Purpose

Limited information is available regarding the functional outcomes of radial head fractures managed with open reduction and internal fixation (ORIF). The purpose of this study was to determine the functional outcomes of radial head fractures treated with ORIF.

Purpose

Radial head implant over-lengthening, a common cause of capitellar wear and clinical failure, is difficult to diagnose using radiographs of the injured elbow. The purpose of this study was to determine if a novel measurement technique based on contralateral elbow radiographs, termed the RACER method, could be used to accurately estimate the magnitude of radial head implant over-lengthening. Part I of this study examined the side-to-side consistency of radiographic landmarks used in the measurement technique. Part II of this study validated the technique using simulated radial head implant over-lengthening in a cadaveric model.

Purpose

There have been a number of described techniques for sizing the diameter of radial head implants. All of these techniques, however, are dependent on measurements of the excised native radial head. When accurate sizing is not possible due to extensive comminution or due to a previous radial head excision, it has been postulated that the proximal radioulnar joint (PRUJ) may be used as an intraoperative landmark for correct sizing. The purpose of this study was to: 1) determine if the PRUJ could be used as a reliable landmark for radial head implant diameter sizing when the native radial head in unavailable, and (2) determine the reliability of measurements of the excised radial head.

Purpose

Current coronoid fracture classification systems are based on fragment size and configuration using plain radiographs and/or CT. During surgery, coronoid fracture fragments appear much larger than anticipated because cartilage is radiolucent and therefore not taken into account with preoperative imaging. The purpose of this study was to quantify the articular cartilage thickness of the coronoid process, with reference to coronoid fracture classifications.

Purpose

The coronoid process is an integral component for elbow stability. In the setting of a comminuted coronoid fracture, where repair is not possible, a prosthetic device may be beneficial in restoring elbow stability. The hypothesis of this in-vitro biomechanical study was that an anatomic coronoid prosthesis would restore stability to the coronoid deficient elbow.

Purpose

Capitellum hemiarthroplasty is an emerging concept. The current metallic capitellar implants have spherical surface shapes, but the native capitellum is not spherical. This study evaluated the effect of capitellar implant shape on the contact mechanics of the radiocapitellar joint when articulating with the native radial head.

Purpose of the study

Release of tight lateral structures is an integral part of balancing the valgus knee during knee replacement surgery. The posterolateral capsule is released through an inside-out technique. The common peroneal nerve is in close proximity to the capsule during this step. This study was undertaken to determine the distance of the nerve and the safe level for the posterolateral release.

Rapid prototyping (RP), especially useful in surgical specialities involving critical three-dimensional relationships, has recently become cheaper to access both in terms of file processing and commercially available printing resources.

One potential problem has been the accuracy of models generated. We performed computed tomography on a cadaveric human patella followed by data conversion using open source software through to selective-laser-sintering of a polyamide model, to allow comparative morphometric measurements (bone v. model) using vernier calipers. Statistical testing was with Student's t-test.

No significant differences in the dimensional measurements could be demonstrated. These data provide us with optimism as to the accuracy of the technology, and the feasibility of using RP cheaply to generate appropriate models for operative rehearsal of intricate orthopaedic procedures.

Hip resurfacing arthroplasty is an established and effective intervention for osteoarthritis of the hip in the young active patient, relying on the principle of femoral bone-stock preservation. A recognised mode of failure is neck thinning leading to radiological evidence of neck collapse and clinical failure.

We report on a series of these slow-neck-failure patients and highlight the increased incidence of this phenomenon in post-menopausal female patients. This is a single operator, single implant series; 172 cases were identified from databases at our institution. 76 were female, mean (SD) age 52 (7) years. 96 were male, mean (SD) age 51(12) years. 15 (8.7%) patients required revision. 12 (80%) were female, 9 (75%) of these were due to slow neck failure. In the men one patient developed ALVAL requiring removal of his bilateral hip resurfacings, the other failure mode was early femoral neck failure. Mean time to failure was 6 months in men and 37 months in women. This difference in failure rates is also seen in the NJR figures.

This review confirms the relatively high incidence of premature failure in post-menopausal females. NICE guidance in 2003, currently under review, stated that resurfacing is indicated in male patients up to 65 and female patients up to 60. As a result of this study we are currently advising post-menopausal patients that this risk of early failure may make total hip replacement a preferable option to resurfacing arthroplasty.

Introduction

Osteonecrosis (ON) is a disease that ultimately results in bone collapse. We investigated the correlation between SNPs and osteonecrosis.

We carried out a prospective investigation into the radiological outcomes of uncemented Oxford medial compartment unicondylar replacement in 220 consecutive patients (231 knees) performed in a single centre with a minimum two-year follow-up. The functional outcomes using the mean Oxford knee score and the mean high-activity arthroplasty score were significantly improved over the pre-operative scores (p < 0.001). There were 196 patients with a two-year radiological examination performed under fluoroscopic guidance, aiming to provide images acceptable for analysis of the bone–implant interface. Of the six tibial zones examined on each knee on the anteroposterior radiograph, only three had a partial radiolucent line. All were in the medial aspect of the tibial base plate (zone 1) and all measured < 1 mm. All of these patients were asymptomatic. There were no radiolucent lines seen around the femoral component or on the lateral view. There was one revision for loosening at one year due to initial inadequate seating of the tibial component. These results confirm that the early uncemented Oxford medial unicompartmental compartmental knee replacements were reliable and the incidence of radiolucent lines was significantly decreased compared with the reported results of cemented versions of this implant. These independent results confirm those of the designing centre.

Introduction

Osteonecrosis (ON) is one of the most debilitating skeletal disorders. Most patients with ON of the femoral head eventually require surgery, usually total hip arthroplasty, within a few years of disease onset. Previous reports have shown that alendronate reduces osteoclastic activity and reduces the incidence of femoral head collapse in osteonecrotic hips. A randomized study to examine the ability of alendronate to delay or prevent femoral head collapse was performed.

Purpose: Techniques to quantify soft-tissue forces in the upper extremity are not well described. Consequently, ligament forces of the elbow joint have not been reported. Knowledge of the magnitudes of tension of the primary valgus stabilizer, the anterior bundle of the medial collateral ligament (AMCL), would allow for an improved understanding of the load bourne by the ligament. The purpose of this in vitro study was to quantify the magnitude of tension in the native AMCL throughout flexion with the arm in the valgus orientation. We hypothesized that tension in the AMCL would increase with flexion.

Method: Five fresh-frozen cadaveric upper extremities (mean age 72 ± 10 years) were tested. To produce active muscle loading in a motion simulator, cables were affixed to the distal tendons of the brachialis, biceps brachii, triceps brachii, and brachioradialis and attached to actuators. The wrist was fixed in neutral flexion/extension and the forearm in neutral rotation. The arm was orientated in the valgus gravity-loaded position. A custom designed ligament load transducer was inserted into the AMCL. Active simulated flexion was achieved via computer-controlled actuation while passive elbow flexion was achieved by an investigator manually guiding the arm through flexion. Motion of the ulna relative to the humerus was measured using a tracking device.

Results: Both the active and passive motion pathways showed an increase in AMCL tension with increasing angles of elbow flexion (p < 0.05). There was no difference in AMCL tension levels between active and passive elbow flexion (p = 0.20). The mean maximum tension achieved was 97±33N and 94±40 N for active and passive testing respectively.

Conclusion: AMCL tension levels were observed to increase with elbow flexion, indicating that other structures (such as the joint capsule and the shape of the articulation) are likely more responsible for joint stability near full extension, and that the AMCL is recruited at increased angles of elbow flexion. With respect to load magnitudes, Regan et al. found the maximum load to failure of the AMCL was 261 N, while Armstrong et al. reported a failure load of 143 N in cyclic testing. The maximum AMCL tension level observed in this study was 160 N. Failure of the AMCL was not observed, which may be due to differences in specimen size, age, or the method of load application. In summary, this in vitro cadaveric study has provided a new understanding of the magnitudes of AMCL tension through the arc of elbow flexion, and this has important implications with respect to the desired target strength of repair and reconstruction techniques. These findings will also assist in the development and validation of computational models of the elbow.

Purpose: Most displaced olecranon fractures can be treated with ORIF. However with severe comminution or bone loss, excision of the fragments and repair of the triceps to the ulna is recommended. The triceps can be reattached to either the anterior or posterior aspect of the ulna. The purpose of this in-vitro study was to determine the effect of triceps repair technique on elbow laxity and extension strength in the setting of olecranon deficiency.

Method: Eight unpreserved cadaveric arms were used (age 75 ± 11 years). Surface models were generated from CT images and sequential olecranon resections in 25% increments were performed using real-time navigation. Muscle tendons (biceps, brachialis, brachioradialis and triceps) were sutured to actuators of an elbow motion simulator, which produced active extension. A tracking system recorded kinematics in the varus and valgus positions. A triceps advancement was performed using either an anterior or posterior repair to the remaining olecranon in random order. Triceps extension strength was measured in the dependent position with the elbow flexed 90° using a force transducer located at the distal ulnar styloid, while triceps tension was increased from 25–200 N. Outcome variables included maximum varus-valgus elbow laxity and triceps extension strength. Two-way repeated measures ANOVAs were performed for laxity comparing resection level and repair method. Three-way repeated measures ANOVAs were performed for triceps extension strength comparing triceps tension, resection level and repair method. Significance was set at p < 0.05.

Results: Progressive olecranon resection increased elbow laxity (p < 0.001). Although the posterior repair produced slightly greater laxity for all but the 50% resection, this difference was not significant (p = 0.2). The posterior repair provided greater extension strength than the anterior repair at all applied triceps tensions and for all olecranon resections (p = 0.01). The initial 0% resection reduced extension strength for both repairs (p < 0.01), however, there was no effect of progressive olecranon resections (p = 0.09).

Conclusion: There was no significant difference in laxity between the anterior and posterior repairs. Thus even for large olecranon resections, the technique of triceps repair does not have significant influence on joint stability. Extension strength was not reduced by progressive olecranon resections, perhaps due to wrapping of the triceps tendon around the trochlea putting it in-line with the ulna and giving it a constant moment arm. Triceps extension strength was higher for the posterior repair. This is likely due to the greater distance and hence moment arm of the posterior repair to the joint rotation center. Conversely, the anterior repair brings the triceps insertion closer to the joint center, reducing the moment arm. Since there was no significant difference in laxity between the repairs, the authors favour the posterior repair due to its significantly higher triceps extension strength.

Purpose: This in-vitro study examined the effect of simulated Colles fractures on load transmitted to the distal ulna, using an in-line load cell. Our hypothesis was distal radial fracture malposition will increase distal radial ulnar joint (DRUJ) load relative to the native position of the radius.

Method: Eight fresh frozen upper-extremities were mounted in a motion simulator which enabled active forearm rotation. An osteotomy was performed just proximal to the distal radioulnar joint, and a 3-degree of freedom modular appliance was implanted which simulated Colles type distal radial fracture deformities. This device allowed for accurate adjustment of dorsal angulation and translation (0, 10, 20 and 30 degrees dorsal angulation and 0, 5 and 10mm dorsal translation both isolated and in combination). A 6-DOF load cell was inserted in the distal ulna 1.5 cm proximal to the ulnar head to quantify DRUJ joint forces. Distal ulnar loading was measured following simulated distal radial deformities with both an intact and sectioned triangular fibrocartilage complex (TFCC).

Results: The maximum resultant transverse distal ulnar load occurred during active forearm pronation and supination. Increasing magnitudes of dorsal angulation and translation of the distal radius increased loading in the distal ulna. For pronation with the ligaments intact, the transverse resultant load for the non-fracture, native positioning was significantly lower (p< 0.05) than the majority of malpositioned cases except for the translations only (not combined with angulation). However, all fracture orientations for supination had an increased effect on the resultant loading (p< 0.05) when ligaments were intact. Greater forces were measured in the distal ulna when the TFCC intact relative to TFCC sectioning. Sectioning the TFCC eliminated the effect of fracture malposition for both pronation and supination. The range of maximum transverse force for intact pronation and supination was between 118& #61617;34N and 130& #61617;39N, respectively. Similarly, for sectioned pronation and supination, the maximum transverse forces were and 93& #61617;40N and 89& #61617;24N, respectively.

Conclusion: Malpositioning of distal radial fractures in dorsal translation and angulation was found to increase forces in the distal ulna, which may be an important source of residual pain following malunion of Colles fractures. Healing of the distal radius in an anatomic position resulted in the least forces. Sectioning the TFCC released the tethering effect of the radius on the ulna, decreasing DRUJ force. This is the first study of its kind to attempt to quantify the forces at the DRUJ as a result of Colles fractures, and these early findings provide important baseline information related to the biomechanics of the DRUJ.

Purpose: The identification of anatomical landmarks is an important aspect of joint surgery, to ensure proper placement and alignment for implants and other reconstructive procedures. At the elbow, the center of the capitellum (derived via a digitization of the surface and subsequent sphere fitting) has been well established as a key landmark to identify the axis of rotation of the joint. For some cases, and in particular minimally invasive surgery, only small regions of the capitellum may be exposed which may lead to errors in determining the centre. The purpose of this study was to identify the optimal location of digitizations of the capitellum.

Method: Twenty-five fresh frozen cadaveric distal humeri (19 left, 6 right) were studied. Using an x-ray computed tomography scanner, volumetric images of each specimen were acquired and used to reconstruct a 3-dimensional digital model of the specimen using the Visualization Toolkit (VTK). A sphere-fit algorithm was used to determine the centre of the spherical capitellum based on manually chosen (digitized) points across the 3D capitellar surface. The true geometric centre was located by digitizing points across the entire capitellar surface. Three sub-regions of the capitellum, commensurate with typical surgical approaches with minimal dissection, were then digitized. These were superior anterior lateral (SAL), inferior anterior lateral (IAL) and a combination of these two regions. These regions were compared to the true center using a 1-way Repeated Measures ANOVA with significance set to p = 0.05.

Results: Digitizations of only SAL and IAL sub-regions resulted in the largest differences relative to the true centre: SAL = 3.9±3.4 mm, IAL = 4.2±3.4 mm, (p < 0.0005). There was no difference between SAL and IAL (p = 1.0). Digitization of the combined SAL + IAL regions, while significantly different from the entire capitellum, resulted in the smallest mean difference of 0.87±0.84 mm.

Conclusion: These data show that the region of digitization affects the accuracy of predicting the capitellum centre. In a previous study by our group, we showed that an accurate determination of the centre of a sphere can be achieved with a small surface area of digitization. In the current study, the large errors that occurred when a small surface was digitized (i.e. SAL and IAL alone), are in all likelihood, due the non-spherical nature of the capitellum. In summary, while the most precise method in locating the true centre is to digitize the entire capitellar surface where possible, an alternative approach is to digitize both the superior and inferior anterior lateral regions.

Controversy surrounds the most appropriate treatment method for patients with a rupture of the tendo Achillis. The aim of this study was to assess the long term rate of re-rupture following management with a non-operative functional protocol.

We report the outcome of 945 consecutive patients (949 tendons) diagnosed with a rupture of the tendo Achillis managed between 1996 and 2008. There were 255 female and 690 male patients with a mean age of 48.97 years (12 to 86). Delayed presentation was defined as establishing the diagnosis and commencing treatment more than two weeks after injury. The overall rate of re-rupture was 2.8% (27 re-ruptures), with a rate of 2.9% (25 re-ruptures) for those with an acute presentation and 2.7% (two re-ruptures) for those with delayed presentation.

This study of non-operative functional management of rupture of the tendo Achillis is the largest of its kind in the literature. Our rates of re-rupture are similar to, or better than, those published for operative treatment. We recommend our regime for patients of all ages and sporting demands, but it is essential that they adhere to the protocol.

Purpose: The purpose of this study was to determine the effect of serial olecranon resections on elbow stability.

Method: Eight fresh, previously frozen cadaveric arms underwent CT scanning. The specimens were mounted in an in-vitro motion simulator, and kinematic data was obtained using an electromagnetic tracking system. Simulated active and passive flexion was produced with servo-motors and pneumatic pistons attached to specific muscles. Flexion was studied in the dependent, horizontal, varus, and valgus positions. Custom computer navigation software was utilized to guide serial resection of the olecranon in 12.5% increments. A triceps advancement repair was performed following each resection.

Results: Serial olecranon resections resulted in a significant increase in valgus-varus (V-V) laxity for both passive (p< 0.001) and active (p=0.04) flexion. For passive motion this increase reached statistical significance following the 12.5% resection. This corresponded to an increase in V-V laxity of 1.4 ± 0.1o and a total laxity of 7.5 ± 1.0o. For active flexion this increase reached significance following the 62.5% resection. This corresponded to an increase in V-V laxity of 5.6 ± 1.1o and a total laxity of 11.2 ± 1.5. There was no significant effect of sequential olecranon excision on elbow kinematics or stability with the elbow in the vertical or horizontal positions. The elbows became grossly unstable after resection of greater than 75% of the olecranon.

Conclusion: A progressive increase in the varus-valgus laxity of the elbow was seen with sequential excision of the olecranon. Laxity of the elbow was increased with excision of 75% of the olecranon, likely due to the loss of the bony congruity and attachment site of the posterior band of the medial collateral ligament. Gross instability resulted when 87.5% or greater was removed, likely due to damage to the anterior band of the medial collateral ligament as it inserts on the sublime tubercle of the ulna. Rehabilitation of the elbow with the arm in the dependant position should be considered following excision of the olecranon; varus and valgus orientations should be avoided. The contribution of the olecranon to elbow stability may be even more important in patients with associated ligament injuries or fractures of the elbow.

Purpose: The role of the posterior bundle of the medial collateral ligament (PMCL) in stability of the elbow remains poorly defined. The purpose of this study was to determine the effect of sectioning the PMCL on the stability of the elbow.

Method: Varus and valgus gravity-loaded passive elbow motion and simulated active vertical elbow motion were performed on 11 cadaveric arms. An in-vitro elbow motion simulator, utilizing computer-controlled pneumatic actuators and servo-motors sutured to tendons, was used to simulate active elbow flexion. Varus/valgus angle and internal/external rotation of the ulna with respect to the humerus were recorded using an electromagnetic tracking system. Testing was performed on the intact elbow and following sectioning of the PMCL.

Results: With active flexion in the vertical position the varus/valgus kinematics were unchanged after PMCL sectioning (p=0.08). However, with the forearm in pronation, there was a significant increase in internal rotation after PMCL sectioning compared to the intact elbow (p< 0.05) which was most evident at 0° and 120° degrees of flexion (p< 0.05). This rotational difference was not statistically significant with the forearm in supination (p=0.07). During supinated passive flexion in the varus position, PMCL sectioning resulted in increased varus angulation at all flexion angles (p< 0.05). In pronation varus angulation was only increased at 120° of flexion (p< 0.05). However, internal rotation was increased at flexion angles of 30° to 120° (p< 0.05). In supination, sectioning the PMCL had no significant effect on maximum varus-valgus laxity or maximum internal rotation (p=0.1). However, in pronation, the maximum varus-valgus laxity increased by 3.5° (30%) and maximum internal rotation increased by 1.0° (29%) (p< 0.05).

Conclusion: These results indicate that isolated sectioning of the PMCL causes a small increase in varus angulation and internal rotation during both passive varus and active vertical flexion. This study suggests that isolated sectioning of the PMCL may not be completely benign and may contribute to varus and rotation instability of the elbow. In patients with insufficiency of the PMCL appropriate rehabilitation protocols (avoiding forearm pronation and shoulder abduction) should be followed when other injuries permit.

Purpose: Osteochondritis dissecans (OCD) of the capitellum most commonly affects adolescent pitchers and gymnasts, and presents with pain and mechanical symptoms. Fragment excision is the most commonly employed surgical treatment; however, patients with larger lesions have been reported to have poorer outcomes. It’s not clear whether this is due to increased contact pressures on the surrounding articular surface, or if fragment excision causes instability of the elbow. The purpose of this study was to determine if fragment excision of simulated OCD lesions of the capitellum alters kinematics and stability of the elbow.

Method: Nine fresh-frozen cadaveric arms were mounted in an upper extremity joint motion simulator, with cables attaching the tendons of the major muscle tendons to motors and pneumatic actuators. Electromagnetic receivers attached to the radius and ulna enabled quantification of the kinematics of both bones with respect to the humerus. Three-dimensional CT scans were used to plan lesions of 12.5% (mean 0.8cm2), 25%, 37.5%, 50%, and 100% (mean 6.2cm2) of the capitellar surface, which were marked on the capitellum using navigation. Lesions were created by burring through cartilage and subchondral bone. The arms were subjected to active and passive flexion in both the vertical and valgus-loaded positions, and passive forearm rotation in the vertical position.

Results: No significant differences in varus-valgus or rotational ulnohumeral kinematics were found between any of the simulated OCD lesions and the elbows with an intact articulation with active and passive flexion, regardless of forearm rotation and the orientation of the arm (p> 0.7). Radiocapitellar kinematics were not significantly affected during passive forearm rotation with the arm in the vertical position (p=0.07–0.6).

Conclusion: In this in-vitro biomechanical study even large simulated OCD lesions of the capitellum did not alter the kinematics or laxity of the elbow at either the radiocapitellar or ulnohumeral joints. These data suggest that excision of capitellar fragments not amenable to fixation can be considered without altering elbow kinematics or decreasing stability. Further study is required to examine other factors, such as altered contact stresses on the remaining articulation, that are thought to contribute to poorer outcomes in patients with larger lesions.

Purpose: This study evaluated the accuracy of humeral component alignment in total elbow arthroplasty. An image-based navigated approach was compared against a conventional non-navigated technique. We hypothesized that an image-based navigation system would improve humeral component positioning, with navigational errors less than or approaching 2.0mm and 2.0°.

Method: Eleven cadaveric distal humeri were imaged using a CT scanner, from which 3D surface models were reconstructed. Non-navigated humeral component implantation was based on a visual estimation of the flexion-extension (FE) axis on the medial and lateral aspects of the distal humerus, followed by standard instrumentation and positioning of a commercial prosthesis by an experienced surgeon. Positioning was based on the estimated FE axis and surgeon judgment. The stem length was reduced by 75% to evaluate the navigation system independent of implant design constraints. For navigated alignment, the implant was aligned with the FE axis of the CT surface model, which was registered to landmarks of the physical humerus using the iterative closest point algorithm. Navigated implant positioning was based on aligning a 3D computer model calibrated to the implant with a 3D model registered to the distal humerus. Each alignment technique was repeated for a bone loss scenario where distal landmarks were not available for FE axis identification.

Results: Implant alignment error was significantly lower using navigation (P< 0.001). Navigated implant alignment error was 1.2±0.3 mm in translation and 1.3±0.3° in rotation for the intact scenario, and 1.1±0.5 mm and 2.0±1.3° for the bone loss scenario. Non-navigated alignment error was 3.1±1.3 mm and 5.0±3.8° for the intact scenario, and 3.0±1.6 mm and 12.2±3.3° for the bone loss scenario. Without navigation, 5 implants were aligned outside 5° for intact bone while 9 were aligned outside 10° for the bone loss scenario.

Conclusion: Image-based navigation improved the accuracy of humeral component placement to less than 2.0 mm and 2.0°. Further, outliers in implant positioning were reduced using image-based navigation, particularly in the presence of bone loss. Implant malalignment may well increase the likelihood of early implant wear, instability and loosening. It is likely that improved implant positioning will lead to fewer implant related complications and greater prosthesis longevity.

Results: Repeatability of creating motion-based JCS was less than 1 mm and 1° in all directions. The inter-specimen standard-deviations of position and orientation measurements were smaller for the motion-based than for the anatomy-based JCS in every direction and for every specimen (p< 0.006). The ulno-humeral varus angle and internal/external rotation kinematics of active flexion showed less inter-specimen variability when calculated using motion-based JCS (p< 0.05).

Purpose: While computer-assisted techniques can improve the alignment of the implant articulation with the native structure, stem abutment in the intramedullary canal may impede achievement of this alignment. In the current study, the effect of a fixed valgus (6 degree) stemmed humeral component on the alignment of navigated total elbow arthroplasty was investigated. Our hypothesis was that implantation of a humeral component with a reduced stem length would be more accurate than implantation of the humeral component with a standard length stem.

Method: Thirteen cadaveric distal humeri were imaged using a CT scanner, and a 3D surface model was reconstructed from each scan. Implantation was performed using two implant configurations. The first set was unmodified (Regular) while the second set was modified by reducing the length of the humeral stem to 25% of the original stem (Reduced). A surface model of the humeral component was aligned with the flexion-extension (FE) axis of the CT-based surface model, which was registered to the landmarks of the physical humerus using the iterative closest point algorithm. Navigated implant positioning was based on aligning a 3D computer model calibrated to the implant with a 3D model registered to the distal humerus.

Results: Implant alignment error was significantly lower for the Reduced implant, averaging 1.3±0.5 mm in translation and 1.2±0.4° in rotation, compared with 1.9±1.1 mm and 3.6±2.1° for the Regular implant. Abutment of the implant stem with the medullary canal of the humerus prevented optimal alignment of the Regular humeral component as only four of the 13 implantations were aligned to within 2.0° using navigation.

Conclusion: These results demonstrate that a humeral component with a fixed valgus angulation cannot be accurately positioned in a consistent fashion within the medullary canal of the distal humerus without sacrificing alignment of the FE axis due to stem abutment. Improved accuracy of implant placement can be achieved by introducing a family of humeral components, with three valgus angulations of 0°, 4° and 8°. Based on humeral morphology for these specimens, 12 of the 13 implants may be positioned to within 2° of the native FE axis using one of these 3 valgus angulations.

Purpose: Coronal shear fractures of the humerus include the Kocher-Lorenz fracture, an osteochondral fracture of the capitellar articular surface, the Hahn-Steinthal fracture, a substantial shear fragment, extension into the trochlea, and complete involvement of the capitellum and trochlea. If the fracture proves irreparable, it is not known what the impact of fragment excision would have on the biomechanics of the elbow. The purpose of this study was to examine the effect of the sequential loss of the capitellum and trochlea on the kinematics and stability of the elbow.

Method: Eight fresh-frozen cadaveric arms were mounted in an upper extremity joint testing system, with cables attaching the tendons of the major muscles to motors and pneumatic actuators. Electromagnetic receivers attached to the radius and ulna enabled quantification of the kinematics of both bones with respect to the humerus. The distal humeral articular surface was sequentially excised to replicate clinically relevant coronal shear fractures while leaving the collateral ligaments intact. Active flexion in both the vertical and valgus-loaded positions, and passive rotation in the vertical position was conducted for each excision.

Results: Excision of the capitellum had no effect on ulnohumeral stability or kinematics in both the vertical or valgus positions (p=1.0). Excision of the entire capitellum and trochlea led to significant valgus instability with the arm in the valgus position (p=0.01), while excision of the lateral trochlea led to increased valgus instability with pronated flexion in the valgus position (p=0.049). Progressive loss of the articular surface led to posterior, inferior, and medial displacement of the radial head with respect to the capitellum and increased external rotation of the ulna with respect to the humerus in the vertical position (p< 0.05).

Conclusion: Excision of the capitellum did not result in valgus or rotational instability, while excision of the trochlea resulted in multiplanar instability. The radial head displaced medially because it is constrained to the ulna by the annular ligament, and the ulna pivoted into valgus and external rotation on the residual trochlea and medial collateral ligament. In patients with coronal shear fractures, the trochlea must be reconstructed to prevent instability and the potential for secondary degenerative change.

We have investigated whether the use of laminar-flow theatres and space suits reduced the rate of revision for early deep infection after total hip (THR) and knee (TKR) replacement by reviewing the results of the New Zealand Joint Registry at ten years.

Of the 51 485 primary THRs and 36 826 primary TKRs analysed, laminar-flow theatres were used in 35.5% and space suits in 23.5%. For THR there was a significant increase in early infection in those procedures performed with the use of a space suit compared with those without (p < 0.0001), in those carried out in a laminar-flow theatre compared with a conventional theatre (p < 0.003) and in those undertaken in a laminar-flow theatre with a space suit (p < 0.001) when compared with conventional theatres without such a suit. The results were similar for TKR with the use of a space suit (p < 0.001), in laminar-flow theatres (p < 0.019) and when space suits were used in those theatres (p < 0.001). These findings were independent of age, disease and operating time and were unchanged when the surgeons and hospital were analysed individually.

The rate of revision for early deep infection has not been reduced by using laminar flow and space suits. Our results question the rationale for their increasing use in routine joint replacement, where the added cost to the health system seems to be unjustified.

Introduction: Intra-articular steroid injection has long been used to treat osteoarthritis of the knee and hip by orthopaedic surgeons, rheumatologists and general practitioners. Recent literature has shown conflicting results with regard to its safety. We aimed to investigate whether a relationship exists between preoperative intra-articular steroid injection and postoperative infection in total knee arthroplasty (TKA).

Patients and Methods: We reviewed the records of all patients having TKA between April 2005 and April 2007 in University Hospital Aintree, Liverpool. The operations were carried out by 6 consultants. Exclusion criteria for analysis were: previous knee infection, revision knee surgery, fracture around the knee, skin disorders, diabetes, blood transfusion, rheumatoid arthritis and immunosuppressive medication. Eligible patients were divided into two groups: group I had received intra-articular steroid injection (each subject receiving 1–3 (mean 1.6) injections between 1–12 (mean 5) months before TKA); group II had received no injection. Mean follow-up was 17 months.

Results: 425 patients had TKA, of which 361 met our criteria. 121 patients in group I and 240 patients in group II. No-one in group I developed acute infection. In group II, 7 patients developed acute infection (5 superficial and 2 deep) between 1 and 6 weeks (mean 3.7 weeks) post-operatively. There were no late infections. The difference in infection rate between groups I and II was not statistically significant (P=0.1, Fisher’s exact test).

Conclusion: We found no evidence that intra-articular steroid injection prior to TKA increased the incidence of postoperative infection.

A longer stay in the hospital after primary total hip replacement is consistent with an increased morbidity and slower recovery for patients. In addition, it is among the more costly aspects of a total joint replacement. A process, which reduces the length of stay following this procedure and synchronically maintains the high standards of safe care would certainly improve the clinical practice and provide financial benefits.

Our objective was to evaluate the efficiency of a holistic perioperative, accelerated recovery programme following this procedure and in particular to assess its impact in the shot term patient’s recovery, morbidity, complications, readmission rate and cost savings for the NHS.

Eighty-nine patients participated in our rapid recovery programme, which is a comprehensive approach to patient care, combining individual pre-operative patient education, pain management, infection control, continuous nursing and medical staff motivation as well as intensive physiotherapy in the ward and the community. Forty-eight male and 41 female patients with an average age of 69 (range-50 to 87) underwent a total hip replacement in an NHS District General Hospital. The average BMI was 28 (range-18 to 39) and the average ASA 2.3 (range-1 to 4). The procedure was performed by 3 different surgeons using the same operative standards. A standardised post-operative protocol was followed and the patients were discharged when they were medically fit and had achieved the ward physiotherapy requirements. They were then daily followed up by a community orthopaedic rehabilitation team in patient’s own environment as long as it was required.

The average length of stay was reduced from 7.8 days to 5. There was no increase in complications–or readmissions rate while there were significant cost savings. The waiting list for this surgery was reduced and the patient’s satisfaction was high.

The rapid recovery programme for primary total hip replacement surgeries has been proved to be an efficient method of reducing the length of stay in hospital and consequently the financial costs while it ensures the safe and effective peri-operative management of patients.

Introduction: Geometry of the proximal femur has been identified as a risk factors for hip fracture. It is also suggested that the geometry of the proximal femur can influence the fracture type.

Aims: To identify if proximal geometry and hip fractures are related in two different population groups. Scotland–Monklands General Hospital, Lanarkshire–and Australia -Flinders Medical Centre, Adelaide.

Methods: Retrospective comparison of length and width of the femoral necks in 200 hip fracture patients. 100 patients in the Australian group and 100 patients in the Scottish group were analysed. 50 intracapsular and 50 intertrochanteric fractures were included in each group. All measurements where made from standardised digital anteroposterior radiographs. We attempted to correlate the length and width of the femoral neck with the fracture type.

Results: The populations were matched for age and sex, with the majority of fractures sustained by women. The results for the both populations show that a patient sustaining an intracapsular fracture is more likely to have a longer femoral neck (mean 40.56mm; Scottish population, 39mm; Australian population) than one sustaining an intertrochanteric fracture (mean 31.70mm; Scottish population, 29mm; Australian population) [P < 0.0001]. The femoral neck was also narrower in the intracapsular group. This was significant in Scottish population (mean 38.56mm, P < 0.03), but not in the Australian population (mean 38.3mm, P = 0.067). We also found that men had longer, wider femoral necks (P < 0.0001) compared to the female group.

Discussion: We found that hip fracture pattern is linked to proximal femoral geometry. This relationship is statistically significant in both population groups. Anthropologically, as the human race evolves and people get taller, their femoral neck lengths are increasing. This could translate into a change in the number and type of hip fractures. Intracapsular fractures may predominate and this could have implications on both treatment outcomes and resources for hip fracture patients.

We reviewed the rate of revision of unicompartmental knee replacements (UKR) from the New Zealand Joint Registry between 1999 and 2008. There were 4284 UKRs, of which 236 required revision, 205 to a total knee replacement (U2T) and 31 to a further unicompartmental knee replacement (U2U). We used these data to establish whether the survival and functional outcome for revised UKRs were comparable with those of primary total knee replacement (TKR). The rate of revision for the U2T cohort was four times higher than that for a primary TKR (1.97 vs 0.48; p < 0.05). The mean Oxford Knee Score was also significantly worse in the U2T group than that of the primary TKR group (30.02 vs 37.16; p < 0.01). The rate of revision for conversion of a failed UKR to a further UKR (U2U cohort) was 13 times higher than that for a primary TKR.

The poor outcome of a UKR converted to a primary TKR compared with a primary TKR should contra-indicate the use of a UKR as a more conservative procedure in the younger patient.

We analysed data from the Oxford hip and knee questionnaires collected by the New Zealand Joint Registry at six months and five years after joint replacement, to determine if there was any relationship between the scores and the risk of early revision. Logistic regression of the six-month scores indicated that for every one-unit decrease in the Oxford score, the risk of revision within two years increased by 9.7% for total hip replacement (THR), 9.9% for total knee replacement (TKR) and 12.0% for unicompartmental knee replacement (UKR). Our findings showed that 70% of the revisions within two years for TKR and 67% for THR and UKR would have been captured by monitoring the lowest 22%, 28% and 28%, respectively, of the Oxford scores. When analysed using the Kalairajah classification a score of < 27 (poor) was associated with a risk of revision within two years of 7.6% for THR, 7.0% for TKR and 24.3% for UKR, compared with risks of 0.7%, 0.7% and 1.8%, respectively, for scores > 34 (good or excellent).

Our study confirms that the Oxford hip and knee scores at six months are useful predictors of early revision after THR and TKR and we recommend their use for the monitoring of the outcome and potential failure in these patients.

Purpose: The aim of this nonrandomised retrospective study was to compare the results of anterior plating with superior plating in acute mid-shaft clavicular fractures.

Method: From 2000–2005, 49 fresh midshaft clavicular fractures in adults with shortening of > 20mm on the radiographs were treated with reconstruction plates. The placement of the plate on the clavicular surface was based on the preference of the surgeon operating. Patients were discharged within a day or two of the operation depending on pain control and were allowed to mobilise their shoulder within pain limits. They were followed up at six weeks and 12 weeks post operation and were allowed to return to work by 12 weeks if there was clinical and radiological signs of union. There were 22 patients in the anterior and 27 in the superior group. The mean age in the anterior was 36.3 years and 37.6 in the superior group. Majority(65%) of the fractures were sustained following RTA.77% were involved on the dominant side in both groups. The percent of patients in light and heavy manual work were similar in both groups. Follow up varied from six months to 24 months. Functional outcome was analysed by the physiotherapist with Biodex machine using Constant score and patient satisfaction questionnaire.

Results: There was no significant difference in Constant scores (Anterior=89, Superior=86), patient satisfaction with operation, return to activity and occupation in either groups. There was a total of six implant removals out of which five were in the superior group due to prominent metalware. There were two implant failures between six to 12 weeks post operation, both of which were in the superior group which were replated anteriorly. There was no significant difference in the deep/superficial infection in either groups. Return to work and satisfaction with operation were similar in both groups.

Conclusion: In our study, the incidence of hardware failure and hardware removal was significantly higher in the superior group compared to anterior group. Necessity for hardware removal becomes low as the anteriorly placed plate is less prominent. Also the risk of injuring the important neurovascular structures is less while drilling holes from anterior to posterior compared to superior to inferior direction. Hence we recommend anterior plating of the clavicle as a better method compared to superior plating of the clavicle.

It is established good practice that joint replacements should have regular follow-up and for the past seven years at the North Hampshire Hospital a local joint register has been used for this purpose and we compare this with results of the Swedish and UK national registries.

Since March 1999, all primary and revision knee arthroplasties performed at North Hampshire Hospital, Basingstoke have been prospectively recorded onto a database set up by one of the senior authors (JMB). Data from patients entered in the first six years of the register were analysed. All patients have at least one year clinical and radiological review then a minimum of yearly postal follow-up.

As of 31/12/2006, 2854 knee replacement procedures had been performed under the care of 13 consultants. OA was the most common diagnosis in over 75% of knees. 5.2% of patients had died and 4.6% were lost to follow-up. Our revision burden was 3.5% and we had a revision rate of 1.4% for primary total knee replacements. Audit of data for revisions and patello-femoral replacements has enabled us to change our practices. Mean length of stay was 7.2 days for primary total knee arthroplasty versus 4.0 days for unicompartmental knee arthroplasty and 5.4 days for patellofemoral replacement and mean flexion at discharge was 88.4, 93.7 and 88.7 degrees respectively. WOMAC and Oxford scores at 2 years had improved from a mean of 52 and 21 pre-operatively to 74 and 39 respectively for primary total knee arthroplasty. Our costs are estimated at approximately £35 per patient for their lifetime on the register.

Compared to other registries:

Our dataset is more complete and comprehensive

Stress shielding (i.e. reduction in bone strains) in the distal ulna is commonly noted following ulnar head replacement arthroplasty. Optimal design parameters for distal ulnar implants, including the length of the stem, are currently unknown. The purpose of this study was to investigate the effect of stem length on bone strains along the length of the ulna.

Strain gauges were applied to each of eight cadaveric ulnae to measure bending loads at six locations along each ulna’s length (approximately 1.5, 2.5, 4.0, 6.0, 8.0, and 13.0cm from the ulnar head). The proximal portion of each bone was secured in a custom-designed jig. A materials testing machine applied loads (5–30N) to the ulnar head while native strains were recorded. The ulnar head was removed and the loading procedure repeated for cemented stainless steel stems 3 and 7cm in length, according to a previously reported technique (Austman et al, CORS 2006). Other stem lengths between 3 and 7cm were tested in 0.5cm intervals with a 20N load applied only. Data were analyzed using a two-way repeated measures ANOVA (á=0.05).

In general, distal bone strains increased as stem length decreased (e.g. average microstrains at the second distal-most gauges: 138±13 (7cm), 147±15 (6cm), 159±21 (5cm), 186±40 (4cm), 235±43 (3cm)). The native strains were different from all stem lengths for the four distal-most gauges (p< 0.05). No differences were found between any stem length and the native bone at the two proximal-most gauges. The 3cm stem replicated the native strains more closely than the 7cm, over all applied loads (e.g. average microstrains at the third gauge level for a 25N load: 357±59 (native), 396±74 (3cm), 257±34 (7cm)).

No stem length tested matched the native strains at all gauge locations. The 3cm stem results were closer to the native strains than the 7cm stem for all loads at gauges overtop of the stem. Overall, the 3cm stem produced the highest strains, and thus would likely result in less distal ulnar bone resorption after implantation. These results suggest that shorter (approximately 3cm) stems should be considered for distal ulnar implants to potentially reduce stress shielding, although this must be balanced by adequate stem length for fixation.

We have reviewed the rate of revision of fully cemented, hybrid and uncemented primary total hip replacements (THRs) registered in the New Zealand Joint Registry between 1999 and December 2006 to determine whether there was any statistically significant difference in the early survival and reason for revision in these different types of fixation. The percentage rate of revision was calculated per 100 component years and compared with the reason for revision, the type of fixation and the age of the patients.

Of the 42 665 primary THRs registered, 920 (2.16%) underwent revision requiring change of at least one component. Fully-cemented THRs had a lower rate of revision when considering all causes for failure (p < 0.001), but below the age of 65 years uncemented THRs had a lower rate (p < 0.01). The rate of revision of the acetabular component for aseptic loosening was less in the uncemented and hybrid groups compared with that in the fully cemented group (p < 0.001), and the rate of revision of cemented and uncemented femoral components was similar, except in patients over 75 years of age in whom revision of cemented femoral components was significantly less frequent (p < 0.02). Revision for infection was more common in patients aged below 65 years and in cemented and hybrid THRs compared with cementless THRs (p < 0.001). Dislocation was the most common cause of revision for all types of fixation and was more frequent in both uncemented acetabular groups (p < 0.001). The experience of the surgeon did not affect the findings.

Although cemented THR had the lowest rate of revision for all causes in the short term (90 days), uncemented THR had the lowest rate of aseptic loosening in patients under 65 years of age and had rates comparable with international rates of aseptic loosening in those over 65 years.

Aim: The purpose of this study was to report the long-term follow-up (mean of 15 years) of patients with displaced intra-articular calcaneal fractures from a randomised controlled trial published in 1993.

Patients and Methods: 46 patients (82% of patients in the initial study group) were alive at a mean of 15 years post injury. The patients had been randomly allocated to either conservative or operative (Soeur and Remy technique) treatment in the original study. Clinical (AOFAS, FFI and calcaneal fracture score) and radiological (Böhler’s angle and calcaneum height) outcome measures were used. The grade of osteoarthritis was also assessed at long-term follow-up.

Results: 26 patients (57%) were reviewed and these patients served as the focus of the study (11 conservative and 15 operative). The clinical outcomes after conservative treatment were not found to be different from those after operative treatment, scores of the AOFAS were 78.5 and 70 respectively (p = 0.11); scores of the FFI were 24.4 and 26.9 respectively (p = 0.66) and calcaneal fracture scores were 70.1 and 63.5 respectively (p = 0.41). The radiological outcomes after conservative treatment were not found to be different from those after operative treatment, Böhler’s angles were 10° and 16° respectively (p = 0.07) and the height of the calcaneum were 37mm and 36mm respectively (p = 0.57). There was no difference in the grade of osteoarthritis between the groups.

Conclusion: The functional and radiological long-term outcomes after conservative treatment of displaced intra-articular calcaneal fractures were equivalent to those after operative treatment. The operative technique showed no benefit compared to conservative treatment at long-term follow-up. There was a trend for higher scores on clinical outcomes with conservative treatment

Aims: To determine the anthropometric measurements of bony landmarks in the knee using MR scans and so assist revision knee surgeons in prostheses placement.

Methods: We analysed 100 MR scans of patients aged 16–50 (50 male, 50 female) which were performed for meniscal pathology, patellar dislocation and ACL injury. Those over the age of 50 or with symptoms suggestive of general osteoarthritis, or where the epiphyses had not yet fused were excluded. All measurements recorded were to the level of joint line and are shown below.

Conclusions: To ensure near normal knee mechanics are achieved during revision knee surgery the joint line should be within 5mm of the original. Our study provides mean values for the distance from various bony landmarks to the joint line in non-arthritic knees on MR scan. The use of the medial epicondyle value as a sole reference will place the joint line within 5mm in 88% of males and 96% of females. Use of multiple landmarks further increases accuracy. The final position of the joint will depend on trialling prostheses.

Introduction: Serum inflammatory markers are routinely used as pre assessment investigation before the revision hip surgery. Various investigations are used to aid in diagnosis of infection in the revision prosthetic hip replacement including aspiration, broad range PCR, bone scan and serum interleukin- 6.

Materials and Methods: 256 consecutive revision total hip replacements were assessed for the value of pre operative ESR and c-reactive proteins (CRP) in predicting the deep infections.

All patients were evaluated prior to surgery. The patients with coexisting inflammatory disease or peri-prosthetic fracture were also evaluated.

A hip was diagnosed as infected on the basis of positive intra operative microbiology samples three or more out of five and or histological evidence.

Results: Using the values of ESR > 35 mm/1^st hour and CRP> 10mg/l, the positive predictive value (either /or) was 56% and the negative predictive value was 96%. 14 patients had an underlying inflammatory arthritis and 5 were peri prosthetic fractures. The inflammatory markers tended to be elevated in these patients. Excluding these 19 patients and using the same criteria, the positive predictive value was 65% and the negative predictive value was 97%

Discussion: We conclude that a CRP< 10 mg/l and ESR < 35 mm/1^st hour are very useful in excluding infection (negative predictive value of 97%, excluding peri-prosthetic fractures and inflammatory joint disease), but raised inflammatory markers are less accurate in predicting infection.

To determine the ten-year survivorship of the Original M E Muller Straight Stem Total Hip Replacement System with emphasis on the longevity of the femoral component in accordance with guidelines published by the National Institute of Clinical Excellence, 266 consecutive hip arthroplasties using the above prosthesis were performed by the senior author between 1983 and 1992. 24 patients were lost to follow-up. Of the remaining 242 patients 80 were male and 162 female. The mean age was 67.49 years. The diagnosis for the majority of patients was osteoarthritis of the hip joint. Pre-operative planning was carried out and the patients were scored using Charnley’s modification of the d’ Aubigne and Postel numerical grading system A mono-bloc stem with a 32-millimeter head used via the trans gluteal approach recommended by Muller. Following discharge serial follow-up consisted of both clinical and radiological evaluation. The data was prospectively stored on a Microsoft access database. The survival of the prosthesis using revision for aseptic loosening as an end-point was calculated by actuarial analysis.

135 patients attended their ten-year follow-up. 97% of patients had good to excellent pain relief and improvement in movement of the joint following surgery. 38% had good to excellent mobility with the remaining having restricted mobility due to associated co-morbid factors. Only in 3% of patients was mobility restricted as a result of the arthroplasty. 7 revisions were carried out for aseptic loosening, all as a result of failure of the acetabular component. The cumulative survival for this hip replacement system was 95.9% and that for the femoral component was 100% at 10 years.

The Muller Straight Stem femoral component is based on a press-fit concept and gives predictable long-term results when recommended surgical technique is followed. This series confirms the reliability of the stem design and satisfies the NICE guidelines.

This in-vitro study was conducted to determine the effect of rotator cuff tears on joint kinematics. A shoulder simulator produced unconstrained active abduction of the humerus. Three sequential 1cm lesions were created, the first two in the supraspinatus tendon and the third in the subscapularis tendon. The plane of abduction moved posteriorly and became more abnormal throughout abduction as the size of the tear increased. It is concluded that in order to generate the same motions achieved by the intact joint other muscle groups must be employed, inevitably resulting in altered joint loading.

This in-vitro study was conducted to determine the effect of simulated progressive tears of the rotator cuff on active glenohumeral joint kinematics.

Five cadaveric shoulders were tested using a shoulder simulator designed to produce unconstrained active motion of the humerus. Forces were applied to simulate loading of the supraspinatus, subscapularis, infraspinatus/teres minor, anterior, middle, and posterior deltoid muscles based upon variable ratios of electromyographic data and average physiological cross-sectional area of the muscles. Three sequential 1cm lesions were created, the first two in the supraspinatus tendon and the third in the subscapularis tendon. Simulated active glenohumeral abduction was performed following the creation of each lesion. Five successive tests were performed to quantify repeatability.

The plane of abduction moved posteriorly and became more abnormal throughout abduction as the size of the lesion increased (p=0.01) (Figure 1).

In order to generate the same motions achieved with an intact rotator cuff other muscle groups must be employed, inevitably resulting in altered joint loading.

A better understanding of the effects that rotator cuff tears have on the kinematics of the glenohumeral joint may result in the development of innovative rehabilitation strategies to compensate for this change in muscle balance and improve the clinical outcomes.

Please contact author for diagram and/or graph.

The generally-accepted treatment for large, displaced fractures of the glenoid associated with traumatic anterior dislocation of the shoulder is operative repair. In this study, 14 consecutive patients with large (> 5 mm), displaced (> 2 mm) anteroinferior glenoid rim fractures were treated non-operatively if post-reduction radiographs showed a centred glenohumeral joint.

After a mean follow-up of 5.6 years (2.8 to 8.4), the mean Constant score and subjective shoulder value were 98% (90% to 100%) and 97% (90% to 100%), respectively. There were no redislocations or subluxations, and the apprehension test was negative. All fragments healed with an average intra-articular step of 3.0 mm (0.5 to 11). No patient had symptoms of osteoarthritis, which was mild in two shoulders and moderate in one.

Traumatic anterior dislocation of the shoulder, associated with a large displaced glenoid rim fracture can be successfully treated non-operatively, providing the glenohumeral joint is concentrically reduced on the anteroposterior radiograph.

Allografts of bone from the femoral head are often used in orthopaedic procedures. Although the donated heads are thoroughly tested microscopically before release by the bone bank, some surgeons take additional cultures in the operating theatre before implantation. There is no consensus about the need to take these cultures. We retrospectively assessed the clinical significance of the implantation of positive-cultured bone allografts. The contamination rate at retrieval of the allografts was 6.4% in our bone bank. Intra-operative cultures were taken from 426 femoral head allografts before implantation; 48 (11.3%) had a positive culture. The most frequently encountered micro-organism was coagulase-negative staphylococcus. Deep infection occurred in two of the 48 patients (4.2%). In only one was it likely that the same micro-organism caused the contamination and the subsequent infection.

In our study, the rate of infection in patients receiving positive-cultured allografts at implantation was not higher than the overall rate of infection in allograft surgery suggesting that the positive cultures at implantation probably represent contamination and that the taking of additional cultures is not useful.

Introduction We report the early results of a series of 80 primary total knee replacements (TKRs) using a trabecular metal tibial component (TMT).

Methods Significant tibial bone loss and scarcity of kit were the only reasons for patients not receiving a TMT. Age, sex, diagnosis and body mass index (BMI) were recorded. Patients were scored pre-operatively using the Oxford Knee and SF-12 scores. These were repeated at subsequent clinical follow up where standard X-rays were also taken. Range of movement was estimated using a goniometer and stability assessed clinically. This regimen was identical to that in place for the standard knee previously used by the senior author with a cemented tibial component and this group is used in comparison as possible.

Results To date there are 80 TMT knees in the series with 36 standard cemented TKRs in comparison. The mean age of the whole series is 70 years (20–90) with no difference between the groups. Sixty five per cent of the series were female. All bar three patients had osteoarthritis. The mean BMI was 30.3 (20.9–46.2). The mean pre-op Oxford score was 45.8 in the TMT group and 44.5 in the cemented group. At a mean follow up of 13.3 (9–17) months in the TMT group and 18.7 (9–19) months in the cemented group this fell to 22.5 and 20.5 respectively. The physical component of the SF-12 score improved from 27.3 to 40.7 in the TMT group and from 27.5 to 45.5 in the cemented group. There was no statistical difference between the groups using either score. The mean amount of flexion pre-operatively was 106 (65–135) degrees for the series. This was maintained postoperatively at 105 degrees (70–125) with no difference between the groups. There was one deep infection in the cemented group that underwent revision and one non-fatal pulmonary embolus in the cemented group. There were no worrying radiological signs in either group.

Conclusion Trabecular metal is made from elemental tantalum. The TMT is an uncemented component with a truly porous structure for bone ingrowth and a modulus of elasticity equivalent to bone that allows physiological transfer of stresses. The early clinical and radiological results are equal to a cemented prosthesis. Further follow up is required to see whether this is maintained over time.

We present four patients who had sustained a traumatic dislocation of the atlanto-occipital joint. The diagnosis was initially missed in two patients. One patient, who was neurologically intact, was treated non-operatively. The remaining three recovered neurologically after an occipitocervical fusion. Early recognition of the injury, especially in multiply-injured patients with head injuries, and timely management may improve survival and neurological recovery.

We prospectively investigated a consecutive series of ten patients undergoing a cemented primary total hip replacement (THR) for osteoarthritis in order to establish the elution characteristics of Simplex-tobramycin bone cement (Howmedica, Limerick, Ireland). Specimens of blood, urine and drainage fluid were collected for 72 hours postoperatively. Very high concentrations of tobramycin were found in the drainage fluid, with mean levels at one hour of 103 mg/l, which steadily declined to 15.1 mg/l after 48 hours. The mean serum tobramycin levels reached a peak of 0.94 mg/l at three hours and declined rapidly to 0.2 mg/l by 48 hours. The mean urinary tobramycin levels peaked at 57.8 mg/l at 12 hours with a rapid decline to 12.6 mg/l by 24 hours.

There was a direct correlation between the amount of tobramycin bone cement which was implanted and the amount of tobramycin systemically absorbed. Excellent local delivery was achieved with minimal systemic concentrations. Simplex-tobramycin bone cement is an efficient and safe method for the delivery of antibiotics after THR.

Among two hundred and twenty hemivertebrae in our files we performed over a period of eighteen years sixty nine hemivertebrae (HV) excision. Only H.V. with evidence of curve progression were operated on. The technique was a one stage anterior and posterior approach plus convex anterior and posterior arthrodesis plus convex posterior instrumentation using in the more recents cases a baby C.D.

Material: The location of the H.V. was thoraco-lumbar in twenty five cases, lumbar in twenty nine and lumbo-sacral in fifteen. Thirty two free, thirty six hemifused and only one fused H.V. were operated on. The sex ratio was 35 males and 34 females. Associarted malformations were numerous. If the rate of visceral associated malformations is rather the same whatever was the location of the H.V. ( 40% ) the number of associated spine malformations decrease from cranial to caudal ( 60% for thoraco-lumbar H.V. versus 13 % for lumbo-sacral H.V.) The mean age at surgery was 3Y 3M ( 1Y- 9Y) with a mean F.U. of 5Y ( 6M-18Y) for the 25 thoraco-lumbar H.V., respectively 3Y3M ( 1Y- 8Y3M) for the mean age at surgery and 5Y ( 1M-17Y5M) for the average F.U.for the 29 lumbar H.V. and 5Y1M (1M-10Y4M) for surgery and 7Y (1M-18Y3M) for F.U. for the remaining 15 lumbo-sacral H.V.

Results: 8 complications were encountered: 4 hardware failures, 1 sepsis, 1 transient paresthesia of the tibial nerve, 1 partial loss of power in the tibialis anterior and 1 valgus deformity following fibular bone grafting. For the 25 thoraco-lumbar H.V. the average scoliosis Cobb angle pre operatively was 38° ( 18°/ 75°) and at F.U. 24° ( 0°/ 76°) . The mean kyphosis Cobb angle was 24° ( -20°/ 54°) pre operatively and 25° (-16°/60°) at F.U. For the 29 lumbar H.V. the mean scoliosis Cobb angle was 35° (16°/58°) pre operatively and 10° (0°/38°) at F.U.The average kyphosis Cobb angle was -2°( -45°/20°) pre operatively and -6° (-42°/22°) at F.U. For the remaining 15 lumbo-sacral H.V. the average scoliosis Cobb angle was 30° (18°/40°) pre operatively and 13° (2°/32°) at F.U. The mean kyphosis Cobb angle was -22°(-54°/0°) pre operatively and -25°(-64°/-8°) at F.U. H.V. excision is in our opinion the best procedure to treat thoraco-lumbar,lumbar and lumbo-sacral H.V. as far as there is evidence of curve progression. The appropriate age to perform this kind of surgery is before three years of age.

We wished to see if Orthopaedic Surgeons are using the current evidence with regard to the use of drains in knee arthroplasty. A questionnaire was faxed to UK members of BASK.

We had a 71. 7% response rate (160 responses out of 223). For primary TKR, 89. 5% always use a drain. 42. 1% removed their drains at between 24 and 48 hours. The commonest reason for using drains was to prevent haematoma or haemarthrosis development.

The study suggests that the majority of BASK members do not practice evidence based medicine with regard to the use of knee drains.

Abstract: With the current shift in recommended practice towards being evidence based, we wished to see if Orthopaedic surgeons are using the current evidence with regards to the use of drains in knee arthroplasty.

Method: A questionnaire was faxed to all UK members of BASK to ascertain their current practice regarding the use of drains in knee arthroplasty and the rationale for their drain policy.

Results: The BASK members handbook identified 231 UK members and a questionnaire was faxed to them. 160 replies were received, of which 8 were excluded from analysis as they were either retired or non-surgeons. This gave a 68.2% response rate (1 52 results out of 223).

Drain usage:

Primary TKR: Always 136(89.5%); Sometimes 13(8.5%), Never 3(2.0%).

Revision TKR: Always 141(94.6%); Sometimes 3 (2.0%); Never 5(3.4%); Not applicable 3.

Unicompartmental: Always 66(57.9%); Sometimes 28(24.6%); Never 20(17.5%); Not applicable 3.1.

Hours drain removed at:

< 24 hours 77(50.7%); 24–48 hours 64(42.1%);

> 48 hours 4(2.6%); No answer 7(4.6%).

Rationale for drain use:

Prevent wound haematoma/haemarthrosis 74; personal reasons 27; to allow retransfusion 20; evidence based 12; despite evidence 5.

29.6% of the responders are currently using cell salvage drains, and a further 7.9% are keen to start using cell salvage drains when the circumstances in their hospitals change to allow them to do so.

Conclusion: The results of our questionnaire have shown that for primary TKR 89.5% always use a drain. With regard to the duration of drainage, 42.1 % of the respondents removed their drains at between 24 and 48 hours. The commonest reason given for the use of drains in total knee arthroplasty was to prevent haematorna or haemarthrosis development. However the published literature does not support these practices and beliefs. Only 12 people said that their practice was evidence based. We therefore have to conclude that the majority of practising members of BASK do not practice evidence based medicine with regard to the use of drains in knee arthroplasty.