Continuous versus intraoperative expansion in the pig model.

Continuous tissue expansion utilizing a continuous infusion device that maintains a constant expander pressure was previously demonstrated to be feasible and successful in obtaining rapid tissue expansion in a canine model. Intraoperative tissue expansion has been described and has gained some clinical acceptance as a method to gain rapid expansion. We compared the efficacy of continuous tissue expansion versus intraoperative tissue expansion in a piglet model. After completing a pilot study, continuous tissue expansion was performed in six pigs (14.5 to 20 kg) on one flank over a 3-day period utilizing an improved prototype device; at the termination of continuous tissue expansion, intraoperative tissue expansion was performed on the opposite flank. There were no complications or continuous tissue expansion device malfunctions. Intraoperative tissue expansion gave a true gain in area of 7.4 percent, while continuous tissue expansion produced a 22 percent gain (p < 0.02). When the effects of both recruitment and expansion were added, continuous tissue expansion gave a dividend of 286 percent versus 192 percent for intraoperative tissue expansion (p < 0.01). Biomechanically, intraoperative tissue expansion skin showed few differences from unexpanded skin, while continuous tissue expansion skin showed a significant increase in stress relaxation (47.78 versus 38.74) and decrease in breaking strength. Histologic analysis revealed some epidermal hyperplasia and inflammation surrounding the continuous tissue expansion expander and some vascular congestion over the intraoperative tissue expansion expander. We conclude that continuous tissue expansion is superior to intraoperative tissue expansion and that the prototype device may be useful clinically.

Grip strength before and after carpal tunnel decompression.

We prospectively studied preoperative and postoperative grip and pinch strength in 21 patients having 30 consecutive median nerve decompressions for carpal tunnel syndrome. All procedures were done by one surgeon. Each hand operated on served as its own control and was studied by the same therapist preoperatively and at monthly intervals for 6 months after the procedure. An initial decline in both grip and pinch strength was noted in most hands during the first postoperative month. Eighty percent or more grip strength was regained in 65% of the hands at 2 months and in 81% at 3 or more months. In those hands (65%) that regained at least 100% of their preoperative grip strength at 3 or more months, there was an average increase in maximal grip of 56%, as compared with an average decrease of 20% in the remaining hands (35%).

Bilateral scaphoid ganglion cysts in an adolescent.

We describe an adolescent girl with symptoms secondary to bilateral, symmetrical ganglion cysts of the scaphoid bones. From the roentgenographic and operative findings, it was believed that the cysts were the penetrating type. The patient is among the youngest reported with carpal bone ganglion cysts and the first with bilateral scaphoid cysts completely described in the English-language medical literature.

Distinguishing biomechanical properties of intrinsic and extrinsic human wrist ligaments.

Two intrinsic (scapholunate and lunotriquetral) and two extrinsic (radiolunate and radiocapitate) wrist ligaments were studied at high and low elongation rates (1 and 100 mm/min). Statistically significant differences among all four ligaments were noted for the viscoelastic and elastic components of stress versus strain for the fully recoverable strain and early permanent deformation stress for all ligaments. Intrinsic ligaments became permanently deformed at statistically significantly higher strain levels than the extrinsic ligaments and accept larger permanent deformation at strain levels below evident fiber failure. Ultimate strength data demonstrated significant rate dependency for stress and strain for all ligaments. Intrinsic ligaments failed statistically greater stress and strain levels than the extrinsic group. Some clinical implications of these findings are discussed.

Continuous versus conventional tissue expansion: experimental verification of a new technique.

Historically, tissue expansion is a prolonged process, typically requiring at least 6 weeks to complete. Recently, interest has increased in shortening this time period. In the current study, a continuous infusion device maintaining constant expander pressure less than capillary filling pressure was used in a canine model in seven dogs to minimize the time period needed to achieve significant expansion. There were no complications, except one device malfunction, corrected by changes in design. The process was shown to be a safe and effective means of producing amounts of expansion similar to traditional methods in approximately 72 hours, with expansion of 28 percent (n = 6) for continuous tissue expansion (CTE) versus 34 percent (n = 6) for a 2-week rapid expansion protocol. This expansion was derived from either stretch of preexisting tissue (46 percent for CTE, 35 percent for 2-week expansion) or recruitment of adjacent tissue. The clinical application of continuous tissue expansion could permit the advantages of tissue expansion to be obtained in many more situations than are currently available to traditional tissue expansion techniques.

The relationship of retrobulbar hematomas to vision in cynomolgus monkeys.

An experimental model has been developed to measure the effect of retrobulbar hematomas on functional vision in cynomolgus monkeys. In this model, functional vision was quantitated using flashed evoked visual potentials in five monkeys following creation of retrobulbar hematomas. In one monkey used as a control, functional vision remained impaired for 180 minutes following induction of retinal ischemia by increased intraorbital pressure. In two monkeys in which increased intraorbital pressure was relieved by anterior chamber paracentesis following 15 minutes of retinal ischemia, flashed evoked visual potential promptly returned to baseline level. In two additional monkeys in which increased intraorbital pressure was relieved following 30 minutes of retinal ischemia, flashed evoked visual potentials improved but never returned to baseline levels. This study demonstrates the usefulness of flashed evoked visual potentials in measuring functional vision in cynomolgus monkeys. This experimental model should prove useful in evaluating the effects of increased intraorbital pressure on functional vision and the effect of intervention on impaired vision due to retrobulbar hematomas. Further studies with larger numbers of animals are needed to clarify these preliminary studies and document longer-term effects of retinal ischemia secondary to retrobulbar hematomas.

Optimum management of hand blast injuries.

A series of 27 blast and gunshot injuries of the hand is presented. These wounds exhibit a spectrum of complexity and may include extensive soft tissue trauma complicated by burns, foreign bodies, fractures and amputations. A systematic management sequence is outlined to evaluate, treat, reconstruct and rehabilitate these hands, with the primary goal of obtaining early maximal function. Since these injuries vary in nature and complexity, this management sequence is specifically adapted to deal with the individual injury. A "reconstructive ladder" of techniques is utilized, ranging from "simple" (e.g., direct closure, skin grafts, local flaps) to "complex" (free flaps, toe-to-thumb transfer). The individual procedure selected is the most straightforward, consistent with expediency and early return of a functional hand. The return of these hands to function has been facilitated by recent advances in tissue assessment, free tissue transfer, and skilled hand therapy.

Coincident rupture of the scapholunate and lunotriquetral ligaments without perilunate dislocation: pathomechanics and management.

Wrist injuries causing coincident disruptions of the scapholunate and lunotriquetral ligaments commonly result in perilunate dislocations. This article (1) describes our management of eight patients with wrist pain after coincident scapholunate and lunotriquetral ligament disruptions in the absence of perilunate dislocation; and (2) reports the results of biomechanical testing of some of the extrinsic and intrinsic wrist ligament and interprets these data to explain the injury seen clinically. The diagnosis of ligament failure was made on the basis of history, physical examination, arthrography and surgical exploration. Surgical treatment of seven patients consisted of concomitant scapho-trapezio-trapezoid fusion and lunotriquetral fusion. Three of seven patients were free of pain, two had pain only at the extremes of motion, and two required additional surgery. Biomechanical analysis of the scapholunate and lunotriquetral ligaments and two extrinsic wrist ligaments, the radiolunotriquetral and the radioscaphocapitate, confirmed the clinical suspicion that the intrinsic ligaments could be completely disrupted while the extrinsics are only partially injured. Such a scenario could account for the residual stability that prevents the development of perilunate dislocations. Coincident disruption of the scapholunate and lunotriquetral ligaments in the absence of perilunate dislocation is an unusual injury. Treatment with lunotriquetral fusion and scapho-trapezio-trapezoid fusion restored functional use in five of seven wrists while maintaining wrist motion.

Calcification of breast implant capsule.

We have presented a case of bilateral capsular calcification, an extremely rare but clinically important complication of augmentation mammoplasty. Little is known about its pathogenesis, but it is believed to be related to the presence of molecular silicone and/or Dacron patches in the pericapsular environment. This condition may mask calcifications of the breast due to carcinoma, and it often exacerbates the symptoms of capsular contracture. We recommend removal of the calcified capsules and replacement of the implants in the submuscular position.

Effect of anterior chamber paracentesis on decreased retinal circulation due to retrobulbar hematoma in dogs.

An experimental canine model for blindness following blepharoplasty was developed to demonstrate occlusion of retinal circulation resulting from simulated retrobulbar hematoma. Seven mongrel dogs were studied, monitoring retinal vascular patterns by funduscopic examination and intraocular pressure by pneumotonometry. Anterior chamber paracentesis was performed in five dogs 10 minutes after injecting blood retrobulbarly, with an immediate decrease in pressure and return of retinal blood flow. In two dogs without paracentesis, increased pressure and blindness persisted. Anterior chamber paracentesis has been shown to reduce intraocular pressure from hematoma of the retro-orbital area in dogs. Although controversial, anterior chamber paracentesis may represent a useful temporizing adjunct in the treatment of increased intraocular pressure and impaired vision from hematoma following blepharoplasty.

Dynamic wrist motion analysis using six degree of freedom sensors.

Dynamic motion analysis of the wrist in the past has been a tedious and often impossible task to undertake. However, such motion analysis is now practical with the use of the McDonnell Douglas 3Space Digitizer and Macintosh microcomputer. The feasibility of using this system with multiple electromagnetic sensors for upper extremity kinematics analysis has been previously described by our laboratory. This work has now been extended to the dynamic analysis of wrist motion during performance of a work task by placing one sensor on the hand and the other on the distal forearm. The 3Space Digitizer source creates a low-frequency magnetic field. Sensors placed within the field have a specific position and orientation with respect to a coordinate system defined by the source. The x, y, z coordinates and theta, phi, psi orientation angles of the sensors on the subject's extremity are measured during task performance at a rate of approximately 19 readings per second. Analysis of this data provides a "motion signature" of the task under study. After the task completion the data obtained from the digitizer (orientation of the hand and forearm with respect to the digitizer's source) is stored on a computer disk and then reduced using mathematical transformations to obtain instantaneous radial/ulnar deviation (RUD), flexion/extension (FE), and supination/pronation (SP). The transformed data is displayed graphically as RUD vs. time, or FE vs. time and SP vs. time for each given task. A frequency analysis for each task performed is obtained with the use of the Macintosh microcomputer and a Fast Fourier Transform.(ABSTRACT TRUNCATED AT 250 WORDS)

An analytical model for intra-arterial versus intravenous infusion of Adriamycin.

Intra-arterial infusion of Adriamycin (doxorubicin) has increasing clinical usage in various chemotherapeutic protocols for treatment of sarcomas and other tumors. This route of drug delivery is generally believed to provide better delivery of drug to the tumor than intravenous infusion. However, the differential delivery of drug to the tumor for the two methods has not been adequately described. An analytical model has been developed to investigate the hemodynamics of intra-arterial Adriamycin in terms of various parameters including location of injection; tumor site, resistance, and blood flow; relative resistances and blood flows in adjacent structures; and the pharmacokinetics of Adriamycin plasma concentration. A three-phase exponential model is fitted to experimental plasma concentration measurements and used in the formulation of equations describing tumor Adriamycin exposure. For typical values of tumor blood flow (4-20 ml/min/100 gr) and size (1,000 gm), it is estimated that with intravenous injection of Adriamycin the tumor is exposed to only 4-19% of the injected drug. Substantially higher doses of Adriamycin are delivered to the tumor by intra-arterial injection. Typically 3-4 times more drug flows through the tumor when injected into a major artery proximal to the tumor-feeding vessel, as into the common femoral artery for a sarcoma of the leg. With injection directly into a major tumor arterial feeding vessel, as much as 6 to 26 times the mass of drug is delivered to the tumor compared to a comparable intravenous injection.hus, smaller doses of drug should be required for tumorcidal activity and systemic toxicity of the drug may be reduced.(ABSTRACT TRUNCATED AT 250 WORDS)

A control unit for maximal-rate continuous tissue expansion (CTE).

Subcutaneous or submuscular tissue expansion has become a major tool for the reconstructive plastic surgeon in the repair of difficult wounds and in breast reconstruction. This technique can provide additional or replacement tissue with good match in color, sensation, texture and adnexal characteristics. A major limitation of the technique is the time required for periodic tissue expansion to the required volume in the clinical setting, typically taking from a few weeks to several months. Conceptually, the maximum rate possible for safe clinical tissue expansion would result from continuous maintenance of tissue expander pressure just below capillary filling pressure (continuous tissue expansion, CTE). A control device with this capability would have important clinical and research applications. A self-contained portable control unit (patent pending) for CTE has been designed, fabricated, and testing initiated in a dog model. The 4-lb unit includes a 250-cc fluid reservoir, power pack, pressure transducer (Microswitch 160 PC), pump (Spalding 701A), feedback circuits and memory (2-lb power pack, 2-lb controller and reservoir). Preselected constant pressure (15-50 mmHg +/- 0.1 mmHg) can be maintained in a tissue expander with a maximal flow rate of 16 cc/hr for approximately 18 hours before change of the NiCad battery pack. A digital memory records pressure and volume infused and transfers this data to a Macintosh computer after completion of expansion. Verification of this prototype control unit is presently underway. Initial data suggests that the time required for complete filling of a subcutaneous tissue expander in a dog model can be reduced to approximately 72 hours. Several potential clinical applications and variations of this device are discussed.

Free serratus anterior muscle transplantation for hand reconstruction.

Free transplantation of the serratus anterior muscle has allowed salvage or reconstruction of difficult hand injuries with advantages compared to traditional methods. Free muscle tissue adds vascularity to poorly vascularised and potentially infected wounds and allows hand elevation and early mobilisation. Dynamic reinnervation is possible with segmental preservation of the long thoracic nerve. The serratus anterior muscle is easily harvested and has a long, reliable vascular pedicle. It is thin, easily contoured to the defect and can be separated into its component slips. The muscle provides stable coverage when covered with a meshed split thickness skin graft. Scapular winging does not occur since only the lower two or three slips of muscle are used. The muscle has been used in 15 complex hand wounds, three within a week of revascularisation or digital replantation for hand salvage. Three dynamic muscle transfers were performed to restore thumb opposition with one simultaneous toe-to-thumb transplantation.

Ganglions of the hand and wrist.

The ganglion is the most common soft tissue tumor of the hand and wrist, originating from the joint capsule or tendon sheath. Accurate diagnosis and proper treatment of these entities require a thorough knowledge of the anatomy of the wrist and hand as well as of the ganglion itself. Definitive therapy is based on total surgical removal of the cyst and its connections to the joint or tendon sheath.

Miniature implantable laser Doppler probe monitoring of free tissue transfer.

A 2.5-mm fiber-optic laser Doppler flowmetry probe has been applied in an experimental dog model as well as in 5 clinical cases to provide continuous readout of deep tissue perfusion. The rectus abdominis muscle in the dog was used for the experimental verification of the probe, which has a linear correlation with flow rate and a rapid response (6 seconds) to arterial occlusion and venous occlusion (20 seconds). Four of the 5 free tissue transfers survived with the laser Doppler instrument correctly identifying the lack of flow, both intraoperatively and postoperatively, in the failed flap. This probe greatly extends the versatility of laser Doppler flow measurement in the clinical setting and may be nearly an ideal probe for monitoring free tissue transfer, particularly muscle.

Intrinsic and extrinsic wrist ligaments: biomechanical and functional differences.

The human wrist is a complex arrangement of bones and ligaments and functions to position the hand and transfer forces between the hand and forearm. The carpal ligaments (extrinsic - connect carpal bones and forearm; and intrinsic - interconnect carpals) are vitally important for wrist function and still incompletely understood biomechanically. Our previous investigations have described the rate-dependent viscoelastic behavior of the scapholunate (intrinsic) ligament. This study demonstrates significant differences in the biomechanical behavior between the intrinsic and extrinsic classes of ligaments. Bone-ligament-bone preparations were obtained by dissecting fresh and fresh-frozen cadaveric specimens. Two intrinsic (IL) [scapholunate (SL, 7) and lunotriquetral (LT, 9)] and two extrinsic (EL) [radiolunate (RL, 2) and radioscaphocapitate (RC, 3)] ligaments were extensively tested on a Monsanto Tensometer testing apparatus in axial loading at 0.5, 1, 5, 10, 50, and 100 mm/min. Significant differences in behavior were noted between the intrinsic and extrinsic ligaments in (1) maximum stress at ultimate yield (IL greater than EL), (2) maximum strain at ultimate yield (IL greater than EL), (3) strain level for onset of plasticity (IL greater than EL), and (4) rate and amount of stress relaxation (IL greater than EL). These results indicate that the intrinsic ligaments are biomechanically quite different than the extrinsic ligaments. These distinctions have important implications for wrist function and pathomechanics.