Biocompatibility and toxicity of poly(vinyl alcohol)/N,O-carboxymethyl chitosan scaffold.

The in vivo biocompatibility and toxicity of PVA/NOCC scaffold were tested by comparing them with those of a biocompatible inert material HAM in a rat model. On Day 5, changes in the blood parameters of the PVA/NOCC-implanted rats were significantly higher than those of the control. The levels of potassium, creatinine, total protein, A/G, hemoglobulin, erythrocytes, WBC, and platelets were not significantly altered in the HAM-implanted rats, when compared with those in the control. On Day 10, an increase in potassium, urea, and GGT levels and a decrease in ALP, platelet, and eosinophil levels were noted in the PVA/NOCC-implanted rats, when compared with control. These changes were almost similar to those noted in the HAM-implanted rats, except for the unaltered potassium and increased neutrophil levels. On Day 15, the total protein, A/G, lymphocyte, monocyte, and eosinophil levels remained unaltered in the PVA/NOCC-implanted rats, whereas urea, A/G, WBC, lymphocyte, and monocyte levels remained unchanged in the HAM-implanted rats. Histology and immunohistochemistry analyses revealed inflammatory infiltration in the PVA/NOCC-implanted rats, but not in the HAM-implanted rats. Although a low toxic tissue response was observed in the PVA/NOCC-implanted rats, further studies are necessary to justify the use of this material in tissue engineering applications.

Platelet-rich plasma (PRP) enhances bone healing in non-united critical-sized defects: a preliminary study involving rabbit models.

INTRODUCTION: The use of bone grafts in treating non- or delayed unions as the result of large bone loss is well established. However, despite good outcomes, the time to achieve complete union is still considerably long. To overcome this problem, the use of platelet-rich plasma (PRP) has been advocated albeit with varying success. To determine the true effectiveness of PRP in treating non-/delayed unions, a study was conducted using (n=12) rabbit models. METHODS AND MATERIALS: Critical-sized defects measuring 2cm created in the midshaft of the right rabbit tibias were stabilised using 2.7-mm small fragment plates. A spacer placed in the defects to create a delay in bone union was replaced at 3 weeks with artificial bone grafts (Coragraft®), with or without PRP. The operated limbs were radiographed following the defect creation and at 3, 7 and 11 weeks (at sacrifice). Bone healing and histological changes were later assessed and scored using the appropriate grading systems. Four groups were compared for quality of healing: (group-A) control group, that is, no PRP or Coragraft; (group-B) PRP; (group-C) Coragraft; and (group-D) PRP and Coragraft. RESULTS: Group-D demonstrated the best bone healing based on radiological, histological and gross findings (Kruskall-Wallis: p<0.05). Group-C had significantly higher scores than group-B, whilst group-A had significantly lower scores than all other groups (Mann-Whitney U: p<0.05). CONCLUSION: The use of PRP with bone graft significantly improves the quality of bone healing. However, the use of PRP without bone substitute does not provide adequate repair tissue and, therefore, provides little benefit when used independently.

Mini open carpal tunnel release using Knifelight: evaluation of the safety and effectiveness of using a single wrist incision (cadaveric study).

This cadaveric study evaluates the margin of safety and technical efficacy of mini open carpal tunnel release performed using Knifelight (Stryker Instruments) through a transverse 1 cm wrist incision. A single investigator released 32 wrists in 17 cadavers. The wrists were then explored to assess the completeness of release and damage to vital structures including the superficial palmar arch, palmar cutaneous branch and recurrent branch of the median nerve. All the releases were complete and no injury to the median nerve and other structures were observed. The mean distance of the recurrent motor branch to the ligamentous divisions was 5.7 +/- 2.4 mm, superficial palmar arch was 8.7 +/- 3.1 mm and palmar cutaneous branch to the ligamentous division was 7.2 +/- 2.4 mm. The mean length of the transverse carpal ligament was 29.3 +/- 3.7 mm. Guyon's canal was preserved in all cases.

Midterm outcome of the Duracon total knee arthroplasty.

PURPOSE: To present midterm results of Duracon total knee arthroplasty (TKA) performed between 1991 and 2001. METHODS: One man and 43 women (65 knees) aged 46 to 84 (mean, 63) years who underwent primary TKAs using the Duracon prosthesis performed by a single surgeon were followed up for a mean of 8.5 (range, 5-11) years. All TKAs were cruciate-retaining and cemented, with only 9 of the patellae resurfaced. The diagnosis was osteoarthritis in 42 patients (61 knees), and rheumatoid arthritis in 2 patients (4 knees). Patients were assessed using the Knee Society Clinical Rating System, the Oxford Knee Score, and the Knee Society Total Knee Arthroplasty Roentgenographic Evaluation and Scoring System. RESULTS: The mean Knee Society knee score was 86 (range, 43-100) and the function score was 68 (0- 100). 94% of patients reported no or only mild pain. The mean Oxford Knee Score was 19. There was no patellofemoral complication, deep vein thrombosis or pulmonary embolism. Complications included a superficial infection and an uncontrolled deep infection. One patient had the insert exchanged for wear at the 11-year follow-up, and another had the polyethylene insert and tibial tray revised after a motorcycle accident. CONCLUSION: The Duracon TKA had good midterm clinical results with absence of patellofemoral complications.

Early results of prosthetic hip replacement for femoral neck fracture in active elderly patients.

PURPOSE: To evaluate the short-term clinical and functional outcomes of total hip arthroplasty performed for physiologically active elderly patients with Garden type-3 or -4 femoral neck fracture. METHODS: Records of 47 consecutive patients (40 female, 7 male) with type-3 or -4 femoral neck fracture (Garden classification) who underwent cemented total hip arthroplasty at our hospital during January 1999 to December 2002 were reviewed. Radiological and clinical (Harris functional hip score and Oxford hip score) assessments of 38 patients were measured with a mean follow-up period of 21 months (range, 4-48 months). RESULTS: The mean age of the 47 patients was 75 years (range, 62-89 years). Records of 9 patients were excluded because of death, lost to follow-up, and development of deep infection that necessitated implant removal and excision arthroplasty. The mean Harris hip score of the 38 patients was 83 (range, 59-97), whereas the mean Oxford hip score was 25.2 (range, 14-33). Pain in the hips was absent in 30 patients, 6 had slight pain occasionally, and 2 patients had mild-to-moderate hip discomfort. No signs of aseptic loosening or change in implant position were noted on radiographic assessment. Two cases of dislocation were reduced by closed reduction. Two patients had deep wound infection and were treated with debridement, implant removal, and conversion to girdle stone. CONCLUSION: This short-term study showed that total hip arthroplasty for femoral neck fracture had good postoperative results in functional hip and pain scores. More attention should be paid to coexisting medical illness (e.g. diabetes mellitus, hypertension, and ischaemic heart disease) and prevention of infection.

Total knee replacement subsequent to severe necrotising fasciitis of the lower limb.

The incidence of wound related complication following total knee arthroplasty is as high as 10%-20%. To perform total knee arthroplasty in a knee with extensive scarring around the knee can be a challenging task. We report a case of 55-year-old diabetic woman, who had total knee arthroplasty, performed two years after she had recovered from necrotizing fasciitis around the right knee. Understanding the vascular anatomy around the knee is of paramount importance in the planning of skin incision to ensure fewer wound related complications.

Midterm results of cemented Press Fit Condylar Sigma total knee arthroplasty system.

PURPOSE: To evaluate the midterm results of 50 patients who underwent total knee replacement using Press Fit Condylar (PFC) Sigma system. METHODS: We retrospectively reviewed 87 consecutive cases (50 patients with 37 bilateral cases) of PFC Sigma total knee replacement performed between January 1998 and December 1999. Patients were evaluated clinically and radiographically by an independent observer. The American Knee Society Score, Oxford Knee Score, and Knee Society radiographic assessment were used to rate knee function and to determine the satisfaction level of each patient. RESULTS: The mean age of the patients at the time of operation was 65 years (range, 41-85 years). The mean follow-up period was 5.4 years (range, 4.5-6.4 years). 44 patients (79 knees) were available for follow-up, 3 patients (3 knees) were lost to follow-up, and 3 patients (5 knees) died of unrelated causes. At the final follow-up, the mean Oxford Knee Score was 22. Using the American Knee Society Score, 88% of the knees were rated excellent, 4% good, 2% fair, and 6% poor. Five knees required revision surgery, the indications being infection in 4 knees and aseptic loosening in one knee. The survival rate of the implants was 94% at 6 years. CONCLUSION: The PFC Sigma total knee arthroplasty system has demonstrated good midterm results at our institution.

Revision of total hip arthroplasty using an anterior cortical window, extensive strut allografts, and an impaction graft: follow-up study.

PURPOSE: To report the outcome of revised total hip arthroplasty procedures involving an anterior cortical window, extensive strut allografts, and an Exeter impaction graft. METHOD: Eight patients (9 hips) with a mean age of 58 years underwent revision of total hip arthroplasty using the Exeter hip impaction graft system and strut allografts between 1995 and 1998. An extensile anterior approach was used, and an anterior cortical window was created in the femur, to remove the old implant. External strut allografts were attached by wires to provide cortical support. The mean follow-up duration was 74 months. Indications for surgery were aseptic loosening of previous implants in 8 hips and infection of one hip that had previously undergone total arthroplasty. RESULTS: 19 Dall Miles cables, 4 ordinary cerclage wires, and 8 cerclage wires tightened with the clincher knot technique were used to secure the allograft to the host bone. The strut grafts were found to be incorporated in all cases. No wires became loose. One patient developed 20 degrees of angulation at the allograft-host bone junction. Using the method of Fowler and Gie, we found that one femoral implant had subsided 2 mm within the cement mantle. Two other implants had 1 mm of subsidence at the cement bone interface, and one patient had a major subsidence of 15 mm that required revision. CONCLUSION: Using an anterior cortical window in the femur to remove the old implant does not predispose to failure of the allograft to incorporate into the host bone.

Small stem Exeter total hip replacement: clinical and radiological follow-up over a minimum of 2.5 years.

PURPOSE: To evaluate the clinical and radiological outcome in patients undergoing small stem Exeter total hip replacement. METHODS: A total of 46 small stem Exeter total hip replacements were performed on 44 consecutive patients (18 men and 26 women) attending the University of Malaya Medical Centre. The mean age at the time of operation was 58 years (range, 24-81 years). Of the 46 procedures performed, 35 were primary total hip replacements and 11 were revision operations, with aseptic loosening of the original implant being the main indication for revision. The main indications for surgery in primary cases were avascular necrosis and rheumatoid arthritis. Clinical and radiographic outcomes were assessed at 6 weeks', 12 weeks', 6 months' follow-up, and annually thereafter. Postoperative cementing technique was also assessed. RESULTS: The mean follow-up period was 4 years. The mean Oxford Hip Score improved from 46 points preoperatively to 17 points at the final follow-up examination. There were no revision operations, no implant breakages, and no excessive migration of the implants. The potential complications of implant failure due to smaller implant size and increased patient activity were not observed. CONCLUSION: Due to the smaller size of Asian femora, the small stem Exeter implant is a very useful development. This study suggests that it will perform as well as its larger counterparts.

Comparison of low-dose rofecoxib versus 1000 mg naproxen in patients with osteoarthritis. Results of two randomized treatment trials of six weeks duration.

OBJECTIVE: To compare the efficacy and safety of rofecoxib 12.5 mg once daily to naproxen 500 mg twice daily in patients > or = 40 years of age with knee or hip osteoarthritis (OA). METHOD: Two identical 6-week, randomized, double-blind studies were conducted (1 in Africa, Australia, Europe, Canada, Mexico, & South America; 1 in Asia). Primary endpoints were pain walking on a flat surface, patient global assessment of response to therapy, and investigator global assessment of disease status. RESULTS: Overall, 944 patients participated. For all efficacy endpoints, treatment effects for rofecoxib and naproxen were comparable and seen at the first measures of efficacy. Both compounds were generally well-tolerated, with an improved gastrointestinal safety profile for rofecoxib versus naproxen. CONCLUSIONS In these studies, rofecoxib 12.5 mg once daily (the lowest indicated dose) and naproxen 500 mg twice daily showed similar treatment effects in OA patients. Rofecoxib and naproxen were generally well tolerated.

The treatment of open tibial fractures and of tibial non-union with a novel external fixator.

We report the results of external fixation in 29 patients treated for tibial fractures and tibial non-union using a novel multi axial external fixator (MAXX) followed prospectively until bony union. The results of treatment were classified according to the Association for the Study and Application of the Method of Ilizarov (ASAMI). Overall, 13 patients had excellent bone results; 13 had good bone results; two had fair bone results, and 1 patient had poor bone results. Regarding functional results, 21 patients had excellent results; 6 obtained good results; none had fair results, and two had poor results. Acute patients did better functionally than chronic patients. This fixator is safe and versatile, although the indications for its use are very specific.

Selective thoracic fusion of King II scoliosis with segmental spinal instrumentation.

Segmental spinal instrumentation with Harrington rod secured to the spine by sublaminar wires was a popular method of scoliosis correction in 1980's. It was gradually replaced by newer rod-hook systems due to concern about neurological complications. However, correction of type II and III curves by selectively fusing the thoracic curves with these new instruments has resulted in poor results in some cases. The aim of this study is to review the result of selective thoracic fusion treated by segmental spinal instrumentation. Between January 1989 to October 1994, 31 patients with King II scoliosis were treated operatively in our unit. These consisted of 29 girls and 2 boys. The mean age of these patients were 11.3 years. The study population consisted of 21 Chinese, 5 Malays and 5 Indians. In one patient, the thoracic curve was convex to the left whilst the thoracic curves in the majority were to the right. The surgery was performed by three surgeons using harrington rods and posterior fusion with autograft. Anterior releases were also required in eight patients to increase flexibility. The curve correction obtained was an improvement from a average preoperative cobb's angle of 71.5 degrees to 39.5 degrees postoperatively. After an average follow-up period of 77.9 months, the correction deteriorated by 22% in the thoracic curve and 59% in the lumbar spine without disturbance to truncal balance. Only one sublaminar wire broke. However, no implant failure or removal has to be performed as yet. This technique appears useful in our institution with minimal morbidity.