W. Bradford Rockwell

Extensor tendon: anatomy, injury, and reconstruction.

Although seemingly simple in its anatomy and function, the extensor mechanism of the hand is actually a complex set of interlinked muscles, tendons, and ligaments. A thorough understanding of the extensor anatomy is required to understand the consequences of injury at various levels. Reconstructive options must restore normal function. Whereas primary repair of anatomic structures is frequently possible in acute injury, it is rarely possible in chronic situations. Technically exacting procedures may be necessary to restore function.

The subscapular arterial tree as a source of microvascular arterial grafts

The subscapular arterial tree may be used as a source of microvascular grafts to replace damaged or diseased portions of arteries, particularly in the hand and forearm. By studying cadaver dissections, it is possible to estimate the number of branches that may be found at different arterial segment lengths from the origin of the subscapular artery. Fifty-five preserved cadaver subscapular arterial trees were dissected, and the branching patterns were documented. Three major arterial branching patterns of the subscapular artery were observed with one, two, and three major branches to the serratus anterior in 60 percent, 29 percent, and 9 percent of the cases, respectively. The authors determined the number of 1-mm-diameter, 1-cm-long branches arising from each of six 3-cm regions of the arterial tree measured from the origin of the sub-scapular artery to the end of the longest terminal branch. The probability of finding at least one usable terminal branch that is at least 12.0 cm in length was found to be 98 percent. Typically, there are two to five useful branches at this distance. Such information may help surgeons fine tune their process of selecting an appropriate arterial donor site for a particular arterial defect and supports the use of the subscapular arterial tree as a donor site for microvascular arterial grafts.

Advances in extensor tendon diagnosis and therapy.

Learning Objectives: After studying this article, the participant should be able to: 1. Identify clinical situations in which hand sonography can result in the detection of partial extensor tendon tears. 2. Identify the limitations of magnetic resonance imaging in diagnosing extensor tendon tears. 3. Understand the various postoperative therapeutic protocols for extensor tendon repair. 4. Choose the appropriate surgical repair and postoperative therapeutic protocol for a specific extensor tendon injury. 5. Identify the social and economic variables that may influence the availability and efficacy of the various postoperative therapeutic protocols. Background: This article describes how the application of radiographic imaging facilitates the earlier detection and differentiation of extensor tendon injuries. Furthermore, it defines the best surgical procedure and postoperative therapy for a specific injury. Methods: A literature review was performed of extensor tendon injury articles published since 1989. Results: High-resolution sonography was more accurate than physical examination and magnetic resonance imaging in detecting extensor tendon injuries. Traditional postoperative static splinting was equivalent to early motion protocols for all uncomplicated thumb injuries and zone 1 to 3 injuries of the second through fifth digits. The only definable benefit of early motion therapy compared with static splinting was a quicker return to final function for proximal zones of injury in the second through fifth digits. The results of early active and passive motion, measured at 6 months, were comparable to those from static splinting. A higher rupture rate for early active motion and greater cost for early active and passive motion were noted compared with static splinting. Conclusions: High-resolution sonography allows identification of difficult to diagnose partial and complete extensor tendon injuries. Static splinting should remain the postoperative standard of care for extensor tendon injuries to the thumb and distal zones of injury for digits 2 through 5. The best therapy protocol for proximal zones of injury should be individualized based on social and economic variables.

The deep inferior epigastric artery: anatomy and applicability as a source of microvascular arterial grafts.

Background: Arterial grafts are superior to venous grafts when used for microvascular grafting procedures. Advantages of arterial grafts include anatomical taper, improved size match, improved handling characteristics, and superior patency rates. The deep inferior epigastric artery may be used as a source of microvascular graft to replace damaged or diseased arterial segments. By studying cadaver dissections, it is possible to estimate the clinically usable length and caliber of the deep inferior epigastric artery. Methods: Thirty-four preserved cadavers were dissected and 63 deep inferior epigastric arterial systems were removed and measured. The deep inferior epigastric artery was used as an arterial conduit to bypass across nine wrists in eight patients. Results: The mean length from the external iliac artery to the point at which the vessel displayed an external diameter of 1 mm was 14.06 ± 2.54 cm. The deep inferior epigastric artery has been used in nine clinical cases as an arterial conduit to bypass distal to the wrist. All nine bypasses were patent 1 year postoperatively, without donor-site complication. Conclusion: The deep inferior epigastric artery is a morphologically reliable and clinically useful source of arterial grafts.

Inadequate Enoxaparin Dosing Predicts 90-day Venous Thromboembolism Risk among Plastic Surgery Inpatients: An Examination of Enoxaparin Pharmacodynamics

INTRODUCTION Evidence-based plastic surgery guidelines support the effectiveness of once daily enoxaparin prophylaxis. Despite prophylaxis, one in 25 highest risk patients has a VTE event. We examined the pharmacodynamics of standard enoxaparin doses in plastic surgery patients to examine whether patient-level factors predict enoxaparin metabolism, whether inadequate enoxaparin dose predicts downstream VTE events, and whether a pharmacist-driven dose adjustment protocol was effective. METHODS We recruited adult plastic surgery patients who received post-operative enoxaparin at 40mg daily. Steady state peak anti-Factor Xa (aFXa) levels, a marker of enoxaparin effectiveness and safety, were drawn. Patients with out of range aFXa levels had real-time dose adjustment based on a written protocol. Patients were followed for 90-day VTE events. RESULTS 94 patients were recruited, and 44% had in range peak aFXa levels in response to standard enoxaparin dosing. Patient-level factors including extent of surgical injury and gross weight were independent predictors of enoxaparin metabolism. Patients with low aFXa levels were significantly more likely to have 90-day VTE (10.2% vs. 0%, p=0.041). Real time dose adjustment allowed a significantly increased proportion of patients to have in range levels (67.1% vs. 44.3%, p=0.002). CONCLUSION Based on pharmacodynamic data, the majority of plastic surgery patients receive inadequate enoxaparin prophylaxis using fixed dosing. Patient-level factors can predict how patients will metabolize enoxaparin, and patients who receive inadequate enoxaparin prophylaxis are significantly more likely to have downstream VTE events. Individualization of enoxaparin prophylaxis may minimize peri-operative VTE risk and further improve patient safety after plastic and reconstructive surgery procedures.BACKGROUND Evidence-based plastic surgery guidelines support the effectiveness of once-daily enoxaparin prophylaxis. Despite prophylaxis, one in 25 highest risk patients has a venous thromboembolism event. The authors examined the pharmacodynamics of standard enoxaparin doses in plastic surgery patients to examine whether patient-level factors predict enoxaparin metabolism, whether inadequate enoxaparin dose predicts downstream venous thromboembolism events, and whether a pharmacist-driven dose-adjustment protocol was effective. METHODS The authors recruited adult plastic surgery patients who received postoperative enoxaparin at 40 mg/day. Steady-state peak anti-factor Xa levels, a marker of enoxaparin effectiveness and safety, were determined. Patients with out-of-range anti-factor Xa levels had real-time dose adjustment based on a written protocol. Patients were followed for 90-day venous thromboembolism events. RESULTS Ninety-four patients were recruited, and 44 percent had in-range peak anti-factor Xa levels in response to standard enoxaparin dosing. Patient-level factors including extent of surgical injury and gross weight were independent predictors of enoxaparin metabolism. Patients with low anti-factor Xa levels were significantly more likely to have 90-day venous thromboembolism (10.2 percent versus 0 percent; p = 0.041). Real-time dose adjustment allowed a significantly increased proportion of patients to have in-range levels (67.1 percent versus 44.3 percent; p = 0.002). CONCLUSIONS Based on pharmacodynamic data, the majority of plastic surgery patients receive inadequate enoxaparin prophylaxis using fixed dosing. Patient-level factors can predict how patients will metabolize enoxaparin, and patients who receive inadequate enoxaparin prophylaxis are significantly more likely to have downstream venous thromboembolism events. Individualization of enoxaparin prophylaxis may minimize perioperative venous thromboembolism risk and further improve patient safety after plastic and reconstructive surgery procedures. CLINICAL QUESTION/LEVEL OF EVIDENCE Therapeutic, II.

Thumb replantation using arterial conduit graft and dorsal vein transposition.

Thumb amputations are debilitating injuries to the hand. Replantation should be attempted in most clinical situations.1 Sharp injuries may not produce a significant zone of injury, but avulsion and crush injuries will. Avulsion amputations generally have a worse prognosis after replantation.2 In these situations, debridement of arteries and veins in the zone of injury is necessary to minimize thrombosis following revascularization. Intact side branches will usually indicate arterial segments free of intimal injury. Sufficient vessel length may not remain for primary anastomosis. Traditionally, segmental vessel defects have been managed using vein grafts because of their superficial location and abundance.1,3,4 However, vein grafts have several disadvantages compared with arterial grafts. The presence of valves in the venous system requires that the valves be removed or that the graft be reversed to prevent restricted blood flow. Furthermore, the luminal diameters and wall thicknesses of recipient arteries rarely match those of vein grafts. These discrepancies are exacerbated when the large proximal ends of vein grafts must be connected to the smaller distal ends of arterial branches. This size mismatch may cause technical difficulties and lead to turbulence and kinking, which are common causes of thrombosis. In addition, veins have a less developed tunica media, which leads to thinner venous walls, causing veins to be more difficult to handle.3 When compared with vein grafts, arterial grafts are superior in several ways.5 If a segmental arterial defect exists, we preferentially use an arterial conduit to reconstruct the defect. If segmental injury occurs to the dorsal veins, a graft is necessary for venous reconstitution. A vein graft has appropriate anatomical reverse taper with reasonable size match. However, two anastomoses are necessary. The increasing number of anastomoses increases the chance of thrombosis. A constant dorsal vein from the first dorsal web space, and extending to the dorsal radial aspect of the index finger, can be transposed to the dorsum of the thumb.4,6 The length is sufficient to reach the interphalangeal joint. Only one distal anastomosis is required to reestablish venous outflow of the thumb. We present an innovative technique and our experience with arterial conduit graft and dorsal vein transposition for thumb replantation.