Chee Ken Chan

Diluted povidone-iodine versus saline for dressing metal-skin interfaces in external fixation

Purpose. To compare infection rates associated with 2 dressing solutions for metal-skin interfaces. Methods. 60 patients who underwent distraction osteogenesis with external fixators were equally randomised into 2 dressing solution groups (diluted povidone-iodine vs. saline). Fixations were attained using either rigid stainless steel 5-mm diameter half pins or smooth stainless steel 1.8-mm diameter wires. Half-pin fixation had one metal-skin interface, whereas wire fixation had 2 interfaces. Patients were followed up every 2 weeks for 6 months. Results. Of all 788 metal-skin interfaces, 143 (18%) were infected: 72 (19%) of 371 in the diluted povidone-iodine group and 71 (17%) of 417 in the saline group. Dressing solution and patient age did not significantly affect infection rates. Half-pin fixation was more likely to become infected than wire fixation (25% vs 15%). Conclusion. Saline is as effective as diluted povidone-iodine as a dressing solution for metal-skin interfaces of external fixators. Saline is recommended in view of its easy availability and lower costs.

Revision Total Hip Arthroplasty Using an Acetabular Reinforcement Ring With a Hook: A Precise Follow-Up, at Average 11.4 Years, of a Previous Report

BACKGROUND This study aims at determining the average long-term result of revision total hip arthroplasty (THA) using the acetabular reinforcement ring with a hook (ARRH) and bone grafting in severe acetabular bony defect. Expected 15-year survival of ARRH in revision THA is included in the study. METHODS Retrospective review of 48 patients (48 hips) with follow-up duration of average 11.4 years (range, 6.1-21.4 years) was conducted. At each follow-up, Harris hip score was used to assess functional outcome, and radiographic acetabular component osteolysis was measured by DeLee and Charnley classification. Bone defects were assessed preoperatively and intraoperatively using American academy of orthopedic surgeons and Paprosky classification. The common modes of ARRH failures were evaluated. Bone consolidation, presence of heterotopic ossification, and complications such as infection and dislocation were recorded. RESULTS The bone defects were varied and included cavitary, segmental, and combined defects without any pelvic discontinuity. Mean Harris hip score improved from 52.6 points preoperatively to 82.0 points postoperatively. Nine acetabular revisions and 3 stem revisions (2 concurrent with acetabular revisions and 1 isolated stem revision) were performed. There were 5 infected cases and 1 patient with recurrent dislocation. The 11.4-year survival of revision THA with ARRH was 71% as the end point for acetabular revision surgery for any reason. The expected 15-year survival of revision THA with ARRH was 60%. The most common failure mode of ARRH was superomedial migration followed by lateral migration. CONCLUSION ARRH combined with bone grafting produces relatively good average long-term clinical results.

How Much Does the Anatomical Tibial Component Improve the Bony Coverage in Total Knee Arthroplasty

BACKGROUND Recently, anatomical designs in total knee arthroplasty are introduced to address asymmetry of the resected tibia cutting surface. It is still not well known how much improvement would be achieved in total knee arthroplasty, especially in Asian knees. METHODS We evaluated the bony coverage of 4 commercially available posterior-stabilized tibial designs (3 symmetrical: NexGen, Attune, and Vega; 1 anatomical: Persona) by measuring uncovered areas over 3 different regions: lateroposterior (LP), medioposterior (MP), and mediolateral (ML) areas. The implant size was chosen based on lateral anteroposterior dimension of the implant that most closely matched the corresponding surface of tibia. The knee with over coverage <1 mm and under coverage <2 mm was regarded as having optimal fit. RESULTS The optimal fit of anatomical design in LP dimension was achieved in 76% of the cases, which was not significantly different from other symmetrical designs (P > .05). The anatomical tibial implant had a more optimal fit in MP and ML dimensions (48% and 42%, respectively) compared to all symmetric designs (P < .05). All symmetrical tibial designs had significant absolute underhang in MP (62%-78%) and ML (24%-34%) areas without difference. The anatomical tibial design had significant improvement for posteromedial coverage by about 69.8%-74.3% compared with the symmetrical designs. CONCLUSION Recently introduced anatomical tibial design improves surface coverage at the medioposterior dimension in Asian knees. Moreover, there is small improvement in ML fit compared with the symmetrical designs.

Radiological analysis of the medial epicondyle in the adolescent throwing athlete.

INTRODUCTION Injuries to the medial structures of the elbow due to overhead throwing games are well documented. However, variations of medial epicondyles are not well described, especially in athletes with fused medial epicondyles. In this study, we evaluated variations in the medial epicondyle of baseball players who were aged 15-17 years and had fused epicondyles. METHODS In this cross-sectional observational study, 155 skeletally mature baseball players with unilateral medial elbow pain and 310 elbow radiographs were reviewed by two independent reviewers. The medial epicondyles were categorised into three groups: normal, elongated or separated. RESULTS Among the 155 patients, 65 (41.9%) had normal epicondyles, 41 (26.5%) had elongated epicondyles and 49 (31.6%) had separated epicondyles. The medial epicondyle was larger on the dominant arm for 125 (80.6%) patients; the mean surface area on the dominant arm was 222.50 ± 45.77 mm2, while that of the non-dominant arm was 189.14 ± 39.56 mm2 (p < 0.01). Among the three categories of medial epicondyles, separated epicondyles had the largest surface area, followed by elongated and normal epicondyles. CONCLUSION Medial epicondyles in adolescent throwing athletes can be categorised into three different groups according to their shape (normal, elongated and separated). We observed a correlation between the shape and the surface area of the medial epicondyle in adolescent throwing athletes, with separated medial epicondyles having the largest surface area. Further studies and follow-up are needed to determine the prognostic value and clinical significance of these morphological variations.

Necrotising Fasciitis of the Lower Limb caused by Community-Acquired Methicillin-Resistant Staphylococcus aureus

Necrotising fasciitis caused by Community-Acquired Methicillin-resistant Staphylococcus aureus (CA-MRSA) has emerged as a new entity. Although it is recognised worldwide, there have been no reported cases to date in Malaysia. We report a case of necrotising fasciitis of the left lower limb in an otherwise healthy 20-year-old man. He presented with septic shock and despite the paucity of clinical signs in the limb, the infection was aggressive. Methicillin-Resistant Staphylococcus aureus (MRSA) was isolated from the deep fascia of the leg. Panton-Valentine leucocidin gene (PVL), which is a stable genetic marker for CA-MRSA strain, was positive in this case. This case of community acquired MRSA necrotising fasciitis is of concern and may herald the emergence of this resistant organism in Malaysia. Vigilant surveillance and microbiological monitoring is needed to follow this CAMRSA trend.

Incorporation of Human-Platelet-Derived Growth Factor-BB Encapsulated Poly(lactic-co-glycolic acid) Microspheres into 3D CORAGRAF Enhances Osteogenic Differentiation of Mesenchymal Stromal Cells

Tissue engineering aims to generate or facilitate regrowth or healing of damaged tissues by applying a combination of biomaterials, cells, and bioactive signaling molecules. In this regard, growth factors clearly play important roles in regulating cellular fate. However, uncontrolled release of growth factors has been demonstrated to produce severe side effects on the surrounding tissues. In this study, poly(lactic-co-glycolic acid) (PLGA) microspheres (MS) incorporated three-dimensional (3D) CORAGRAF scaffolds were engineered to achieve controlled release of platelet-derived growth factor-BB (PDGF-BB) for the differentiation of stem cells within the 3D polymer network. Fourier transform infrared spectroscopy, energy-dispersive X-ray spectroscopy, scanning electron microscopy, and microtomography were applied to characterize the fabricated scaffolds. In vitro study revealed that the CORAGRAF-PLGA-PDGF-BB scaffold system enhanced the release of PDGF-BB for the regulation of cell behavior. Stromal cell attachment, viability, release of osteogenic differentiation markers such as osteocalcin, and upregulation of osteogenic gene expression exhibited positive response. Overall, the developed scaffold system was noted to support rapid cell expansion and differentiation of stromal cells into osteogenic cells in vitro for bone tissue engineering applications.

Multicentric Disappearing Bone Disease treated with Arthroplasty

Multicentric disappearing bone disease, or Gorham disease, is a rare entity. A middle age woman, presented to us with left sided antalgic gait and severe bony deformity of her left knee. Radiograph revealed massive bone defect of the medial condyle of the left tibia with subluxation of the knee joint. She was scheduled for knee replacement in six months. However, she developed another lesion over the right hip that typically mimicked the disease progression of disappearing bone disease. The right femoral head vanished progressively within three months without significant history of infection or trauma. Subsequent bone biopsy of the right femoral head and left tibia condyle confirmed the diagnosis. Total knee replacement was carried out for her left knee. She remained pain free on her left knee. A year later, after confirming by sequential radiographs that the osteolysis had stopped, total right hip replacement was performed. Five years later, she remained pain free and both the arthroplasties were stable.

Ipsilateral femoral fracture non-union and delayed union treated by hybrid plate nail fixation and vascularized fibula bone grafting: a case report.

Non-union is a well recognized complication of femoral neck fractures. The decision whether to attempt fracture fixation or to resort to hip replacement is particularly difficult in patients in the borderline age group in whom complex attempts at gaining union may fail and later present a difficult revision. On the other hand the patient may be young enough that arthroplasty best be avoided . Besides, presence of ipsilateral femoral shaft fracture with delayed union in addition to the femoral neck non-union will pose major problems at operation. We share our experience in treating a femoral neck fracture non-union with ipsilateral femoral shaft delayed union in the shaft and in the distal femur in a fifty years old patient. The fracture was treated with an angle blade plate and supracondylar nail supplemented with a free vascularised fibular bone grafting and autologous cancellous graft. There was radiological union at fourth month. At sixth months, the patient was free of pain and able to walk without support. Thus, we would like to suggest that vascularised fibula bone grafting with supracondylar nailing is a viable option for this pattern of fracture. Key Words Vascularized fibular bone graft, neck of femur, femoral shaft fracture, non-union

Femoral Shaft Cortical Pathology associated with longterm Alendronate Therapy: A New Classification.

Abstract There are reported cases of cortical reaction over the tension side of the normal femoral shafts in patients on long term treatment with alendronate, leading to subsequent femoral shaft fractures. We performed a retrospective review of patients with low-energy femoral shaft fracture on alendronate, admitted to our institution during the period 2004 to May 2009. The presence of radiological changes of cortical hypertrophy with or without Looser’s zone over the tension side of the femoral bone (normal limb) was determined and correlated with clinical symptoms. Thirteen patients were identified. Average duration of alendronate use was 6.5 ± 3.3 years (ranges, two to 10 years). These radiological changes were noted in four patients. Average duration of alendronate usage in these four patients was 6.5 ± 2.4 years (ranges, 5 to10 years). Prodromal thigh pain was present in a patient, who had cortical hypertrophy with the presence of a Looser’s zone traversing the cortex on the femoral shaft. One patient had Looser’s zone limited at the lateral hypertrophied cortex without prodromal pain. The interobserver kappa coefficient was 0.96. A femoral radiograph should be performed in all patients who are on long-term alendronate therapy who present with thigh pain. We propose a new grading system based on our observation of the radiological features in these four cases. This new grading of the radiological spectrum of femoral shaft cortical pathology has the potential to stratify the risk of low energy femoral fracture for patients treated with long-term alendronate therapy. Key Words Femur, Cortical Hypertrophy, Looser Zone, Alendronate

Staged Surgery for Severe Soft Tissue and Bone Loss of the Knee

A 20- year-old female student was involved in a motor vehicle accident. She sustained a severe friction injury to the left knee that resulted in considerable soft tissue and bone loss. There was also damage to the knee extensor mechanism, tibialis anterior muscle, femoral trochlea, the anterior half of the tibial plateau extending distally to the proximal tibia and skin. However, there was no crushing of the limb or resultant neurovascular deficit but cancellous bone and the remainder of the joint were exposed. Repeated surgical debridement was performed and was followed by covering of the soft tissue using a latissimus dorsi free flap and skin grafts. The bony defect was reconstituted with antibiotic bone cement to prevent flap adherence and shrinkage, enhance stability and prevent fracture. The cement was later removed at the time of arthrodesis at which time an ipsilateral double barrel vascularised fibular graft supplemented with autogenously cancellous bone and a ring fixator was used. Computer tomography confirmed union at three months post procedure. The fixator was then removed and a tibialis posterior transfer was performed.