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Biomedical subjects

L K Hung

Publications and source records attributed to L K Hung.

At least 37 records · Page 2Linked to original sources

Current treatment of ganglion of the wrist.

Ganglion of the wrist is one of the the most common lesions of the hand. The cause of pain in an occult dorsal wrist ganglion has been linked to compression of the posterior interosseous nerve at the wrist. A case is presented in this paper and the pathoanatomy discussed. Ultrasound-guided aspiration after hyaluronidase instillation provided a useful alternative to surgery with a high success rate. Arthroscopic decompression for dorsal and palmar wrist ganglia offered the patient the benefit of smaller surgical scars and a high success rate. A description of the surgical techniques, pathoanatomy, and early results of the authors and a review of the literature is presented.

Accidental Falls↗

Uncommon hand tumours.

This paper presented clinical examples of some rare or uncommon presentations of tumours of the hand, including glomus tumour, intraosseous dermoid, fibrolipoma of the radial nerve, blastomycotic cyst and synovial sarcoma. Each lesion is illustrated by review of case histories, radiological and pathological features.

Adult↗

A histomorphometric observation of flows in cortical bone under dynamic loading.

Ferritin was used as a histological marker for interstitial fluid flows in four goats. Two transcortical pins were inserted into each tibia mediolaterally-one at the proximal side and one at the distal side of the diaphysis. For the experimental limb, dynamic loading was applied to the pins on the lateral side. The contralateral limb was used as control. Ferritin was injected into the nutrient arteries feeding the two tibiae. The goat was then euthanized immediately. Undecalcified slides of the tibial cortical bone from both the experimental and the control limbs were studied histologically. Percentages of Haversian systems marked with ferritin halos and the average radial distance of ferritin transudation away from the Haversian canals were assessed. Results for the medial and lateral sides of both the experimental and control tibiae were reported. Significant differences in the ferritin transudation distance were found between the experimental and the control tibia (P < 0.005) and between the medial and the lateral sectors (P < 0.05). The approach documented in this paper could be used to address systematically how external loading might affect the transport phenomena in cortical bone.

Animals↗

Alteration of patellofemoral contact during healing of canine patellar tendon after removal of its central third.

Alterations of the patellofemoral (PF) contact pressure and area were assessed using pressure-sensitive film after the removal of the central third of patellar tendon (PT) with healing over time in twelve dogs. The contralateral knee served as control. Histological sections were prepared for descriptive evaluation. No alterations in PT strain, PF contact pressure and area were measured immediately after the removal of the central third of PT compared with that before its removal. Compared with contralateral control, the healing of the donor PF induced a significantly increased PF contact area but not PF contact pressure in the specimens harvested at 6, 12, and 18 months after operation. Increased PF contact area indicated a proximal shift of the PF joint contact during flexion, which was associated with an increased strain of the healing PT under loading. The healing PT became hypertrophic compared with control, but the differences in the cross-sectional area were reduced over time. Histologically, a poorly organized extracellular matrix was observed at 6 months, with a progressive improvement in collagen fiber alignment up to 18 months postoperatively. The results of this study suggest that the removal of the central third of PT does not immediately change PF contact pressure and areas. However, remodeling of the healing tendon may cause an elongated PT, resulting in an increase in PF contact area under a given quadriceps force by knee extension.

Animals↗

Removal of the lateral or medial third of patellar tendon alters the patellofemoral contact pressure and area: an in vitro experimental study in dogs.

OBJECTIVES: To compare patellofemoral contact pressure and areas after immediate removal of the lateral, central, or medial third of patellar tendon. DESIGN: In vitro experiment in 12 dogs. BACKGROUND: Alteration of the vector sum of the quadriceps muscle contraction after removal of partial patellar tendon might result in changes of patellar tracking in the trochlea. METHODS: Patellofemoral contact pressure and areas were recorded using Fuji pressure-sensitive film at 45 degrees, 60 degrees, and 90 degrees of knee flexion under an isometric quadriceps force of 100% body weight. The patellofemoral contact imprint from the intact knees were obtained as control, and the lateral (n=4), central (n=4), and medial (n=4) third of the patellar tendon were subsequently removed and the patellofemoral contact imprint was recorded. RESULTS: The patellofemoral contact area was found to increase with increasing knee flexion angles. No change in patellofemoral contact pressure and areas was found after removal of the central third patellar tendon. However, after removal of either lateral or medial third of patellar tendon, the patellofemoral contact was rotated with increasing knee flexion angles. This was due to the altered vector sum of the quadriceps force, resulting in significantly decreased patellofemoral contact areas and simultaneously a significantly increased contact pressure, characterized with concentration of patellofemoral contact pressure on both lateral and medial facets of the patellofemoral joint. CONCLUSIONS: The results suggest that removal of the central third of patellar tendon may not alter the patellofemoral contact pressure and areas as compared with removal of either lateral or medial third of patellar tendon that may result in an altered postoperative tracking mechanism of the patellofemoral joint immediately after operation. RELEVANCE: Findings of this in vitro animal study supports the use of central third of patellar tendon as autograft for anterior cruciate ligament reconstruction. However, further experimental studies are needed to investigate how the postoperative healing of the host patellar tendon will influence the findings obtained from this in vitro study.

Animals↗

Histomorphological study on pattern of fluid movement in cortical bone in goats.

Streaming potential is considered one of the most important mechanisms to moderate the function of osteoblasts and osteocytes in bone growth, remodeling and fracture repair. The present study was designed to demonstrate the fluid flow pattern in the cortical bone matrix in an animal model using undecalcified histological techniques. Immediately after injection of ferritin into the tibia nutrient artery of four adult goats, the animals were euthanized. Undecalcified transverse and longitudinal blocks of cortical bone obtained from the tibial diaphysis were immersed in Perl's reagent and embedded in methyl methacrylate. Sections were cut and ground to 30-50 microm thickness for histomorphological evaluation at different magnifications and focusing levels. A serial grinding technique was used to validate the observations made at different focusing levels. As expected, ferritin was observed in the interstitial compartment in both transverse and longitudinal sections. In osteons sectioned transversely, the pattern of centrifugal movement of ferritin marker was demonstrated as single or multiple halos around the Haversian canal. The most apparent halo in osteons with multiple halos was the one found closest to the Haversian canal. The total number of identifiable single or multiple halos increased or was altered when counting was made with higher magnification or at different focusing levels, respectively. Irregular and incomplete ferritin halos indicated structural complexity of the osteons. Overall, the pattern of ferritin movement was consistent with bulk interstitial fluid flow influenced by both hydrostatic pressure and transudation. This study demonstrated for the first time multiple concentric halos of the fluid flow marker ferritin around Haversian canals in the cortical interstitial compartment. The results suggest that the undecalcified technique might be a useful method for qualitative and quantitative studies on cortical fluid flow.

Animals↗

Impairment of hand function and loss of earning capacity after occupational hand injury: prospective cohort study.

OBJECTIVE: To examine the loss of earning capacity and permanent impairment of a cohort of male patients who had experienced finger amputation due to occupational injury. DESIGN: Prospective cohort study. SETTING: University teaching hospital, Hong Kong. PATIENTS: Twenty-eight male patients aged 26 to 55 years who presented with work-related finger amputations in their dominant right hand from 1990 through 1991. MAIN OUTCOME MEASURES: Type and extent of amputation, and hand function before and after (mean, 11 months; range, 8-6 months) the patients' return to work. Assessment results were compared with patients' percentage loss of earning capacity as calculated using the scale described in the Employees' Compensation Ordinance of Hong Kong. RESULTS: Patients with injuries that corresponded to a loss of earning capacity of 12% or greater had a significant impairment in their hand function (P<0.05); the hand function of this group after their return to work significantly improved (P<0.05). There were no significant differences between the loss of earning capacity scores as calculated by the Hong Kong, American Medical Association, or Indian Medical Association scales. CONCLUSION: Patients whose loss of earning capacity of 12% or greater are likely to have significant long-term impairments of hand function. Thus, a more intensive rehabilitation programme should be provided to this group.

Journal Article↗

Lengthening of a one-bone forearm. A sequel of neonatal osteomyelitis.

An 8-year-old girl presented with marked shortening of the right forearm due to destruction of both the radius and ulna secondary to neonatal osteomyelitis. A one-bone forearm operation was performed to achieve a stable forearm. Two years later, the one-bone forearm was lengthened for 6 months by callus distraction (callotasis) achieving 12 cm of extra length. The patient was last followed up at the age of 16. The appearance and functional outcome of the right upper limb had been improved and she was independent in all activities of daily living.

Child↗

A longitudinal study of C3, C3d and factor Ba in burn patients in Hong Kong Chinese.

A longitudinal study of serum C3, C3d and fragment Ba was carried out in 53 burn patients of Chinese origin whose total burn surface area ranged from I to 45%. Complement C3 was found to be activated on or before day 7 post-burn. The sharp increase in C3d suggested an acute inflammatory response. In addition factor Ba was increased in these patients, suggesting that the alternative pathway was also activated following thermal injuries. The fluctuations of C3, C3d and Factor Ba observed about 1 year after injury suggested chronic inflammation associated with long term of outcome of healing in the burn sites.

Adult↗

Vascularized bone grafts in the treatment of juxta-articular giant-cell tumors of the bone.

The clinical results of vascularized bone grafts in 39 patients with giant-cell tumor affecting the extremity were evaluated. The sites involved were the proximal tibia (8), proximal femur (4), calcaneus (1), proximal humerus (8), and distal radius (18). Osteoarticular replacement was performed in patients with giant-cell tumor involving the radius; in 15 of these, a suitably tailored vascularized iliac crest graft was used, and in the remaining three, the fibula was used. Follow-up ranged from 2 to 7 years, with an average of 3.3 years. Clinical results were judged on the basis of functional and radiologic evaluations. Reconstructions involving the distal radius were evaluated separately from the rest of the juxta-articular grafts. Excellent results in 17 and good results in three of the juxta-articular grafts were observed. Eighteen patients with the distal radius affected were followed-up for periods ranging from 2 to 12 years. Non-union was seen in one, carpal subluxation in five, and spontaneous radiocarpal fusion in one patient. A pain-free functional wrist was retained in 17 of these 18 patients. Three local recurrences were observed (2.5 percent). The vascularized bone graft provided a good biological and mechanical support to the subchondral bone and overlying articular cartilage. Satisfactory reconstruction was thus possible following wide resection, without sacrificing joint function and with gratifying oncologic results. The use of a suitably tailored block of vascularized iliac crest is an acceptable method to preserve wrist and radio-ulnar joint motion, following excision of the distal radius affected by a giant-cell neoplasm.

Adult↗

Multiple chop wounds in Hong Kong. An epidemiological study of an unusual injury.

Knife injuries can be classified into stabbing injuries and multiple laceration or multiple chops, the latter being much more common in Chinese communities. It is the mark of criminal gang attacks with their tendency to use long knives and choppers rather than guns. The intention is often to wound rather than kill. A survey of 89 cases revealed that 90% of the victims are men, with a mean age of 27 years; 75% was admitted to the hospital at night, and in 78% of the cases the assailants were persons unknown, or so we were told by the victims. The reasons for the attacks were also not given. Most of the women victims were assaulted by their spouse. Some 74% of the patients suffered three to six lacerations; 62% of the injuries were on the extensor surfaces of the upper limbs, while the hand and the back of the trunk were also common sites. The type of management differs from that for stabbing injuries. There were no fatalities, and less than half of the patients required blood transfusion. The average hospital stay was 6.2 days. The morbidity of these injuries involves damaged tendons and nerves.

Adult↗

The cutometer and ultrasonography in the assessment of postburn hypertrophic scar--a preliminary study.

Sixteen patients with various degrees of postburn hypertrophic scars were evaluated by ultrasonography and elastometry. An Aloka Echo Camera (SSD-500) with a 7.5 MHz probe and a Cutometer SEM 575 skin elastometer were used. Serial monthly examinations were performed using both pieces of equipment. In some patients, more than one scar was assessed. The assessments were correlated with clinical grading of the progress of the scars. It was noted that ultrasonography was very sensitive in the localization of scar tissues, distinguishing them from normal skin, assessment of thickness and also delineation of the extent of scar tissues. The subcutaneous part of the scar could be assessed. Cutometer SEM 575 is a new machine that applies a gentle suction to the skin to measure its viscoelasticity. It is sensitive, the inter-observer variation is low, and it could be used for the grading of a scar. These two assessment techniques compliment other methods of scar assessment and will prove useful when assessment of response to treatment is required.

Adult↗

Delivery of medication by iontophoresis to treat post-burn hypertrophic scars: investigation of a new electronic technique.

At present, direct current (DC) and pulsed direct current (PDC) methods are used for iontophoresis. Although the DC field has high efficiency, it exhibits some side-effects. The PDC field has little side-effects, but the efficiency is lower. In this study, a new iontophoretic drug device was designed for providing the maximal efficiency with the minimal side-effects. Tests of animal and human models showed that the permeation rate of the new field was higher than that of PDC and DC fields, and side-effects were lower than that of the DC field.

Administration, Cutaneous↗

Recent changes in the pattern of hand injuries in Hong Kong: a regional hospital survey.

Adult inpatients with injuries to the hand admitted to the Department of Orthopaedics and Traumatology of the Prince of Wales Hospital, Hong Kong, from June 1992 to May 1993 were surveyed (n=533). The causes of injury, mechanisms involved, and the nature of injuries were recorded. The injuries were further graded according to four different scales. It was found that 65% of the injuries were sustained at work, 15% in domestic environments, 7.6% during sports or recreational activities, and 6.5% in traffic accidents. Injuries caused by heavy machinery amounted to 26.7% and the electric saw was the second most common cause of injury accounting for 9.4% of injuries. Crush injuries occurred in 37.8%. The incidence of hand injury is estimated to be 600 per 100,000 population annually. The pattern of hand injuries bears some similarities and differences to published series. A comparison with data obtained in Hong Kong in the 1970s shows that major changes have occurred. We need continual surveillance of hand injury patterns.

Journal Article↗

Bridging nerve defects with differently treated muscle grafts: assessment of microsphere technique for measurement of blood flow in rats.

OBJECTIVE: To select advanced points from differently treated muscle grafts and explore a new conduit to bridge nerve defects. METHODS: A total of 70 Sprague-Dawley rats were employed in this experiment. We applied a frozen probe to freeze the muscle in situ to disrupt any cellular elements of the local muscle grafts, but blood vessels to the muscle were carefully preserved. Radioactive microsphere technique was employed to visualize the blood supply to the muscle grafts. Immunohistochemical staining and ultrastructural observation were also carried out to assess the results of nerve regeneration. RESULTS: The in-situ frozen muscle grafts were revascularized within the first 3 days, which led to fast migration of macrophages and Schwann cells. That was really reflected in the final results: the early incursion of regenerating axons, more regenerating axons at the early stage both in the grafts and distal stumps, and thicker myelin sheath of regenerating axons. CONCLUSIONS: The in-situ frozen autogenous muscle graft is useful in the repair of sciatic nerve of rats. In the thicker and longer grafts the benefits will be more remarkable. It will be the most useful technique for nerve repair, especially in the repair of a large nerve gap in a poor recipient bed.

Animals↗

Free posterior tibial perforator flap: anatomy and a report of 6 cases.

Anatomy of cutaneous perforators of the posterior tibial artery were studied in 20 limbs of 10 cadavers. The majority of the perforators (n = 74, 61%) were located in the middle two quarters of the leg, at an average of 18.6 cm (s.d. 4.5 cm; range 10.5-26 cm) from the medial malleolus, or around 54% (s.d 16%) of the length of the leg. There were usually 3 or 4 perforators in this region, with an average caliber of 1.5 mm (s.d. 0.2 mm; range 1-2 m.m.) and an average length from the posterior tibial artery to the skin of 4.0 cm (s.d. 1.3 cm; range 2.5-6 c.m.). A free fasciocutaneous skin flap based on one of these perforators (the posterior tibial perforator flap, PTP flap) was successfully transplanted in 6 cases. This modified technique of the posterior tibial flap enables the surgeon to retain the posterior tibial artery when the skin of the medial aspect of the leg is chosen to be used as skin flap donor.

Adult↗

Brachial plexus injury in association with fracture-dislocation of the shoulder.

Anterior dislocation of the shoulder is generally not associated with neurological compromise. We report three patients in whom a brachial plexus injury was caused by an anterior dislocation of the shoulder. One patient was further complicated by vascular involvement. The forces producing the injury are usually small, and the neurological trauma is likely to be neuropraxia. Conservative management is usually successful, and, in our patients, recovery took place after an average of six months.

Adolescent↗

Sequential flap transplantations for total reconstruction of avulsion amputation of the fingers--a case report.

The degloved and partially amputated ring and middle fingers of the left hand of a 40-year-old male was re-surfaced with two flaps transplanted sequentially: the toe wrap-around flap and the reversed pedicled metacarpal flap. Sensate and non-glabous skin was restored to the tip of the finger stumps as well as a supple full thickness reconstruction of the web space was achieved.

Adult↗