Introduction

Early clinical examination combined with MRI following a high ankle sprain allows accurate diagnosis of syndesmosis instability. However, patients often present late, and for chronic injuries clinical assessment is less reliable. Furthermore, in many centres MRI may be not be readily available. The aims of the current study were to define MRI characteristics associated with syndesmosis instability, and to determine whether MRI patterns differed according to time from injury.

Purpose

To review prospectively collected data on patients undergoing primary total hip arthroplasty utilizing two different cementless acetabular components.

To review prospectively collected data on patients undergoing primary total hip arthroplasty utilizing two different cementless acetabular components.

All patients undergoing primary total hip replacement surgery at our institution are entered prospectively into a database which includes history and physical examination, radiology, WOMAC and SF-36 scores. The patients are re-examined, re-x-rayed and re-scored at 3 months, 6 months and 1 year after surgery and yearly thereafter.

Using this database we are able to identify patients who have undergone total hip replacement using one of two geometric variants of the acetabular component. The first design is hemispherical and the second design has a peripheral rim expansion designed to increase initial press-fit stability.

Five hundred and twenty-seven consecutive primary total hip replacements were identified using either of the geometric variants of the acetabular component. Results at a mean of 7 years revealed a 95.6% survivorship with no significant difference between the two component designs with revision for aseptic loosening as the end point. Functional scores between the two groups of patients also demonstrated no statistically significant difference.

Radiologic assessment, however, showed a difference between the two designs. The hemispherical design which matches the reamer line-to-line had 80% complete osseointegration on final radiologic review while the second design with a peripheral rim expansion had only 57% complete osseointegration. This was statistically significant. The peripherally expanded components also had a greater number of screws inserted at the time of surgery, felt by us to be a reflection of initial surgeon dissatisfaction with component stability at the time of insertion of the component.

The difference in screw numbers was also statistically significant. This study demonstrates that a hemispherical design with line-to-line contact between the acetabular component surface and the acetabular bone is statistically superior in terms of bone ingrowth and probably statistically superior in terms of initial press-fit stability when compared to a peripherally expanded component.

Peripherally expanded components appear to offer no advantage over hemispherical components in terms of clinical outcome and are statistically inferior to hemispherical components in radiologic parameters at 7 years follow-up.

Purpose

To review prospectively collected data on patients undergoing primary total hip arthroplasty utilizing two different cementless acetabular components.

Tibiotalocalcaneal fusion is generally reserved for complex cases such as severe deformity or bone loss, infection, Charcot and revision procedures. Subsequently published series have been small and there are no studies comparing plate fixation and intramedullary nailing. We present the outcomes in the largest series to date and have also compared the union rate and complication rate between blade plate fixation (36) and intramedullary nailing (46). Both groups were well matched for patient and disease factors.

There was a non-statistically significant trend towards better outcomes with nails. Further analysis was conducted comparing the two fixation methods by the indication for surgery, there were no statistically significant differences, the reasons for these findings are discussed.

Introduction: This study aimed to determine the accuracy of computer navigation in simulated fixation of femoral neck and supracondylar femoral fractures using different sizes of guidewires and drills from commercially available cannulated screw systems.

Methods: Simulated fracture fixation was performed with 2.5mm, 2.8mm and 3.2mm threaded guidewires and 3.2mm and 5mm drill bits using 20 4th generation synthetic femurs. The drill or guide wire was inserted in the synthetic femurs, using fluoroscopy based computer navigation (24 drills/guidewires in each group). Pre and postoperative fluoroscopy images were acquired with the C-arm and synthetic bone in the same orientations. Virtual and real wire/drill positions were compared, and errors calculated for each diameter of drill/guidewire (sum AP + Lateral error (mm)). Errors were compared using a general linear model with Tukey adjustment for multiple comparisons. Statistical significance at a two-tailed p-value < 0.05.

Results: The mean error for the 5.0mm drill (3.20mm) was significantly less than all the threaded wires (p< 0.05). The mean error for the 3.2mm drill (5.68mm) was significantly less than the 2.5mm guidewire (9.27mm) p< 0.05, and less than the 2.8mm (8.19mm) and 3.2mm (7.14mm) threaded wires.

Discussion: For cannulated screws, the 3.2mm drill was the most accurate size tested. The most accurate drill, 5mm, would allow solid screw insertion. However, its large size may preclude screw repositioning, and unlike a cannulated screw, would not maintain fracture position whilst the screw was being inserted.

Introduction: This study compared the accuracy of reduction of intra-medullary nailed femoral shaft fractures, comparing conventional and computer navigation techniques.

Methods: Twenty femoral shaft fractures were created in human cadavers, with segmental defects ranging from 9–53mm in length. All fractures were fixed with antegrade 9mm diameter femoral nails on a radiolucent operating table. Five fractures (control) were fixed with conventional techniques. Fifteen fractures (study) were fixed with computer navigation, using fluoroscopic images of the normal femur to correct for length and rotation. The surgeon was blinded to defect size. Two landmark protocols were used in the study group referencing the piriform fossa (Group A, n=10) or proximal shaft axis (Group B, n=5). Postoperative CT scans, blindly reported by a musculoskeletal radiologist, were used to compare femoral length and rotation with the normal leg.

Results were analysed using ANOVA with 95% Confidence Intervals.

Results: The control and study groups were not statistically different with respect to age of cadaver or size of femoral defect. Results: The mean leg length discrepancy in the study groups were significantly less (3.6mm (95% CI 1.072 – 6.128) and 4.2mm (95% CI 0.63–7.75), compared with 9.8mm (95% CI 6.225 – 13.37) in the control group (p< 0.023). The mean torsional deformities in the study groups were 8.7 degrees (95% CI 4.282 – 13.12) and 5.6 degrees (95% CI -0.65 – 11.85), compared with 9 degrees (95% CI 2.752 – 15.25) in the control group (p=0.650). Within the navigated study group, length discrepancy was similar in subgroups 1 (3.6mm) and 2 (4.2mm). Torsion appeared more accurate in group 2 (5.6 degrees) than group 1 (8.7 degrees), although this was not statistically significant.

Discussion: Computer navigation significantly improves the accuracy of femoral shaft fracture fixation with regard to length. With further modifications to improve reduction of rotational deformity, it may be a useful technique in the treatment of femoral fractures.

The effect of cup geometry in uncemented Total Hip Arthroplasty has not been investigated. We reviewed the radiological and clinical results of 527 primary total hip arthroplasties. We assessed the bone ingrowth potential of two geometric variations of an uncemented cup and compared hydroxyappetite and porous coated shells.

Patients undergoing primary hip arthroplasty between 1997 and 2004 were prospectively entered into an arthroplasty database. Patients were reviewed at 1,2,4,5,8 and 10 years post surgery. Three acetabular shell types were used. These included hemispherical cups with porous or hydroxyapatite coating, and cups with peripheral expansion with porous coating. Radiographs with minimum 1-year follow-up were examined in 542 cases, using digital templating software. Radiographs were assessed for signs of bone in-growth, lucent lines, migration and polyethylene wear. Survivorship analysis was performed using Kaplan-Meier analysis with 95% confidence intervals. Radiological findings and cup type were analysed using Fishers exact test.

Radiological evidence of bone ingrowth was seen in 82% of hemispherical cups, compared with 59% of peripherally expanded cups, which was significant (p,0.05). Bone ingrowth was not affected by the presence of HA coating. The most common diagnoses were osteoarthritis (67%) and avascular necrosis (12%). The mean age was 56 years. Survivorship with revision or impending revision for aseptic loosening was 95.6% at 7 years (95%CI 1.0134-0.8987). The 3 revisions and 1 impending revision for loosening were in patients with avascular necrosis (3) or previous acetabular and femoral osteotomies for DDH (1), with a mean age of 44 years.

Hemispherical shells have improved radiographic outcome in comparison with peripherally expanded components. At 7 years, clinical results are similar for both components.

This study compared the accuracy of reduction of intra-medullary nailed femoral shaft fractures, comparing conventional and computer navigation techniques.

Twenty femoral shaft fractures were created in human cadavers, with segmental defects ranging from 9–53mm in length. All fractures were fixed with antegrade 9mm diameter femoral nails on a radiolucent operating table. Five fractures (control) were fixed with conventional techniques. Fifteen fractures (study) were fixed with computer navigation, using fluoroscopic images of the normal femur to correct for length and rotation. The surgeon was blinded to defect size. Two landmark protocols were used in the study group referencing the piriform fossa (n=10) or proximal shaft axis (n=5). Postoperative CT scans, blindly reported by a musculoskeletal radiologist, were used to compare femoral length and rotation with the normal leg. Results were analysed using the Wilcoxon two-sample test.

The mean leg length discrepancy in the study group was 3.8mm (range 1–9), compared with 9.8mm(range 0–17) in the control group (p=0.076). The mean torsional deformity in the study group was 7.7 degrees (range 20–2) compared with 9 degrees (range 0–22) in the control group (p=0.86). Within the navigated study group, length discrepancy was similar in subgroups A (3.6mm) and B (4.2mm). Torsion appeared more accurate in group B (5.6 degrees) than group A (8.7 degrees), although not significantly.

Computer navigation appears to improve leg length discrepancy following femoral nailing. Technique modification during the study improved rotational accuracy, and with further improvement, will make this technique applicable to femoral fracture fixation.

We analyzed the radiographic results of patients treated surgically for flatfoot deformity and who underwent medial cuneiform opening wedge osteotomy as part of the operative procedure. The aim of this study was to confirm the utility of the cuneiform osteotomy as part of the correction of hindfoot and ankle deformity. All patients requiring operative management of flatfoot deformity between January 2002 and December 2007 were prospectively entered in a database. We selected all patients who underwent medial cuneiform opening wedge osteotomy. We measured standardized and validated radiographic parameters on pre and post-operative weight bearing radiographs of the foot. All radiographs were assessed using the digital imaging software package (Siemens). The following measurements were used: lateral talus-1st metatarsal angle; medial cuneiform to floor distance (mm), talar declination angle, calcaneal-talar angle, calcaneal pitch angle, 1st metatarsal declination angle, talonavicular coverage angle, and anteroposterior talus-1st metatarsal angle. Other variables including concomitant surgical procedures, healing of the osteotomy, malunion, and adjacent joint arthritis were also noted. There were 86 patients with a mean age of 36 years (range 9–80). 15 patients had bilateral surgery. The aetiology of the deformity was flexible flat-foot in 48, rupture of the posterior tibial tendon in 41, rigid flatfoot deformity with a fixed forefoot supination deformity in 7, and fixed forefoot varus with metatarsus elevatus in 5. In addition to an opening wedge medial cuneiform osteotomy, a lateral column lengthening calcaneus osteotomy was performed in 80, a gastrocnemius recession in 76, a supramalleolar osteotomy in 2, a triple arthrodesis in 4, a subtalar arthroerisis in 13, excision of an accessory navicular in 6, a tendon transfer in 15 and medial-slide calcaneal osteotomy in 8 patients. The mean lateral talus-1st metatarsal angle improved from 23° to 1°; the mean medial cuneiform to floor distance improved from 20mm to 34mm; the mean talar declination angle improved from 39° to 27°; the mean calcaneal-talar angle improved from 64° to 55°; the calcaneal pitch angle improved from 14° to 23°; the mean 1st metatarsal declination angle improved from 17° to 26°; the mean talonavicular coverage angle improved from 45° to 18°; and the mean anteroposterior talus-1st metatarsal angle improved from 19° to 0° Radiographical analysis confirms that the medial cuneiform opening wedge osteotomy is a reliable and valuable surgical tool in the correction of the forefoot which is associated with flatfoot deformity and that arthrodesis of the 1st metatarsocuneiform joint may not be required to obtain correction of the elevated 1st metatarsal.

Compression staples are a popular form of fixation for osteotomy and arthrodesis. “Mechanical Compression” or “Shape Memory” designs are commercially available. We performed a biomechanical study to assess suitability for their intended functions.

Compression was measured using a load cell mounted within a simulated arthrodesis site. Two designs of mechanical compression and shape memory staples were tested and compared. The effect of altering the length of the staple limb was also assessed.

Both designs of mechanical compression staple had divergence of their fixation limbs causing inconsistent compression or even distraction. The shape memory staples all achieved a consistent compressive force at the fusion site. Staple limb length did not appear to alter the compression force generated.

The limbs of Mechanical Compression Staples splay open with a fulcrum at the intersection bridge. As a result, there is distraction of the far cortex and compression of the proximate cortex. Shape memory staples compress both the near and far cortices leading to stability and compression forces across the arthrodesis site.