MRI was used to diagnose occult hip pathology in patients with a clinically suspected femoral neck fracture where no abnormality was detected on plain x-ray. All patients admitted into our unit with post traumatic hip pain, an inability to weight bear, and no abnormality found on a series of plain radiographs, underwent an MRI scan of the pelvis and affected hip to look for an occult femoral neck fracture.

The study included 102 consecutive patients who were prospectively studied over a 10 year period between 1997 and 2007. Four patients were excluded due to contraindications or an inability to tolerate having an MRI scan. Of the remaining 98 patients 81 had abnormalities detected (83%). 42 of these patients had evidence of a proximal femoral fracture. 23 patients underwent an operative procedure.

Eight incomplete intertrochanteric fractures were treated non-operatively with good results. One patient had a primary diagnosis of malignancy made on the basis of the MRI scan. One patient had a known primary malignancy but this was the first diagnosis of bony metastatic disease. Seventy five patients were scanned within 48 hours of admission (average 2.4 days).

The use of MRI in our unit was felt to be appropriate in patients with a high suspicion of proximal femoral fracture. Our results show that there is a significant incidence of fractures that are not apparent on plain x-rays. MRI led to early diagnosis and initiation of definitive management, potentially reducing cost and complications of immobility. It was most useful in showing the extent of the fracture, and picked up on other occult pathologies of the hip and pelvis. We recommend stabilisation of femoral neck fractures and non operative management of all incomplete intertrochanteric fractures if able to non weight bear. There must be a high index of suspicion of undiagnosed malignancy

Spontaneous osteonecrosis of the knee (SONK) is a distinct clinical condition occurring in patients without any associated risk factors. There is controversy as to the best method of treatment, and the available literature would suggest that patients with SONK have a worse outcome. We evaluated the clinical and radiographic outcomes of unicompartmental knee arthroplasty using Oxford prosthesis in patients with spontaneous osteonecrosis

Between September 2002 and March 2008, 20 knees (18 patients) with SONK were treated with Oxford unicompartmental knee arthroplasty. There were fifteen women and three men with a mean age of 61.1 years old. The mean follow up was 37 months. The clinical assessment was performed using the American knee society score rating system. The preoperative radiography and MRI were analyzed according to size and stage of the osteonecrotic lesion and the osteoarthritic changes. Postoperatively, new osteonecrotic lesion, loosening of implant, subsidence, arthritic changes of other compartment were recorded.

The mean preoperative knee score and the knee function score were 52.5 and 56.0 points, respectively. The knee score was improved to 89.2 points (p < 0.05) and the knee function score was also improved to 85.2 points (p < 0.05) at last follow up. There were no implant failures. There was no new necrotic lesion in the lateral compartment, loosening, subsidence and arthritic change.

The Oxford Unicompartmental knee arthroplasty for spontaneous osteonecrosis of the knee provided satisfactory clinical and radiological results in a short to medium term. However, a longer term follow up will be needed.

Our center has performed hip replacement arthroplasties since 1997. The purpose of this study was to assess the long term clinicoradiological results of a total hip replacement using the double tapered Mallory-Head system.

The results of a consecutive series of 81 total hip replacements in 75 patients were reviewed three to eleven years (average eight years) postoperatively. The diagnosis were avascular necrosis for 46 hips (57%), osteoarthritis for 12 hips (15%), RA for 9 hips (11%), and others. The clinical result was evaluated on the basis of the modified Harris hip score, modified Merle d’Aubigné-Postel score. A detailed radiographic analysis was also performed.

The average modified Harris hip score improved from 56 points to 92 points. The average modified Merle d’Aubigné-Postel score was 15 points at the latest follow up, and 55 hips(68%) were classified as the clinical grades of excellent or good results. Two acetabular components were revised because of loosening, and one was revised because of recurrent dislocation.

We concluded that the clinical and radiological evaluations of the total hip replacements, using the Mal-lory-Head system showed good results with mid-term follow-up.

The purpose of this study was to review the total ankle arthroplasties performed in consecutive series of 78 ankles and to determine the short-term results in cases with over 12 months follow-up. Preoperative diagnoses were post-traumatic osteoarthritis in 40 ankles (51.3%), primary osteoarthritis in 32 ankles (41.0%), and systemic arthritis in six ankles (7.7%). HINTEGRA^® (Newdeal SA, Lyon, France) total ankle system was used in all cases

Fifty-five total ankle arthroplasties including four revision cases, followed up for over 12 months (range, 13~49 months) were included in this study. Ankles were divided into three groups according to the coronal plane deformity in preoperative standing ankle AP radiograph; Varus (≥10°; 20 ankles (39.2%)), neutral (< 10° varus or valgus; 25 ankles (49%)), and valgus (≥10° valgus; 6 ankles (11.8%)). Various additional surgeries were performed simultaneously with the arthroplasty to correct the deformities; deltoid ligament release (25 cases), posterior tibialis tendon lengthening (2 cases), peroneus longus tendon transfer to brevis (5 cases), lateral ankle reconstruction with modified Broström procedure (4 cases), lateral closed-wedge calcaneal osteotomy (3 cases), percutaneous heel cord lengthening (19 cases), and gastrocnemius recession (1 case). In one patient with severe valgus deformity, staged total ankle arthroplasty was conducted after primary triple arthrodesis.

Preoperative and postoperative visual analogue scale (VAS), American Orthopaedic Foot and Ankle Society (AOFAS) score, range of motion (ROM), as well as patient’s satisfaction and willingness to receive the operation again were evaluated The results were compared among the three groups. Serial radiographs were reviewed for any radiological changes.

AOFAS score has improved from 54.3 ± 11.4 pre-operatively to 79.2 ± 11.4 at last follow-up. VAS has decreased from 6.8 ± 1.6 to 3.2 ± 1.6. Mean improvement in ROM was 15.6 ± 16.2 degrees. Forty-eight cases (873%) were satisfied with excellent or good results and 49 cases (89.1 %) were willing to receive the operation again. No significant differences in the postoperative VAS (p=0.14), AOFAS score (p=0.79), and ROM (p=0.06) were found among the three groups. Hetero-topic ossifications were observed in 12 cases (23.5%) and periosteal reactions proximal to medial malleolus occurred in four cases (7.8%).

Perioperative complications include one intraoperative medial malleolus fracture which was successfully managed with two cannulated-screws, and one medial malleolar stress fracture at six weeks after surgery which has healed spontaneously. One case with osteolysis around tibial screws was managed with bone graft. One case with deep fungal infection was converted to arthrodesis after infection control. Four ankles had to be revised including three cases of polyethylene bearing change due to dislocation, and one case of tibial component and bearing change due to loosening. The patient with revised tibial component was converted to arthrodesis due to recurred loosening. The Kaplan-Meier cumulative survival rate was 90.9% at 12 months and 87.8% at 49 months postoperatively.

The short term clinical results of HINTEGRA ankles showed favorable results. No significant differences were observed among different groups of coronal plane deformities when adequate additional surgeries were performed simultaneously. Long term follow-up study is required.

Although the clinical manifestation of ONFH is well summarized as forms of various stages, its etiology, natural history or epidemiology has not been clearly elucidated yet. With this study, we wanted to find out the estimated annual incidence, epidemiologic characteristics and the effect of known risk factors of ONFH. Therefore we can understand the disease better to provide optimal management to the patients.

Among 133 189 patients who diagnosed as osteonecrosis of femoral head (ONFH) in database of national health insurance system in Korea from 2002 to 2006, three hundreds an eighty-two samples were randomly extracted with 5% error range in 95% confidence interval. With a structured worksheet, medical records and radiographs of each sample were reviewed at corresponding clinic or hospital by authors and trained orthopedic surgeons. With these data, we calculated the prevalence and associated risk factors.

The mean number of annual requests was 23 466. Among 382 samples, two hundreds and seventy-four were confirmed to have ONFH. Diagnostic accuracy was 71.7 %. Diagnosis was more accurate when the patient was male or hospitalized. After the logistic regression analysis, calculated diagnostic accuracy during 2002 and 2006 was 60.3% (51 823/85 987). The annual predicted number of cases of ONFH during this period was 14 103. It corresponds to 28.91 patients per 100 000 populations. Alcohol abuse was noted in 45% and 22% was related to use of steroid. 37% showed bilateral involvement. Bone graft procedures in any kind was the most frequently performed joint preserving procedure.

With this, the first epidemiologic study for ONFH in Korea, we estimated nationwide annual prevalence of ONFH as 28.91 per 100,000 populations during 2002 and 2006. There is an absolute male predominance. Alcohol abuse is the most frequent risk factors. We believe that this result can serve as a baseline data for understanding the epidemiology, clinical characteristics and treatment of ONFH.

Modular femoral stem provides significant flexibility in total hip revision arthroplasty. There have been few clinical studies that have dealt with modular stem. We have evaluated the clinical and radiographic performance of 59 patients with distal fix modular Link MP stem. The average follow-up period was 6.4 years. The average Harris hip score was improved from 47 to 87.6. Of 19 patients with trochanteric osteotomy, greater trochanter was displaced in four patients. Re-revision was done to five patients. Three were for subsidence, one of them showed dissociation of the coupling part and the other two were for a nonunion of osteotomy site. There was no statistical relation (p=0.40) between stem subsidence and bone deficiency; the subsidence may have been too small for the canal. As a result of last follow-up, survival rate was 91.5 %(CI 95%, 89–101), but there was no case of recurrent dislocation or femoral stem fracture.

Purpose: The purpose of this study is to evaluate the clinical and radiological results of the total hip arthroplasty using the CLS stem, of which we were able to follow up for 15~20 years after operations.

Materials and Methods: Among 104 patients who underwent the total hip arthroplasty using the CLS stem from 1988 to August 1993, we evaluated the clinical and radiological results of 65 hips of 51 patients, which were able to be followed up for more than 15 years. The average age at the operation was 45 years old (22~62 years old) and the average follow-up duration was 17 years and 2 months (15 years~20 years 5 months). The majority of preoperative diagnoses was avascular necrosis of femoral head with 52 cases (80%), followed by osteoarthritis with 7 cases (11%) and the other 6 cases. Used as acetabular components were 15 cases of the Expansion cup, 26 cases of the HG II cup, 11 cases of the CLW cup, 2 cases of the Spherical cup and 11 cases of Bipolar cup (54 cases of the total hip arthroplasty and 11cases of bipolar hemiarthroplasty).

Results: No femoral stem revision was performed. The average Harris hip score improved from 52.2 preopera-tively to 94.3 at the final follow-up. There was no patient who complained a severe thigh pain. Radiographically, small osteolytic lesions were found in 23 cases (35.4%), endosteal bone formation in 63 cases (96.9%), calcar femoral atrophy in 7 cases (10.8%) and cortical hypertrophy in 15 cases (23.1%). Acetabular cup loosening occurred in 4 cases and liner dissociation occurred in 2 cases among 54 total hip arthroplasty cases, and the acetabular cup revisions were performed in those cases and a liner change was additionally performed in 1 case. The conversion total hip arthroplasty was performed in 1 case among 11 bipolar hemiarthroplasty cases due to a snap fit design failure. Complications included a periprosthetic fracture (1 case) and a dislocation (1 case). The periprosthetic fracture, which was complicated due to a slip-down injury 17 years after the THA, was treated by an open reduction and internal fixation. The dislocation, which was complicated 13 years after THA, was treated by a manual reduction.

Conclusion: Fifteen to twenty year follow-up results of total hip arthroplasty using the CLS femoral stem showed an excellent result without any femoral stem revision.

An MR scan was performed on all patients who presented to our hospital with a clinical diagnosis of a fracture of the proximal femur, but who had no abnormality on plain radiographs. This was a prospective study of 102 consecutive patients over a ten-year period. There were 98 patients who fulfilled our inclusion criteria, of whom 75 were scanned within 48 hours of admission, with an overall mean time between admission and scanning of 2.4 days (0 to 10). A total of 81 patients (83%) had abnormalities detected on MRI; 23 (23%) required operative management.

The use of MRI led to the early diagnosis and treatment of occult hip pathology. We recommend that incomplete intertrochanteric fractures are managed non-operatively with protected weight-bearing. The study illustrates the high incidence of fractures which are not apparent on plain radiographs, and shows that MRI is useful when diagnosing other pathology such as malignancy, which may not be apparent on plain films.

Introduction: Interest in the relationships between subchondral bone pathology and cartilage breakdown has been stimulated by the observations that bone marrow edema (BME) is related to both pain and bone remodeling and that the progression of cartilage lesions is greater in joints with significant BME. The hypothesis of this study is that changes in perfusion in subchondral bone bear a functional relationship to bone remodeling and cartilage degradation and are a part of a physicochemical signaling mechanism to osteoblasts. We have utilized dynamic, contrast-enhanced magnetic resonance imaging (MRI) to assess perfusion and BME in osteoarthritis (OA) and osteonecrosis (ON).

Methods: Investigation of marrow perfusion in BME was performed in both the Dunkin-Hartley guinea pig model of OA patients and cohort of 26 control patients. The human study was performed on a 1.5T magnet using a dedicated surface coil and STIR [3500/17/150 (TR/TE/TI)] and VIBE [5.50/2.89 (TR/TE); 10° (flip angle)] pulse sequences. We determined pharmacokinetic parameters of marrow perfusion according to the two compartment model of Brix, which is characterized by rate and volume transfer constants that can be derived mathematically from time-signal intensity curves.

Results: In the guinea pig model, inflow slope was similar at all ages; kel was decreased in the affected medial, but not in the normal lateral, tibia indicating reduced perfusion and outflow obstruction. Comparison of BME and perfusion metrics with morphological features (Mankin scores and subchondral bone plate thickness) at the medial tibia demonstrates that changes in perfusion dynamics precede bone remodeling and cartilage breakdown by several months. Compared to normal marrow, kinetic parameters of contrast-enhancement in areas of BME included higher initial slope (p< .001), higher A (p< .001), lower kep (p=.004), and lower kel (p< .001). In areas of BME around ON, there was significantly lower A (p=.009) and lower kel (p=.04) compared to BME adjacent to OA, but no significant difference in either initial slope (p=.06) or kep (p=.26).

Discussion: To our knowledge, these are the first reports of the use of dynamic, enhanced-MRI to characterize bone marrow perfusion in BME associated with OA and ON. In the Dunkin-Hartley guinea pig, reduced perfusion in BME temporally precede alterations in bone remodeling and appearance of cartilage lesions, and are spatially localized to bone subjacent to eventual cartilage lesions. We have also demonstrated similar perfusion kinetics associated with BME in human ON and OA. Calculations of intraosseous pressure associated with outflow obstruction and decreased perfusion are consistent with measurements made in end-stage ON and OA. Osteoblasts are known to be responsive to flow, pressure, and pO2. Increased pressure and decreased flow associated with outflow obstruction may constitute physicochemical signals to osteoblasts which result in changes in cytokine expression and contribute to trabecular remodeling and cartilage breakdown.

Introduction: The aim of this study was to report the clinical and radiographic results of a modified transtrochanteric rotational osteotomy (MTRO) for osteonecrosis of the femoral head.

Materials and Methods: A MTRO was performed in 43 hips with osteonecrosis. The mean age was 34 years (range, 20 to 51 years). According to the classification system of the Association Research Circulation Osseous, 17 hips were stage 2 and 26 stage 3. We performed simple MTRO in 15 cases, combination of MTRO and simple bone grafting in 3 cases, and a combination of MTRO and muscle pedicle bone grafting in 25 cases.

Results: At a mean 37 months after surgery, there was further collapse of the femoral head in 3 hips. All these lesions were in the lateral location, and 2 were large lesions. One of these 3 hips was converted to a total hip arthroplasty. The overall survival rate was 93 percent. Among the surviving 40 cases, excellent results were obtained in 26 hips, good results in 11, and fair results in 3 hips.

Conclusion: A MTRO is an effective method for delaying the progression of collapse in the treatment of osteonecrosis of the femoral head in selected cases.

Sprains and strains result from collagen fibre overextension. This study investigated changes in the molecular state of collagen due to overextension damage, thereby gaining insight into tissue degeneration and cellular detection of damage. Overextension results in intermolecular and intrafibrillar sliding, detected with x-ray diffraction. Tendon rupture results in increased susceptibility to proteolytic enzymes. These observations and contemporary theory concerning collagen fibre stability lead to the hypothesis that sub-rupture overextension should result in reduced thermal stability of fibrous collagen.

Tendons were harvested from steer tails. Each provided a specimen for control and for overextension. Sub-rupture overextension at 1%/s strain rate was accomplished on a mechanical testing system, under the control of custom software, until the slope of the force-deformation curve was approximately zero (before complete failure). Two loading treatments were tested: one-cycle and five-cycles. Two specimen types were tested: native tendons ± NaBH4 crosslink stabilization. Tendons in each of the four groups (2x2) were paired by originating tail. Thermal stability was assessed in terms of denaturation temperature (Td) using hydrothermal isometric tension testing. Specimens were held at constant length and heated from ambient temperature to 90degC. Td was defined as the temperature where load suddenly increased due to molecular unraveling and attempted shrinkage.

Overextension of native specimens reduced the thermal stability of the collagen (p< 0.0001) and five-cycles had a still greater effect (p=0.03). Td of controls was 64.5±1.0degC (mean±SD). After one-cycle, Td dropped to 63.2±1.0degC and, after five-cycles, Td dropped to 61.8±2.0degC. For stabilised tendons, the effect of multiple cycles was lost (p=0.08) but overstretching decreased Td by ~2degC (p< 0.0001).

This study confirms that the molecular state of collagen is altered by overextension damage, reducing Td by up to 10% of the expected range (37–65degC) in our experiments. This is thought to occur due to intermolecular sliding that liberates specific domains on the molecules, lowering the activation energy for uncoiling. These domains may also be key targets in degeneration and cell-collagen signaling.

Tendon disease causes widespread morbidity ranging from mild pain to catastrophic end-stage rupture. The pathophysiology of tendon disease is not certain. An overuse exercise model was developed using rats with the aim of developing tissue with histological, biochemical and biomechanical features similar to those in human tendinosis. Results indicate that the biological response to over-exercise of the rat Achilles tendon is similar to the literature description of pathological specimens of human with disease. Biochemical and histological analysis of the rat Achilles tendons suggest that the patho-physiology is more consistent with a repair response than with a classical inflammatory response.

Tendon disease causes widespread morbidity ranging from mild pain to catastrophic end-stage rupture and the pathophysiology of tendon disease is not certain.

To develop an overuse exercise animal model to study the pathophysiology of Achilles tendon disease.

Experimental rats were subjected to an over-exercise running regime, while control rats were maintained under normal cage activity. Achilles tendons were analyzed for histological features, glycosaminoglycan content, collagen content, collagen subtype, collagen crosslinking (hydrothermal isometric tension testing), and mechanical properties.

Experimental rat Achilles tendons demonstrated: increased nuclear numbers per high-power field (527 vs. 392, p < 0.05), decreased semi-quantitative grade for collagen organization (2.9 vs. 3.7, p < 0.05) and decreased semi-quantitative grade for collagen staining (1.9 vs 3.5, p < 0.05). The total collagen content remained unchanged (84.3 vs. 89.0% p=0.38), while the glycosaminoglycan content was increased (17.5 vs. 9.0% p=0.02). Increased levels of collagen type III were not demonstrated, however. Experimental tendons were determined to have distinct differences in the collagen crosslinking patterns, with reduced total cross links and a greater population of immature, hydrolytically unstable cross links. These differences did not, however, translate into a decrease in ultimate tensile failure during mechanical testing (UTS of 77.8 vs. 88.8 N, p=0.26).

The histology and biochemistry observed in the experimental rat Achilles tendons were similar to those described in the literature on human Achilles tendon disease.

The rat Achilles tendon over-exercise model has demonstrated histopathology that was different from a control group and was consistent with the human literature for Achilles tendon disease.

Research Grants were received from the following organizations:

Canadian Orthopaedics Foundation

Tendinosis is a common problem causing wide spread morbidity ranging from mild symptoms of pain and limited mobility to catastrophic end stage rupture. The structural and mechanical properties of the rat Achilles tendon were investigated as groundwork for the development of a rat Achilles tendinosis model. This model will generate tendons afflicted with tendinosis that bear histological features identical to those observed in human tendinosis. Tissues afflicted with tendinosis derived from this model will be used in future studies to gain a better understanding of the biology of tendinosis and to evaluate various therapeutic intervention strategies.

The pathology underlying tendinosis is a continuum, with mild symptoms progressing toward catastrophic rupture; still, the corresponding biochemical and biomechanical progression is poorly understood.

We have developed a rat model for Achilles tendinosis, aiming to: (i) define for the first time the structural/mechanical features of the normal tendon and (ii) examine the histological changes with over-exercise.

Normal rat Achilles tendons were assayed via: hydroxyproline for total collagen, SDS-PAGE electrophoresis for collagen subtypes, thermoelastic testing for immature/mature collagen crosslinking, and tensile mechanical testing. As per Soslowsky in the rat rotator cuff, the over-exercise model used 10° uphill treadmill running over twelve weeks. Light histology under H& E staining and birefringence was assessed using a blinded, semi-quantitative scale.

The normal rat Achilles is 89.6 ± 10.6% (SD) collagen with a mean UTS of 5.29 ± 1.91 MPa (SD). Only type I collagen is evident in SDS-PAGE and immature collagen crosslinking is dominant demonstrated by

NaBH₄-reduction required to achieve a 90°C isotherm

in hydrothermal testing. The three, six and twelve-week over-exercise regimes produce increasing cell area density and decreasing collagen organization. Surprisingly, the proliferating cells do not seem to be fibroblast dominant and label with factor III antibody to human endothelial cells.

The normal Achilles tendon in young (eight weeks old) but mature rats is a strong, collagen-rich tissue; however, immature crosslinking suggests remodelling. We suspect that low type III collagen in the normal Achilles may increase significantly with inflammation. However, fibroblast proliferation may not be dominant.

Our rat Achilles tendon over-exercise model has demonstrated histopathology consistent with the human literature. With clear structural/mechanical characterization, future studies will focus on changes in these variables with disease tendons derived from the rat ten-dinosis model.

Funding: Research Grants were received from the following organizations: 1-Canadian Orthopaedics Foundation, 2-American Foot and Ankle Society, 3-Dalhousie University Department of Surgery, 4-Nova Scotia Capitol District Health Authority Research Fund

We present the clinical and radiological results of percutaneous vertebroplasty in the treatment of 58 vertebral compression fractures in 51 patients at a minimum follow-up of two years. Group 1 consisted of 39 patients, in whom there was no associated intravertebral cleft, whilst group 2 comprised 12 patients with an intravertebral cleft. The Oswestry disability index (ODI) and visual analogue scale (VAS) scores were recorded prospectively. The radiological evidence of kyphotic deformity, vertebral height, leakage of cement and bone resorption around the cement were studied restrospectively, both before and after operation and at the final follow-up.

The ODI and VAS scores in both groups decreased after treatment, but the mean score in group 2 was higher than that in group 1 (p = 0.02 (ODI), p = 0.02 (VAS)). There was a greater initial correction of the kyphosis in group 2 than in group 1, although the difference was not statistically significant. However, loss of correction was greater in group 2. Leakage of cement was seen in 24 (41.4%) of 58 vertebrae (group 1, 32.6% (15 of 46); group 2, 75% (9 of 12)), mainly of type B through the basal vertebral vein in group 1 and of type C through the cortical defect in group 2. Resorption of bone around the cement was seen in three vertebrae in group 2 and in one in group 1. There were seven adjacent vertebral fractures in group 1 and one in group 2.

Percutaneous vertebroplasty is an effective treatment for osteoporotic compression fractures with or without an intravertebral cleft. Nonetheless, higher rates of complications related to the cement must be recognised in patients in the presence of an intravertebral cleft.

Introduction: The use of a trans-physeal, trans-articular suture anchor across a joint as a means of internal stabilisation has not previously been described. This study assesses the damage caused by the procedure to the immature porcine hip.

Methods: Six twelve week old pigs underwent unilateral hip surgery. Anteroposterior pelvic radiographs were taken preoperatively and six weeks post-operatively. The acetabular index and diameter of the femoral head ossific nucleus of both hips were measured and compared. Specimens were analysed macroscopically for femoral head diameter, acetabular dimensions and for evidence of gross chondrolysis. Histological analysis was performed to assess the presence of articular chondrolysis and proximal femoral physeal arrest.

Results: In four out of six specimens the rate of change of the acetabular index slowed as compared to the unoperated side, though none worsened. The diameter of the femoral ossific nucleus continued to increase in size at a similar rate to the unoperated side on radiological examination. Similar findings were seen with the macroscopic analysis. Gross and histological analysis of the articular cartilage showed only local areas of chondrolysis, related to the drilling. Metaphyseal growth at the proximal femoral physis was unaffected by the procedure.

Discussion: The use of a trans-articular suture-anchor across the hip appears to cause marginal retardation of acetabular development in the normal hip. The trans-physeal approach to the hip does not appear to affect proximal femoral physeal or epiphyseal growth in the short-term, and the presence of a bioabsorbable suture within the joint did not result in chondrolysis.

Extensor Pollicis Longus (EPL) rupture occurs in 0.2 – 3% of fractures of the distal radius. The underlying mechanism is unknown. This study prospectively evaluates EPL and surrounding structures using high-resolution ultrasound (US) in patients with distal radius fracture 6 weeks after injury and correlates the findings with initial radiographic measurements.

US can assess tendon size, echogenicity and peak velocity, haematoma depth and thickness of the extensor retinaculum and tendon sheath. The normal wrist was examined as a control.

Results: 58 patients with mean age 54 yrs (39 female, 19 male), 28/58 underwent manipulation in the Emergency Department and 11/58 went to the Operating Theatre for fixation.

Radiographic measurements – AO classification: A-32, B-12 and C-14. 76% were undisplaced fractures with dorsal tilt less than 10.

Statistical analysis revealed that EPL tendon peak velocity is significantly slower on the fractured side (p=0.001). The extensor retinaculum thickness is greater (p=0.003) and the synovial sheath thickness is greater (p less than 0.001) on the fractured side. Synovial sheath thickness was also found to be significantly greater in the intra-articular fractures (p=0.03) and the undisplaced fractures (p=0.03).

Conclusions: This study correlates patterns of distal radius fracture that are associated with US changes in EPL tendon.

As expected, the peak tendon velocity is reduced following fracture, but this is still significant at 6 weeks. This could be associated with impaired diffusion of nutrients within the synovial sheath.

There is also persistent soft tissue swelling with significantly increased extensor retinaculum and synovial sheath thickness. This is a protective response to trauma, but we propose that this could interfere with the already tenuous blood supply of the EPL tendon. It could also reduce diffusion of nutrients within the tendon sheath, particularly in undisplaced fractures, where the extensor retinaculum is not torn and any increased pressure may not be dispersed.

The study is ongoing with the aim to be able to identify patients at risk for EPL rupture and potentially be able to prevent it by early surgical decompression.

Introduction: Long term performance of total knee replacements is governed by wear of ultra-high molecular weight polyethylene (UHMWPE) which leads to aseptic loosening of the implant. Little has been done to reduce wear due to the femoral component properties in knee joint replacement. Scratching of the femoral component has been identified in retrieved knee replacements. Using a material that has a higher scratch resistance than current metals may reduce the rate of UHMWPE wear in knee replacements. In this study we investigated the effects of using an oxidized Zirconium femoral component has on wear in knee replacements.

Methods: Total knee replacements made of CoCr and oxidised zirconium were tested in a four station, six degrees of motion knee simulator for 4 million cycles. The surface roughness values (Ra, Rz and Sm) for the metal counterfaces was measured through the test. In addition gravimetric wear of the UHMWPE inserts was recorded. Scanning electron microscopy of the two counterface surfaces was performed to provide information on possible mechanisms involved in the wear process.

Results: The starting surface roughness for both CoCr and oxidised zirconium were similar (Ra=0.03m). Oxidised zirconium was significantly more scratch resistant than CoCr; Ra (mean average roughness) of 0.7m compared to 0.43m (p< < 0.01) at end of test, with similar differences in the other surface roughness parameters. This was accompanied by a 4 fold reduction in wear of UHMWPE 49.60mg to 12.48mg (p=0.02).

SEM analysis of the surfaces of the metals revealed large deep scratches of the CoCr implants which were aligned in the A-P sliding direction. Barium sulphate particles were seen embedded in the surface of the femoral component. Voids were seen in the surface of the cobalt chrome and particles of silicate polishing powder were seen in these voids. There was also evidence of scratches originating at these voids. By contrast oxidised zirconium, showed small amounts of superficial scratching with an intact surface and no evidence of third body particles.

Summary and conclusions: Oxidised zirconium leads to a reduction in wear of UHMWPE due to its increased resistance to third body wear. It has the potential to increase the longevity of total knee replacements by reducing wear of UHMWPE. Additionally, polishing powder used in the manufacture of cobalt chrome femoral components of knee joint replacements is a potential source of third body particles.

Introduction and Aims: While successful long-term results have been shown for ligament reconstruction–tendon interposition arthroplasty for treatment of thumb basal joint osteoarthritis, the need for invasive ligament reconstruction has not been established. In this study we describe long-term results utilising the technique of tendon interposition arthroplasty with dynamic tendon transfer and capsulorrhaphy.

Method: Twenty-four thumbs (21 patients) were evaluated at an average of 7.1 years (1.8–19.5 years) post-procedure. Capsulorrhaphy was performed utilising APL tendon slips where tissue was insufficient. The APB origin was advanced via tendon transfer (FCR to APB), providing a stabilising abductor moment. Subjective assessment was performed using Visual Analogue Scores (VAS), Disabilities of Arm, Shoulder, Hand (DASH) scores, and patient satisfaction scales. Objective assessment included post-operative range of motion (ROM), grip/pinch strength, and radiographs for interposition arthroplasty height.

Results: Twenty of 21 patients (95%) were satisfied and described results as either good or excellent. Twenty of 21 patients (95%) would undergo surgery again. Mean VAS was 8.7 at rest and 10.2 with activity (0, no pain; 100, maximum pain). Mean DASH score was 16.9 (range from 0, no difficulty performing daily tasks to 100, unable to perform daily tasks). ROM, grip, lateral and tip pinch strengths were comparable with those of the contralateral thumb. AP radiographs showed preservation in 12 of 12 patients (100%). Fourteen of 21 patients received the procedure on their dominant hand.

Conclusion: Treatment of basal joint osteoarthritis with our technique provided stable and functional reconstructions, resulting in excellent pain relief. Results were comparable to, or better than, those previously cited in the literature for alternative procedures. These results suggest that dogma requiring static ligament reconstruction or suspension may need to be re-evaluated.

Introduction and Aims: The volar carpal ganglion (VCG) is a common benign tumor of the hand complicated by multiple recurrences with conventional treatment. Despite being a common condition, we know of no report describing post-operative functional outcome. We evaluated functional outcome, pain, scarring, and recurrence after VCG excision in the last 15 years.

Method: Twenty-eight patients were considered for inclusion in this study. All patients had been surgically treated for volar carpal ganglia in the last 15 years. Of these, 16 were available for follow-up after exclusion of patients who had since deceased, moved, or were otherwise lost to follow-up. Mean follow-up period was 55 months (nine–135 months). Functional outcome of the upper extremity was evaluated using the standard DASH questionnaire. DASH scores can range from zero (no difficulty in performing daily tasks) to 100 (unable to perform daily tasks). Pain, scarring, and recurrence were also assessed.

Results: Sixteen patients who underwent surgical excision of their recurrent volar carpal ganglions were available for follow-up at the time of the study. They included six men and 10 women, with a mean age of 47 (range 11–70 years). The duration of symptoms prior to excision ranged from two to 50 months. Pain was the main reason for surgery while one patient reported that surgery was performed for cosmetic reasons. There were eight patients in the nine-month to three-year follow-up period and the average DASH score was 7.6. The four patients in the three to five-year follow-up period had an average DASH of 8.1. The four patients in the five plus years of follow-up had an average DASH of 1.7. The improvement in functional outcome correlated with time since surgery, however these differences were not statistically significant. Two of the 16 patients had recurrences within six months after excision. Increased pain was reported in these patients only. No patients complained of significant scarring post-operatively.

Conclusion: Multiple treatment modalities including aspiration and surgery are discussed in the literature with great outcome variability. Our series is the first long-term functional assessment after VCG excision. Thus, surgery is an option for treatment of this common condition as evidenced by low recurrence and DASH scores and high patient satisfaction.

Purpose: Using the finite element analysis, the authors analyze the effect of the articulating material properties of the total hip arthroplasty to stress and micro-motion of the proximal femur and the femoral stem.

Material and methods: The head (28mm) and the acetabular component (outer diameter = 54mm, liner thickness = 11.4mm) were considered as ceramic on ceramic, cramic on polyethylene, metal on metal, metal on polyethylene and metal on metal-polyethylene. The femur was modeled with different friction coefficients according to the different contact portion of the femoral stem, which was modeled after Omni fit HA #9(Osteonics, Allendale, NJ). Non-linear contact analysis was proceeded in human with body weight 70Kg at one leg standing and stair climbing.

Result: The maximal yield strength was always higher in hard-hard coupling. In one leg standing, the site of maximal yield strength was represented at the contact point of articulation. In stair climbing, the site of maximal yield strength was represented at the same site in hand on hard coupling but at the lateral aspect of the neck in hard-soft couplings. There were no changes in the patterns of stress distribution but the micro-motions were up to the limit of bone in growth in hard-hard coouplings.

Conclusion: The maximal yield strength and the micro-motions revealed different values according to the articulating materials. These findings were considered valuable information to postoperative management and longavity of the total hip prosthesis but requiring the following experimental and clinical study.