Does stress shielding occur with the use of long-stem prosthesis in total knee arthroplasty?

A retrospective study conducted to evaluate the possible occurrence of stress shielding with the use of long-stem tibial prosthesis in total knee arthroplasty. Forty-one patients were reviewed (twenty-three standard prosthesis, eighteen long-stem prosthesis) and forty-one unoperated knee of the contralateral limb). Patients underwent bone mineral density assessment with a dual-energy X-ray absorptiometry (DEXA) bone densitometer for the hip and bilateral knees. The mean time interval between surgery and the DEXA assessment was 87.7 months. There was no significant statistical difference (P > 0.05) in the bone mineral density patterns of the tibia with the use of either standard or long-stem prosthesis. The utilization of the long-stem prosthesis to off-load the tibia is not associated with any significant bone mineral density changes or stress shielding.

Changes in the levels of major cardiovascular risk factors in the multi-ethnic population in Singapore after 12 years of a national non-communicable disease intervention programme.

INTRODUCTION: The National Healthy Lifestyle Programme, a population-wide non-communicable disease intervention programme, was started in 1992. A National Health Survey is carried out every six years to evaluate the impact of this programme on the cardiovascular risk factor profile of the resident population of Singapore. METHODS: The 2004 National Health Survey (NHS 04) was a population-based survey carried out over a period of four months from September to December 2004. A combination of disproportionate stratified sampling and systematic sampling was used to select a representative sample (n=7,078) for the survey. The reference population comprised 2.4 million multi-racial Singaporeans aged 18-69 years. Anthropometric and blood pressure measurements were carried out on all subjects and blood samples were taken for biochemical analysis. The results were compared with those of a similar survey conducted in 1998. RESULTS: A total of 4,084 Singapore residents took part in the survey, giving a response rate of 57.7 percent. The age-standardised prevalence of hypertension (greater than or equal to 140/90 mmHg) in Singapore residents aged 30-69 years decreased from 28.0 percent in 1998 to 24.0 percent (p-value is less than 0.001) in 2004. The prevalence of high total cholesterol (greater than or equal to 6.2 mmol/L) among those aged 18-69 years fell from 26.0 percent in 1998 to 18.1 percent (p-value is less than 0.001) in 2004. The prevalence of diabetes mellitus in residents aged 18-69 years in 2004 was 7.8 percent, compared to the 1998 level of 9.5 percent (p-value is less than 0.01). The level of obesity (body mass index is greater than or equal to 30 kg/sqm) increased slightly from 6.2 percent in 1998 to 6.8 percent (p-value equals 0.1627). The prevalence of daily smoking decreased from 15.0 percent in 1998 to 12.5 percent in 2004 (p-value is less than 0.001), while that of regular exercise increased from 17.0 percent to 25.0 percent (p-value is less than 0.001). Ethnic differences in the prevalence of diabetes mellitus, hypertension, hypercholesterolaemia, and exercise were observed. CONCLUSION: The NHS 04 results suggest that the National Healthy Lifestyle Programme significantly decreased daily smoking, high blood cholesterol and hypertension, and increased regular exercise over 1998 levels. The results also suggest that the programme stabilised the prevalence of obesity and diabetes mellitus.

The natural history of spontaneous osteonecrosis of the medial tibial plateau.

The natural history of spontaneous osteonecrosis of the medial tibial plateau remains controversial and incomplete. We have studied 21 patients (aged between 53 and 77 years) with clinical and scintigraphic features of spontaneous osteonecrosis of the medial tibial plateau who were observed prospectively for at least three years (37 months to 8.5 years). The mean duration of follow-up was 5.6 years. The mean duration of symptoms at presentation was 4.7 weeks (3 days to 12 weeks). Radiographs of the affected knee at the first visit were normal in 15 patients and mildly arthritic in six. The characteristic radiographic lesion of osteonecrosis was noted at presentation in five of the mildly arthritic knees and during the evolution of the disease in eight of the radiographically normal knees. During the follow-up, subchondral sclerosis of the affected medial tibial plateau was noted in 16 knees. There are three distinct patterns of outcome: 1) acute extensive collapse of the medial tibial plateau in two knees within three months of onset; 2) rapid progression to varying degrees of osteoarthritis in 12 knees, in eight within a year, in all within two years and deterioration of the pre-existing osteoarthritis in three; and 3) complete resolution in four knees, two of which were normal at presentation and two mildly osteoarthritic. The two patients with acute extensive collapse and three who had rapid progression to severe osteoarthritis required total knee arthroplasty. We conclude that osteonecrosis of the medial tibial plateau progresses in most cases to significant degenerative disease of the knee.

History of the orthopaedic specialty in Singapore.

The Orthopaedic specialty service in Singapore began in 1952 with the appointment of J A P Cameron to the chair of Orthopaedics at the University of Malaya and the simultaneous establishment of the Department of Orthopaedic Surgery at the General Hospital, Singapore. A second department--a government department of orthopaedic surgery was established in 1959, under the headship of Mr D W C Gawne also at the General Hospital, Singapore to cater to the increasing workload. Although orthopaedic services were already available at Alexandra Hospital, Tan Tock Seng Hospital and Toa Payoh Hospital from as early as 1974, the formal establishment of a Department of Orthopaedic Surgery in these hospitals took place only in 1977. The pioneering local orthopaedic surgeons--Mr W G S Fung, Mr K H Yeoh, and Mr V K Pillay--joined the orthopaedic service in 1961. In 1967, Prof Pillay and Mr Fung took the leadership role at the University Orthopaedic Department and Government Orthopaedic Department, General Hospital, Singapore, respectively. Subspecialty services in orthopaedic surgery began in the late 1970s, and currently, at least 7 subspecialties have developed to divisional status at one or more hospitals. In 2001, there were 92 registered Orthopaedic specialists and just over a third were in private practice.

The growth and development of orthopaedic sports medicine in Singapore.

Orthopaedic sports medicine is currently a well established subspecialty of orthopaedic surgery in Singapore. It had its beginnings in the late 1960s and has since grown to be one of the major orthopaedic subspecialties. Knee, shoulder and ankle injuries constitute the majority of cases seen by the orthopaedic sports medicine specialists. Significant scientific contributions to the international literature have been made by our specialists over the years. Today, Singapore is a regional hub for the provision of orthopaedic sports medicine care and training.

Extremity osteosarcoma--a Southeast Asian experience.

INTRODUCTION: We present our experience with limb salvage emphasising the use of vascularised bone grafts in combination with autoclaved tumour bone for limb salvage in osteosarcoma. MATERIALS AND METHODS: Thirty-six cases with extremity osteosarcoma, all of which were managed at a single institution between 1980 and 1999, were reviewed at a mean follow-up of 9 years (range, 10 months to 200 months). There were 26 patients who underwent limb salvage surgery and 10 patients who had amputation. RESULTS: In the limb salvage group, 12 bone defects were bridged using vascularised bone grafts alone while autoclaved tumour bone was used for reconstruction in the remaining 14 patients. In these 14, there were 10 with autoclaved tumour bone and vascularised bone, 2 with autoclaved bone and non-vascularised bone and 2 with autoclaved bone alone. The joint was preserved in 13 of the 26 reconstructions. Of these, 11 involved preservation of the knee joint contributing to a quantum gain in function with 84% good and excellent results. The actuarial survival was 64% at 2 years and 48% at 5 years, with no significant difference between ablation and limb salvage. CONCLUSION: The use of the autoclaved bone provided yet another effective alternative for bridging large defects following resection of high grade tumours.

The anatomy of the anterior origin of the deltoid.

We studied the origin of the anterior deltoid from the lateral third of the clavicle and the leading anterior edge of the acromion in 18 cadaver shoulders by anatomical and histological methods. The main origin of the deltoid was from the superior surface of the anterior acromion, but muscle and tendinous attachments were also seen on the entire anterior surface of the acromion, its anteroinferior surface and on the whole width of the anterior surface of the clavicle. Mock arthroscopic acromioplasty was shown to detach deltoid fibres from the anterior surfaces, leaving the superior attachment in continuity. Potentially, arthroscopic subacromial and clavicular resection can detach deltoid fibres originating from the anterior and anteroinferior surfaces of the acromion and clavicle and thus weaken the anterior deltoid.

The Brunelli reversed flow pedicle flap from the thumb.

A reversed flow pedicle flap based on the dorsoulnar collateral vascular supply to the thumb, originally described by F. Brunelli, was used to cover a large volar defect of the little finger. The versatility of the flap, the possibility of innervation, and minimal donor-site morbidity give it advantages over the simple cross-finger and even the innervated cross-finger flaps.

Arthroscopy of the knee.

Arthroscopy of the knee was first performed early this century. However, it became generally accepted and grew to be a major contributor to orthopaedic surgery only during the last two decades. It has improved our understanding of numerous knee pathologies and allowed us to treat many of these disorders with considerably less morbidity. But there remain areas that warrant attention. Training in arthroscopic technique needs to be intensified and our knowledge of knee conditions should be improved if we are to avoid certain pitfalls and complications during arthroscopic surgery. Another issue that must be addressed is the inappropriate use and abuses of arthroscopic surgery of the knee. Improved audit, that insist on photographic documentation of the lesion before and after treatment is suggested to curb this latter problem.

Infection of vascularized fibular grafts.

Between June 1978 and July 1991, 64 limb reconstructions were done using vascularized fibular grafts. Of these, 10 became infected. Five grafts were proven viable, whereas the other 5 were proven nonviable based on the survival of the skin in the composite osteocutaneous graft and from bone scans, angiograms, and biopsies. A distinct difference in the radiologic manifestation and clinical course of the infection was noted between the viable grafts and nonviable grafts. The viable grafts showed radiologic changes of osteomyelitis that were localized, and the graft incorporated, healed with antibiotics, and exhibited graft hypertrophy. In the nonviable grafts, the radiologic changes were extensive, evidence that resorption of the grafts had resulted. This suggests that, because of the poor prognosis associated with infection of the nonviable vascularized fibular grafts, the infected grafts should be removed early to minimize the morbidity and to shorten the protracted course associated with infection. With the infected viable grafts, efforts at salvaging the graft with multiple debridements and systemic antibiotics were rewarding.

Surgical management of osteochondral fractures of the phalanges and metacarpals: a surgical technique.

We report a technique of reducing and stabilizing osteochondral fractures of the metacarpals and phalanges, using the principle that the space within a joint is only "potential." Accurate reduction of the fragment and accurate approximation of the capsular rent effectively traps and holds the fragment without the need for internal fixation. Preservation of all soft tissue attachment to the fragments and early supervised mobilization ensure healing of both the bony and hyaline cartilage components.

Post-traumatic differential osteoporosis of the patella.

The differential density developing after patella fractures between the proximal and distal poles has been attributed to avascular necrosis of the proximal fragment. Six cases are presented here where differential densities between the proximal and distal poles developed after trauma to the patella or knee. Based on the natural history of the condition, the rapidity of onset of the differential densities, osteoporosis of the whole patella later and complete resolution of the changes finally, we postulate that this phenomenon is due to a differential rate of osteoporosis of the proximal and distal parts of the patella because of the differences in their blood supply and not because of avascular necrosis of the proximal pole.

Arthroscopic retrieval of loose bodies.

Using an ordinary metallic suction tube through a separate puncture wound, we were able to retrieve a free-floating loose body by suction action. We facilitated its retrieval by using conveniently located grasping forceps. This combination reproduces the action of commercially available suction loose body forceps.

Single-blind comparative analgesic and safety study of single doses of intramuscularly administered ketorolac tromethamine and pethidine hydrochloride in patients with pain following orthopaedic surgery.

Ketorolac tromethamine, a potent non-narcotic prostaglandin synthetase inhibiting analgesic was compared with pethidine for relief of moderate to severe postoperative pain. Forty-eight patients received Ketorolac 0.5 mg/kg and 52 received pethidine 1.25 mg/kg. The degree of pain prior to the administration of the drug and pain relief that followed were quantified using a vertical visual analogue scale (VAS) and monitored at hourly intervals. The safety profile was also studied by recording all adverse events noted. The mean pain (VAS) score at medication for Ketorolac was 7.04 and for pethidine 7.09. The pain relief obtained in the first four hours following administration of the drugs was similar for pethidine and Ketorolac. Although Ketorolac showed a longer sustained pain relief, time to peak analgesia after administration of this drug was slower than that after pethidine. It took 30 to 50 min for pethidine compared to 75 to 150 min for Ketorolac to achieve peak analgesia. The latter is therefore inappropriate if rapid pain relief is required. The incidence of side effects was significantly greater with pethidine (40.4%) as compared to Ketorolac (10.4%). The similar analgesic efficacy to pethidine makes Ketorolac an appropriate drug for the relief of postoperative pain especially in day surgery settings where observation following administration of the drug as in the case of pethidine can be dispensed with and patients sent home earlier because of the minimal side effects associated with its use. Caution must be exercised with the use of large doses of Ketorolac especially if the drug is used for more than 5 days to avoid serious complications like renal failure and gastrointestinal bleeding.

Reactivation of rheumatoid arthritis in knees following total knee replacement.

Between May 1985 and December 1990, 20 patients with rheumatoid arthritis had 34 total knee replacements performed. The mean follow-up period was 4.1 years and the range was 2.3 to 7.8 years. Five knees with total knee replacements (74.7%) in 4 patients were affected by activation of the rheumatoid process at an average postoperative interval of 28.6 months while the other 29 knees with total knee replacements (85.3%) remained in remission. Factors that appeared to have an influence on post total knee replacement rheumatoid activation included the activity of the disease preoperatively, and whether synovectomy was undertaken at surgery. Whether patella replacement was undertaken appeared not to have influenced postoperative reactivation of the disease. Using the Hospital for Special Surgery Knee score, total knee replacement in our cases gave excellent results. The complications included one knee with dislocation of the patella and another with infection.

The A-O femoral distractor for ankle arthroscopy.

Arthroscopy of the ankle is a well established technique for the evaluation of ankle pain or dysfunction. Using the A-O femoral distractor with pins in the distal tibia and calcaneum, respectively, we were able to provide distraction for easy visualization and operative manipulation within the ankle joint comparable with that obtained with commercially available ankle distractors.