An analysis of the pull-out strength of 6 suture loop configurations in flexor tendons.

PURPOSE: New, stronger suture materials have been introduced for flexor tendon surgery. The advantage of these materials can be lost if the suture loop pulls out from the tendon. The aim of this study was to compare the ability of various locking loops to grip the tendon. METHODS: We inserted 4 different standard and 2 experimental locking loops with 200-µm nitinol wire into human cadaveric flexor digitorum profundus tendons. The standard loops were: group 1, cruciate; group 2, Pennington modified Kessler; group 3, cross-stitch; and group 4, Lim-Tsai. The experimental loops were: group 5, a composition of Pennington modified Kessler with a cross-stitch loop; and group 6, a locking Kessler type of loop with a superficial transverse component. We loaded the loops until failure. We recorded the pull-out strength and stiffness and documented failure mechanisms during the pull-out test. RESULTS: The cruciate loop had the weakest holding capacity, 20 N, which was significantly less than in groups 2 to 6. The cross-stitch loop, Lim-Tsai loop, and modified Kessler loop performed similarly (36 N, 37 N, and 39 N, respectively). The experimental loops had the highest pull-out strength (group 5, 59 N; and group 6, 60 N, both significantly greater than groups 1 to 4). The mode of failure was pull-out for all of the standard loops and 7 of the experimental loops. Of 20 experimental loops, 13 failed by suture rupture. CONCLUSIONS: The 2 experimental loop configurations demonstrated higher pull-out strength and may have advantages when used with newer and stronger suture materials. The number of the locking components in the loops and the way the tension is transmitted to the tendon fibrils explain the results. CLINICAL RELEVANCE: The loops presented in this study and that grip the tendon better may be useful with new materials that have high tensile strength.

Nickel-titanium wire in circumferential suture of a flexor tendon repair: a comparison to polypropylene.

PURPOSE: Nickel-titanium (NiTi) has been proposed as an alternative material for flexor tendon core suture. To our knowledge, its suitability as a circumferential suture of flexor tendon repair has not been investigated before. The purpose of this ex vivo study was to investigate the biomechanical properties of NiTi circumferential repairs and to compare them with commonly used polypropylene. METHODS: Forty porcine flexor tendons were cut and repaired by simple running or interlocking mattress technique using 100 microm NiTi wire or 6-0 polypropylene. RESULTS: The NiTi circumferential repairs showed superior stiffness, gap resistance, and load to failure when compared to polypropylene repairs with both techniques. CONCLUSIONS: Nickel-titanium wire seems to be a potential material for circumferential repair of flexor tendons.

Bypass surgery or percutaneous transluminal angioplasty to treat critical lower limb ischaemia due to infrainguinal arterial occlusive disease?

OBJECTIVES: To define the role of bypass surgery and percutaneous transluminal angioplasty to manage critical limb ischaemia due to infrainguinal arterial occlusive disease. DESIGN: Retrospective review. SETTING: Regional hospital, Hong Kong. PATIENTS: Consecutive patients treated for critical limb ischaemia, for whom data were prospectively collected in those who underwent: (i) infrainguinal percutaneous transluminal angioplasty first, or (ii) infrainguinal bypass surgery. RESULTS: Among patients with critical lower limb ischaemia, 364 consecutive individuals having infrainguinal bypass operations and 100 having percutaneous transluminal angioplasty first were compared. The latter patients were older (77 vs 74 years, P=0.014) and had more co-morbidities but higher ankle pressure than those having bypass surgery. In the angioplasty-first group, 74% had favourable lesions (classified as TransAtlantic Inter-Society Consensus A/B). In the bypass group, operative mortality was higher (4% vs 1%, P=0.03) than that in the angioplasty-first group. Hospital mortality was comparable (8% vs 3%, P=0.15). In the bypass group, median hospital stay was longer than that in the angioplasty-first group (24 vs 4 days, P<0.001), and postoperatively they also had a higher median ankle-brachial index (0.92 vs 0.70, P<0.001) and superior long-term patency. In the bypass group, American Society of Anesthesiologists class 4 patients suffered very high operative and hospital mortality (15% and 31%, respectively). Long-term patency of percutaneous transluminal angioplasty depended on the TransAtlantic Inter-Society Consensus class of the treated lesion. Limb salvage rates at 3 years were 89% and 78% for percutaneous transluminal angioplasty first and surgical bypass, respectively (P=0.046). Long-term survival was poorer in the percutaneous transluminal angioplasty-first group (21% vs 51% at 5 years, P=0.04). CONCLUSION: Infrainguinal bypass and percutaneous transluminal angioplasty are complementary. For TransAtlantic Inter-Society Consensus A and B lesions, percutaneous transluminal angioplasty should be offered first. For American Society of Anesthesiologists class 4 patients, percutaneous transluminal angioplasty should be considered first, regardless of the TransAtlantic Inter-Society Consensus class.

Flap Related Complications Requiring Secondary Surgery in a Series of 851 Local Flaps Used for Fingertip Reconstruction.

BACKGROUND: Local flaps are widely used to cover fingertip defects. Errors in design or technical execution of the flap may lead to morbidity and additional surgical procedure. The purpose of this study was to review flap related complications requiring unplanned secondary surgery to characterize preventable issues. METHODS: 851 local flaps were used to reconstruct fingertip defects during a 9-year period. Patients requiring unplanned secondary surgery to address flap related complications were subjected to analysis. RESULTS: 31 of 851 flaps (3.6%) required unplanned secondary surgery because of flap related complications. The most reliable flap was VY advancement flap with only one (0.3%) re-operation. The reverse vascular island flap, cross finger flap, and neurovascular island flap were associated with the comparable number of complications (8.0%; 6.3%; and 3.8% respectively). Total or partial necrosis was the cause for re-operation in 6 patients (0.7%). The typical reason for secondary surgery was inadequate soft tissue cover of the tip with homodigital neurovascular island flap and flexion contracture with reverse vascular island flap. Cross finger flaps were revised because of poor graft take at the donor site, bulky flap or flap necrosis. CONCLUSIONS: Local flaps are reliable operations to cover fingertip defects. Each flap has potential pitfalls, which may be avoided if the surgeon is aware of them.

Common bacterial infections of the hand.

Infections of the hand are commonly encountered in general practice. Delay in diagnosis increases the risk of tissue loss and functional impairment. Staphyloccocal infections are most common, but polymicrobial infections are often seen in immunocompromised patients. In this pictorial essay, important and common conditions are illustrated to demonstrate key points and pitfalls in diagnosis and management.

Influenza virus sialidase: effect of calcium on steady-state kinetic parameters.

Ca2+ increases the initial rate of activity of sialidase from influenza virus (A/Tokyo/3/67). Increasing ionic strength also activates influenza virus sialidase. When ionic strength is controlled, smaller but still significant Ca2+ effects are observed, with Vmax/Km increased from 0.8.10(5) to 1.4.10(5) M-1 s-1 and Vmax increased from 6.3 to 9.5 s-1 by saturating Ca2+. The Ki of the competitive inhibitor 2,3-dehydro-2-deoxy-N-acetylneuraminic acid was decreased from 2.7.10(-6) to 1.15.10(-6) M after the addition of saturating Ca2+. The data show that Ca2+ exerts a specific effect on Vmax/Km, leading to an increased rate of interaction of substrate with the enzyme. The Kd-app for the Ca2(+)-sialidase complex is 2 mM. Except for Mg2+ which behaves similarly to Ca2+, other mono- and divalent cations have little specific effect on sialidase kinetics. Sequence analysis of a range of subtypes of sialidases from influenza virus supports the proposal that Ca2+ binds at the subunit interface transmitting a conformational change to the enzyme active site. Ca2+ activation may have a physiological role in switching on sialidase activity during the release of newly synthesised virions from the host cell surface.

Use of laparoscopy in the management of mesenteric venous thrombosis.

Mesenteric vein thrombosis is a relatively rare cause of intestinal ischemia. We present a case of idiopathic superior mesenteric and portal vein thrombosis, which was not associated with any infarcted bowel. The patient was treated successfully with anticoagulation using low-molecular weight heparin and warfarin, and did not require bowel resection. This case highlights the value of diagnostic laparoscopy for assessing intestinal viability in this situation, showing how it avoids the morbidity and complications associated with a formal laparotomy.

Flap reconstruction following high pressure injection injuries of the hand: a report of three cases.

High pressure injection injuries are well known to cause significant injury to the hand, with high amputation rates and poor functional outcome. Surgical treatment consists of early aggressive debridement followed by secondary closure. Flap reconstruction is a reconstruction option which can increase the chance of digit salvage, as well as give an acceptable functional and cosmetic result. We review three cases of flap reconstruction following high pressure injection injuries, and discuss their role in the treatment of these injuries.

Breast cancer detection from MR images through an auto-probing discrete Fourier transform system.

A computer-aided detection auto-probing (CADAP) system is presented for detecting breast lesions using dynamic contrast enhanced magnetic resonance imaging, through a spatial-based discrete Fourier transform. The stand-alone CADAP system reduces noise, refines region of interest (ROI) automatically, and detects the breast lesion with minimal false positive detection. The lesions are then classified and colourised according to their characteristics, whether benign, suspicious or malignant. To enhance the visualisation, the entire analysed ROI is constructed into a 3-D image, so that the user can diagnose based on multiple views on the ROI. The proposed method has been applied to 101 sets of digital images, and the results compared with the biopsy results done by radiologists. The proposed scheme is able to identify breast cancer regions accurately and efficiently.

Comparison of the holding capacity of round monofilament, round multifilament, and flat multifilament nitinol suture loops in human cadaveric flexor tendon.

Tendon repairs done with strong suture materials fail by suture pull out. To avoid pull out, suture loop needs to have a strong grip on the tendon. The aim of this study was to determine whether a single suture loop has a better grip of the tendon when multifilament or flat sutures are used compared with a conventional monofilament round suture. A cross-locking or simple grasping suture loop was placed into the distal end of a human cadaveric tendon using nitinol wire sutures in the following configurations: round monofilament (200 µm), round multifilament (4 × 100 µm), and flat multifilament (4 × 30 µm × 445 µm). The mean pull-out strength of the round multifilament (49.4 N) and flat multifilament sutures (50.7 N) were significantly higher than that of the round monofilament nitinol suture (36.5 N) when a locking loop was used. Suture grip can be improved by using a multifilament suture and a locking type of suture configuration.

Bites to the hand: are they more than we can chew?

Animal bites to the hand caused by dogs, cats and humans are common conditions that general practitioners, emergency physicians and hand surgeons encounter in their practice. These bites are prone to infection and represent great cost to the patient in terms of time, money and disability, if not treated optimally from the outset. Other than lacerations to the skin, injuries to the tendons, nerves, bone and joints are commonplace given their proximity to the skin surface in the hand. Optimal treatment of acute animal bites to the hand should include clearance of contamination by surgical debridement, prophylactic antibiotics and tetanus toxoid, as well as staged reconstruction of all damaged tissue, including the skin, once the wound is deemed clean.

Common congenital hand conditions.

Congenital hand deformities are common but most of these conditions are minor. Polydactyly and syndactyly are the commonest congenital hand conditions for which treatment is sought. The presence of congenital hand deformities has a significant psychological impact on both the parents and child, and in severe cases, can significantly affect limb function. This article reviews the more common hand conditions so that non-specialist physicians can diagnose them and understand their management principles.

Fingertip injuries.

Fingertip injuries are commonly seen by family and emergency physicians. Many of the cases are simple to treat and do not need specialised treatment by a hand surgeon. However, there are certain conditions where early intervention by a hand surgeon is warranted for better functional and aesthetic outcomes. Common injuries include mallet finger injury, crush injuries to the fingertip with resultant subungual haematoma, nail bed laceration, partial or complete amputation of the fingertips, pulp amputations and fractures of the distal phalanges.

Comparison of forearm and conventional Bier's blocks for manipulation and reduction of distal radius fractures.

Forearm-based Bier's block has been advocated as a useful anaesthesic technique in hand surgery. However, there is limited data comparing forearm blocks with the conventional Bier's block. We conducted a randomised controlled trial (n=30) comparing the two techniques of anaesthesia for manipulation and reduction of closed distal radius fractures in an emergency room setting. Pain scores measured using the Visual Analogue Scale during the procedure were used as the primary outcome assessment. There was no significant difference in pain scores between the forearm and conventional Bier's block (mean VAS 18.4 SD 22.10 versus 33.7 SD 29.6). No major complications were observed in either group. The forearm-based Bier block is an effective alternative to the conventional block.

Characterisation of an ionisable group involved in binding and catalysis by sialidase from influenza virus.

The effect of pH on the kinetics of sialidase purified from influenza virus (A/Tokyo/3/67, H2N2) was investigated. A pK of 9.0 for inhibition of the enzyme by three competitive inhibitors, due to an ionisable group in the active site, was observed. A similar pK was observed for V/Km for the fluorogenic substrate 2-(4-methylumbelliferyl)-N-acetyl-alpha-D-neuraminic acid. However, the shape of the V/Km profile indicates that this substrate is sticky. Solvent perturbation experiments indicated that the observed ionisable active site group is likely to be a cationic amino acid. The results provide evidence against the hypothesis that Glu 276 acts as a proton donor in the enzyme reaction and supports the proposal of a role for one of the active site cationic amino acids in binding and catalysis.

Arterial reconstruction for lower limb ischaemia in Hong Kong Chinese.

BACKGROUND: Lower limb ischaemia due to peripheral arterial disease is uncommon in Chinese people, and few arterial bypass operations have been performed. The management of a consecutive series of patients who were admitted to our department with severe lower limb ischaemis between March 1990 and October 1996 is reported here. METHODS: A total of 91 primary arterial bypass operations were performed for 83 patients (eight patients had bilateral, or two procedures). Of these, 84 operations were for foot salvage and seven operations were for debilitating claudication. There were 80 infra-inguinal bypasses, 10 of which required additional femoro-femoral crossover grafts to improve in-flow. The remaining 11 bypass procedures were performed for aorto-iliac occlusion, which included aortobifemoral bypass (5), axillobifemoral bypass (3) and cross-femoral bypass (3) grafts. There were 46 male and 37 female patients, with a median age of 70 years (36-94). RESULTS: Six patients died (6.6%) postoperatively, all of whom were in the foot salvage group. The overall cumulative foot salvage rate and graft patency was 84 and 56%, respectively, at 5 years. CONCLUSIONS: These results justified the use of the same aggressive approach that was adopted in Western countries for the treatment of peripheral arterial disease, which seemed to be an emerging problem in Hong Kong.

Evidence for a sialosyl cation transition-state complex in the reaction of sialidase from influenza virus.

The enzyme mechanism of sialidase from influenza virus has been investigated by kinetic isotope methods, NMR, and a molecular dynamics simulation of the enzyme-substrate complex. Comparison of the reaction rates obtained with the synthetic substrate 4-methylumbelliferyl-N-acetyl-alpha-D-neuraminic acid and the [3,3-2H]-substituted substrate revealed beta-deuterium isotope effects for V/Km ranging over 1.09-1.15 in the pH range 6.0-9.5, whereas the effects observed for V in this pH range increased from 0.979 to 1.07. In D2O, beta DV/Km was slightly increased by 2% and 5% at pD 6.0 and 9.5 respectively, while beta DV was unchanged. Solvent isotope effects of 1.74 were obtained for both beta DV/Km and beta DV at pD 9.5, with beta DV/Km decreasing and beta DV remaining constant at acidic pD. 1H-NMR experiments confirmed that the initial product of the reaction is the alpha-anomer of N-acetyl-D-neuraminic acid. Molecular dynamics studies identified a water molecule in the crystal structure of the sialidase-N-acetyl-D-neuraminic acid complex which is hydrogen-bonded to Asp151 and is available to act as a proton donor source in the enzyme reaction. The results of this study lead us to propose a mechanism for the solvent-mediated hydrolysis of substrate by sialidase that requires the formation of an endocyclic sialosyl cation transition-state intermediate.

Clinical and radiological features of biliary papillomatosis.

Biliary papillomatosis is a rare disease with strong potential for malignant degeneration. Diagnosis is often not easy and most are made intraoperatively. In the present study, five patients with biliary papillomatosis admitted between 1990 and 1997 were reviewed. Their clinical presentation, radiological and biochemical findings were analysed. The aim of the study was to discern a set of characteristic features that would enable an early diagnosis. All of the five patients presented with recurrent episodes of acute cholangitis and epigastric pain with raised serum alkaline phosphatase. Imaging modalities including ultrasound, CT, endoscopic retrograde cholangio-pancreatogram, MRI and magnetic resonance cholangio-pancreatogram were reviewed. Salient imaging features included a dilated biliary tree with multiple ill-defined and fuzzy filling defects or endoluminal frond-like mass lesions. In conclusion, biliary papillomatosis is a rare but important cause of biliary obstruction with relapsing cholangitis and obstructive jaundice. With a healthy index of suspicion, the diagnosis can be reached when the above features are available.

Intestinal intussusception and occlusion caused by small bowel polyps in the Peutz-Jeghers syndrome. Management by combined intraoperative enteroscopy and resection through minimal enterostomy: case report.

UNLABELLED: The Peutz-Jeghers syndrome is a hereditary disease that requires frequent endoscopic and surgical intervention, leading to secondary complications such as short bowel syndrome. CASE REPORT: This paper reports on a 15-year-old male patient with a family history of the disease, who underwent surgery for treatment of an intestinal occlusion due to a small intestine intussusception. DISCUSSION: An intra-operative fiberscopic procedure was included for the detection and treatment of numerous polyps distributed along the small intestine. Enterotomy was performed to treat only the larger polyps, therefore limiting the intestinal resection to smaller segments. The postoperative follow-up was uneventful. CONCLUSION: We point out the importance of conservative treatment for patients with this syndrome, especially those who will undergo repeated surgical interventions because of clinical manifestation while they are still young.

Comparison of a single layer continuous hand-sewn method and circular stapling in 580 oesophageal anastomoses.

A total of 611 patients with carcinoma of the oesophagus or gastric cardia were operated on between July 1982 and December 1989. Resection was performed in 491 patients (one-stage, 483; two-stage, eight), bypass operation in 97, and 23 had exploration alone. The anastomoses of 580 patients with one-stage resection and bypass operations were evaluated. Hand-sewn anastomosis using a single layer of continuous absorbable monofilament suture was performed in 304 patients (221 resections and 83 bypasses). A stapled anastomosis was performed on 276 patients (262 resections and 14 bypasses). Following resection, there were 11 (5 per cent) anastomotic leaks in the hand-sewn group and ten (3.8 per cent) in the stapled anastomosis group (P = 0.69). Excluding anastomotic leaks, hospital mortality and anastomotic recurrence, stricture occurred in 18 of 172 hand-sewn anastomoses (10.5 per cent) and in 57 of 195 stapled anastomoses (29.2 per cent) (P less than 0.001). In patients who had bypass operations there were 12 anastomotic leaks, ten in the hand-sewn group (12.0 per cent) and two in the stapled anastomosis group (14.3 per cent). Only two of the discharged patients with bypass developed anastomotic strictures, a low incidence probably because of short survival. In addition, there were 245 subsidiary anastomoses made in the abdomen by the hand-sewn method as part of the reconstructive procedure, and there was one leak. The results of this non-randomized study suggest that hand-sewn anastomosis using a single layer continuous technique for the oesophagus is as safe as the use of circular staplers; hand-sewn anastomosis is less likely to become stenotic.