indicated suitability of the system to be used on either of the limbs. Repeated measurements on the right wrist provided an assessment of repeatability of the Fastrak system.

The Fastrak system was successful in acquiring data in 3 D. The transmitter and the sensor were easy to attach and were of no discomfort to the subjects. As expected the maximum movement was noted in the flexion-extension plane. The total arc of movement in the flexion-extension plane was 127.1 degrees and 69.7 degrees in the radio-ulnar plane. There was no statistically signifi-cant difference between the movements in the left and the right wrists, even when the effect of dominance was considered. The lift and move task showed that most subjects utilised three-fourths of the total possible radio-ulnar movement, but only one-thirds of the total flexion and extension. The writing simulation revealed a substantial variability between subjects. The Fastrak system revealed variation up to 3 degrees in the means of range of movements, while measuring wrist movements.

The current study showed that the Fastrak system is a user-friendly and repeatable device, which could be used in everyday clinical use. It has the potential to be used for evaluation of the diseased wrist and the results of therapeutic interventions, operative or otherwise.

The present study investigates the repeatability of two new methods of measuring acetabular wear with differing levels of automation. Experimental evaluation showed that the more automated method was more repeatable. Both methods segmented the femoral head and acetabular rim with ellipses. The displacement of the ellipse centres was measured and the difference at year 1 and 5 taken as a measure of wear. Measurements were obtained twice for each case. The less automated of the two methods involved the annotation of 9 points on the femoral head and 18 on the acetabular rim to which two least squares ellipse fits[1] were performed. The second and more automated method was active ellipses[2][3]. This method uses iterative robust ellipse fitting and a model of appearance learned from a training set to cause two ellipses to converge on the contours of the femoral head and acetabular rim from a single starting point. Fifty cases with radiographs taken at year 1 and year 5 were measured by both methods. The radiographs contained CPTs with 28mm heads and were digitized at 150 dpi. Fifty postoperative radiographs containing 22.225mm Zimmer CPT heads trained the more automated method. None of the radiographs had metal backed cups or highly eccentric rims. The repeatability coefficient (2 standard deviations) of the active ellipses was 0.23mm and that of the best annotator was 0.40mm while the worst was 2.69mm due to an outlying measurement. Limits of agreement were calculated between the two methods as −0.61mm to 0.91mm and show the active ellipses could replace annotation. Given that the active ellipses are nearly twice as repeatable this is desirable. The range of difference in measurements for the active ellipses is less than that of the annotator.

Introduction: Accurate recovery of humeral head geometry in shoulder arthroplasty is an important requirement for a good functional outcome. Despite this, spherical prosthetic components are implanted when the total proximal humerus is described as ovoid¹. However, 60 to 80 % of the head is spherical¹. If, in the normal glenohumeral joint, only the spherical portion is in contact with the glenoid then recovery of normal mechanics is likely with a spherical prosthetic component.

Contact patterns have been examined ex vivo² under static conditions but do not reflect the likely in vivo contact pattern under dynamic loading and have not been correlated to changes in sphericity of the articular surface. A recent study of the distal femur found that thickness of normal articular cartilage is positively correlated with loading³ and, thus, contact.

The objective of this study was to determine the feasibility of using a surface laser scanner to determine cartilage thickness and, therefore, likely contact area and to correlate changes in thickness to changes in sphericity of the articular surface.

Methods: A cadaveric arm without bony deformity or evidence of rotator cuff disease was dissected free of soft tissue and mounted on a rigid block within the frame of a surface laser scanner (Kestrel3D Ltd., UK). The articular surface of the humerus was scanned at a resolution of 200 μm. The cartilage was then dissolved away and the humerus re-scanned. The x,y,z coordinate data of the re-scanned bone were used to match the sub-chondral bone with the cartilage from the previous scan using Pointstream™ software (Kestrel3D Ltd., UK).

The cloud point data for the cartilage and bony surfaces were exported into modelling software (McNeal and Assoc., Seattle, WA) and the surface area of the head divided into ten equal sections. For each slice of both the cartilage and bony surface, the radius of curvature was calculated using a least square fit optimisation technique⁴. The differences in radius of curvature between the cartilage surface and subchondral bone surface were used to calculate the cartilage thickness for each slice. The standard deviation from the radius of curvature was used to calculate the degree of deviation from sphericity.

Results: For the first 60 % of the surface area, the deviation from sphericity was 0.5% of the radius with a cartilage thickness of 0.74 mm. The deviation from sphericity and cartilage thickness for 100% of the articular surface was > 1% and 0.63 mm, respectively.

Conclusions: The experiment proved that the surface laser scanner can be used to elucidate the relationship between contact patterns and articular curvature of the proximal humerus. The changes in sphericity concur with results from previous studies¹. Assuming cartilage thickness correlates to contact patterns at the normal glenohumeral joint, the change in cartilage thickness suggests that contact may occur only at the spherical portion of the head. Knowledge of this relationship may aid in future prosthetic design considerations or in modification of the osteotomy technique. To further support these findings, a 50μm laser scanner is being developed and will be used on a larger sample size.

Introduction: Restoration of original humeral head geometry in shoulder arthroplasty is a necessary requirement and may have a bearing on the longevity of the implant. Modern, adaptable, prosthetic components are believed to allow restoration of the individual’s proximal humeral anatomy, provided a precise osteotomy of the humeral head at the level of the anatomical neck is performed. The osteotomy and reconstruction of the humeral head is based on the assumption that the resected articular segment corresponds to a segment of a sphere oriented, identically, in inclination and retroversion to the original humeral head. Resection, along the mid-anterior portion of the cartilage/calcar border, is understood to create a surface that enables a prosthetic component to be mounted, retroverted and inclinated to the same degree as the original head geometry. The objective of this study was to determine the degree of variation in humeral head retroversion relative to the superior and inferior borders of the proximal humeral articular surface.

Methods: Twenty-eight fresh frozen human cadaveric full arms were dissected free of soft tissue to expose the proximal humerus. The distal end of the humeral shaft was potted in PMMA and fixed rigidly in a custom–built jig. The following points and lines were identified and marked on each specimen:

the circumference of the anatomical neck;

A Microscribe 3D-X digitizer was used to digitize the points and lines. The data for each humerus were imported into Rhinoceros NURBS modelling software and graphically represented. The constructed graphical model was used to divide the articular portion of the humeral head into six equal sections in the axial plane. The retroversion angle, relative to the epicondyles, was calculated for each section.

Results: A linear decrease in retroversion angle was noted from the most superior to most inferior point on the proximal humeral articular surface. The retroversion angle was greatest at the level of the insertion of the supraspinatus tendon (34.2deg +/−13.7deg) and least at the inferior cartilage/calcar interface (24.3deg +/−10.2deg).

Discussion: Accurate recovery of humeral head geometry is a requirement in order to achieve good function. The variability in retroversion, as it relates to its point of measurement, may effect the accuracy of pre-operative assessment of a patient’s humeral head geometry as well as the osteotomy during shoulder arthroplasty, and, thus, may impact on joint range of motion and stability post-operatively. Further investigation is warranted.

Introduction: The current study investigates the influence of the interosseous portion of the scapholunate and the radioscaphocapitate ligaments in the range of movement of the scaphoid and lunate during flexion and extension of the wrist.

Material and Methods: 10 embalmed cadaveric specimens were studied. A jig was designed to clamp the forearms, holding the wrist in a fixed angle. Metal pointers with 1.5mm diameter were inserted into the scaphoid and the lunate. Digital cameras were aligned from the posterior and radial views and sequential photographs obtained during the full range of motion of the specimens. The SL and the RSC ligaments were then sectioned with new series of photographs obtained between each step. The angles in the photographs were measured with specific software.

Results: Sectioning the SL increased the angle between the lunate and the scaphoid by 12° on average, while sectioning the RSC increased the SL angle by a further 2 ° with the wrist in maximal flexion. With the wrist in extension the angle was also increased by 12° after division of the SL and a further 2° after section of the RSC.

Conclusions: Although volar and dorsal inuries may be associated, our study suggests that the SL has a much greater influence on the relative movement of the scaphoid and lunate than the RSC. The method also suggests that in a number of cases the variation in agulation may be small enough not to be detected as significant on x-rays.

Introduction – Electronic storage of X-rays is becoming standard. It would therefore, be highly desirable to use a computer as a tool for obtaining useful measurements from radiographs. The current study investigates the reliability of computerised measurements of radiographs of the Souter-Strathclyde elbow.

Materials and Methods – 56 AP radiographs of Souter-Strathclyde Elbows were assessed for the parameters described by Trail et al (1999). The respective x-rays were digitised using a transparency flatbed scanner with a resolution of 80 ï m/pixel. The radiographs were then measured for the migration and movement of the prosthesis using the following lines: Hapd1, Hapd2, Hapd3 Hapd4. All the radiographs were measured twice manually with at least one week interval, the observer being blind to the initial results at the time of the second measurement. The x-rays were again measured twice using the computer and a measuring software developed in our own department. The results were analysed for intra observer variability, using paired t-test and Pearson correlations.

Results – Table 1 shows the results of the paired measurements, with the confidence intervals for the mean error, the p for the paired t-test and the correlations between the paired readings. M1 and M2 represent the manual readings, while C1 and C2 the computerised readings.

Conclusions – The mean error of all paired readings was below 1 mm. The correlation between all paired readings was highly significant, with all the paired readings with the computer as a tool being .99. The only difference that was statistically significant was Hapd3M1-M2, between two manual measurements, although the mean error is not clinically relevant, still being less than 1mm. We conclude that computerised measurements of radiographs are at least as reliable as those conducted directly on film.

Objectives: The current study evaluates the effectiveness of a direct access physiotherapy shoulder clinic, in terms of a faster treatment, levels of patient satisfaction and consultants workload relief.

Material and Methods: A protocol of management of shoulder Pain was created establishing the patients pathway from general practice to orthopaedic surgery. A clinical specialist physiotherapist was trained to lead a shoulder clinic. A course on injections taught by consultants was followed by a training period of 10 supervised injections. After this initial period, a letter was sent to all GPs in the area informing that patients could be referred direct to the physio-shoulder clinic. Patients coded for consultation were also re-directed to that clinic. Only patients who did not improve after the initial treatment or who presented more complicate screening problems were redirected through a short cut to the consultant led clinic. A patient satisfaction questionnaire was used during the first 5 months.

Results Over the first 2 years of the project, 203 patients were appointed to the open shoulder clinic. The first 60 patients were given the patient satisfaction questionnaire, with 47 returning it completed. 28 of the 47 had been seen by a physio before. In a satisfaction scale of 1 to 5, 2 graded 3, 3 graded 4 and 42 graded 5 the advice received about their condition. In a similar scale 2 patients rated 3, 2 rated 4 and 43 rated 5 regarding their satisfaction with the opportunity to discuss their treatment/care options. Regarding arrangements for further care, 1 rated 1, 2 rated 3, 6 rated 4 and 36 rated 5. For overall satisfaction 1 rated 2, 2 rated 3, 2 rated 4 and 42 rated 5. Positive aspects of patients feedback included ample time to ask questions, improvement obtained with early start of treatment and more accessible discussion. 47% of the patients attending were followed up by Physiotherapy only, 18% were added directly to the surgical waiting list and 4 were referred for rheumatology. 22% were sent for further tests such as MRI and USS. The waiting list for a first appointment in our upper-limb clinic was reduced from 46 weeks in 2001 to 36 weeks in 2003. Not a single patient insisted on seeing a consultant and 38% of the patients were discharged without specifically seeing one.

Conclusion This study shows that a physio screening shoulder clinic is an effective and satisfactory way to reduce waiting times and improve patient care.

Introduction: Osteoporosis is diagnosed by measurement of bone mineral density (BMD), with techniques that include single and dual energy x-ray absorptiometry (SXA, DXA) and quantitative computed tomography (QCT), which have relatively high cost and limited availability. Radiographic absorptiometry (RA), the corresponding technique based on plain radiographs, has not been favoured clinically because it required complex devices to calibrate and difficult techniques to measure the optic densitometry of films. In this paper a newly developed computerised radiographic technique is described that gives results in actual BMD units and includes a correction for soft-tissues. The technique has been developed in conjunction with a new solid phantom to facilitate the use in fracture clinics, without the need for further patient exposure. It also has the advantage of measuring the ultradistal radius, a clinically useful cancellous rich site. The design of the phantom and initial calibration testing are described.

M& M: The new phantom is constructed from a solid water equivalent material, removing the need for a soft-tissue equalising water bath. The necessary hydroxyapatite (HA) calibration wedge is built into the phantom to give results in actual BMD units. A high-density grid has been used to minimise the effects of scatter caused by soft tissues. The phantom was initially calibrated by comparing its results with those obtained from specially manufactured hydroxyapatite disks. The European Forearm Phantom (EFP) was used in studies of further calibration and testing of anatomical specimens, obtained with permission from the department of Anatomy at the University of St. Andrews.

Results: The test comparing the BMD determined by the new phantom to the known density of specially manufactured HA discs yielded a very high correlation (R> 0.999) with an error < 2%. Further studies with the EFP as a reference standard confirmed a very high correlation (R> 0.999) with an error of < 5%.

Finally a study was performed on 25 cadaver forearms that were available for imaging using DXA and the modified RA technique. BMD results showed good correlation (R=0.93, P< 0.001) with an error of less than 10%. The error is partly explained because during this part of the study a high-resolution anti-scatter grid was unavailable and a standard grid had to be used. Also some cadavers had previous fractures and dissection marks. Without these problems, it is expected that the error percentage would be significantly reduced.

Discussion: The phantom is light, small and the patient can comfortably fit even if the limb is fractured. The results compare favourably with published data for existing techniques that also used the EFP as a reference standard. The described technique carries the promise of a simple, inexpensive system, which yields superior results and can be used seamlessly in a fracture clinic. A pilot clinical study is being planned, comparing the results of the modified RA technique with peripheral DXA. This system can be quickly made available at minimum cost utilizing existing equipment. All the other advantages of computerised x-rays including more precise measurements of deformity and central analysis from a distance for isolated practices apply.