[Flap coverage of soft tissue defects after total knee arthroplasty]. / Lappenplastiken bei Weichteildefekten nach endoprothetischem Kniegelenkersatz.

Due to the marginal periarticular soft tissue envelope and the high risk of concomitant soft tissue or periprosthetic infection with the presence of exposed metal or bone, soft tissue defects after total knee arthroplasty are always a relevant surgical problem. Specific patient-related, intra- and postoperative risk factors have been identified and need to be considered during the course of treatment. Often a profound management of underlying infection must accompany the staged defect treatment which could require a prosthesis explantation with secondary revision in the case of a deep infection and involvement of the prosthesis. Four stages of soft tissue defects have been introduced (types A-D) and criteria for differentiation are the overall soft tissue coverage, the exposure, respectively, necrosis of the extensor mechanism, preservation or involvement of the joint capsule and/or an accompanying septic loosening of the prosthesis. The concept of plastic coverage follows a stage-adapted algorithm and includes secondary wound healing and mesh coverage for superficial defects, fasciocutaneous flaps for moderate defects and pedicled or free muscle flaps for deep defect situations with extension into the joint capsule. Crucial factors for a successful therapy include the early identification and precise analysis of defect characteristics, the careful preparation of the wound bed with serial debridements and the diligent flap coverage with early consultation of plastic-surgical expertise.

Is there a difference in outcome (long-term recurrence rate) between emergency and elective pilonidal sinus surgery?

AIM: The influence of surgical craftsmanship and decision making on long-term recurrence rate has not been investigated yet. METHODS: A total of 586 patients with surgery for primary pilonidal sinus disease were subjected to a telephone interview 7-25 years after surgery to determine 10- and 20 year recurrence rate using Kaplan Meier Statistics. RESULTS: Results show that 546 patients had elective surgery showing a recurrence rate of 23.1% (actuarial 10.6-17% after 5-10 years). Forty patients had urgent off-time surgery with crude long-term recurrence rate 30%; actuarial 25.6-28.9% after 5-10 years); P=0.028; logrank. Mind bogglingly, Methylene blue application was dramatically reduced in the urgent group compared to the elective group, although Methylene blue is known to halve recurrence rate. CONCLUSION: Surgical craftsmanship quality was identical in elective and urgent pilonidal sinus surgery with comparable long-term recurrence rate. Decision making was markedly biased in urgent off-time pilonidal sinus surgery, counteracting the good long-term recurrence rate enabled by proper surgical craftsmanship.

A rare vasoproliferative lesion: angiolymphoid hyperplasia with eosinophilia of the hand.

Angiolymphoid hyperplasia with eosinophilia (ALHE) is a rare vasoproliferative lesion of uncertain aetiology, involving the skin and subcutaneous tissue. The predilection of the tumour-like lesion is for the head and neck region. Radical surgical excision is still regarded as the most effective treatment. We present the case of a 33-year-old female with ALHE of the right hand. Preoperative MRI and angiography demonstrated involvement of the fourth and fifth rays, with complete occlusion of the ulnar artery, and a small lesion at the level of the metacarpophalangeal joint of the index finger. Complete tumour excision could not be achieved without resection of the fourth and fifth rays. One year postoperatively, there were no clinical signs of recurrence. The patient refused any further invasive diagnostic and follow-up examinations. Angiolymphoid hyperplasia of the hand is a rare disease, and patients should undergo early surgical treatment to achieve complete excision of the lesion.

[Finger replantation in a 3-year-old child]. / Erfolgreiche Replantation nach distaler Fingeramputation bei einem dreijährigen Kind.

In this case report, we present a three year old boy who suffered an amputation of his left index finger at the level of the nail base (proximal zone I) caused by a scissor cut. Following referral to a center with hand surgical and pediatric care, successful replantation was achieved and postoperative pediatric care ensured finger perfusion. Three months postop, the reconstructed finger was in normal daily use with full function. Our success encourages for initial replantation of digits in infants in any case and irrespective of the level of amputation. Optimal results in these patients can only be achieved by interdisciplinary care of hand surgeons and pediatricians.

Computer-guided microsurgery: surgical evaluation of a telerobotic arm.

A new telerobotic arm was evaluated in different microsurgical procedures. The system consisted of a robotic arm bearing a microsurgical forceps controlled by a joystick-like master unit operated by the surgeon's hand. The robotic arm functioned as an operating as well as assisting instrument. Advantages of the system were its precise functioning, which was especially important when tissue or instruments had to be held for a longer period of time, as well as its ability to replace an assisting person to some extent. Deficiencies of the system were its 10-min startup, the spatial conflict with in the operative field, and the poor rotation of the robotic tip. In some procedures, the telerobotic arm could replace the standard microsurgical instrument guided by the surgeon's second hand; in other maneuvers it could function as the surgeon's third hand with precision and void of tremor.

Modified dorsalis pedis flap for coverage of a pretibial pressure sore after hip rotationplasty.

Rotationplasty is a well-established procedure after total femur resection, especially in children. Rehabilitation is superior to disarticulation of the hip or hemipelvectomy because patients regain hip and knee function.(1) A tight fit of the prosthetic shaft is essential. The pretibial area has a low physiological resistance to pressure and shear forces, and is thus at increased risk of developing pressure-related complications. Skin defects with exposure of skeletal elements require flap coverage. The dorsalis pedis flap is one of the surgical options available for skin coverage of the proximal anterior leg. It can be rotated to cover almost any site on the anterior aspect of the leg if the pedicle is mobilised up to the anterior tibial artery.(2)Since donor site complications are common, this flap has few indications.(3)

[Improving microcirculation of muscle flaps by tissue plasminogen activator in the rat cremaster muscle flap model]. / Verbesserung der Mikrozirkulation von Muskellappen durch Gewebsplasminogenaktivator im Ratten-Cremaster-Muskellappenmodell.

Currently, tissue-plasminogen activator (t-PA) is the most potent and nevertheless safe fibrinolytic in clinical use. Its indications are fibrinolysis in acute myocardial infarction, ischemic stroke, deep vein thrombosis, pulmonary thromboembolism, as well as different kinds of peripheral arterial embolism. However, controlled studies on the effect of t-PA in microsurgery and free tissue transplantation are lacking. This study was designed to evaluate the effect of tissue-plasminogen activator on skeletal muscle flap perfusion after a thrombogenic stimulus. 24 male Sprague-Dawley rats were divided into four experimental groups of six animals each. In group 1, the cremaster was isolated as an end organ flap, in group 2 after cremaster isolation a semicircular inverted suture as a thrombogenic insult was performed at the ipsilateral common iliac artery. In group 3, local t-PA infusion followed the inverted suture and in group 4, vehicle was infused. After 24 hours, we measured cremaster muscle flap hemodynamics using intravital microscopy. Capillary perfusion significantly decreased after the inverted suture from 6.23 (group 1) to 1.50 (group 2) functional capillaries per visual field (medians). t-PA significantly increased capillary perfusion after the thrombogenic insult from 1.50 (group 2) and 2.50 (group 4) to 6.00 (group 3) (medians). Restoring capillary perfusion after a thrombogenic insult t-PA may increase flap survival rates.

[A model for allogenic extremity transplantation in the rat with possible microcirculatory monitoring]. / Modell zur allogenen Extremitätentransplantation der Ratte mit Möglichkeit des mikrozirkulatorischen Monitoring.

A rat model for monitoring allograft rejection of transplanted rat hindlimbs at the microcirculatory level is described. The well-established rat cremaster flap model is combined with a rat hindlimb transplantation procedure at a level proximal to the neurovascular pedicle of the cremaster muscle. The cremaster serves as a microcirculatory monitor for in vivo evaluation of graft rejection by measuring skeletal muscle perfusion. Donor animals are male Lewis Brown Norway rats and recipients are Lewis rats. The right cremaster muscle of the donor animal is dissected as a tubular island flap and preserved in a subcutaneous tunnel in the hindlimb. Afterwards, the right hindlimb including the cremaster is amputated at the mid level of the common iliac vessels and transplanted to the recipient at the level of the external iliac vessels. Over a time period of five days, the cremaster muscle of the composite transplants showed appropriate tissue quality for intravital microscopical observations. This transplantation model allows evaluation of allograft rejection in vivo at the microcirculatory level.

Arterial crush injury causes decrease in tissue perfusion at the level of the microcirculation in skeletal muscle flap.

This study was designed to evaluate the effects of crush injuries to the feeding arteries of a muscle flap on microcirculatory haemodynamics. Eighteen male Sprague-Dawley rats were divided into three experimental groups for intravital microscopy of the cremaster muscle flap. Group 1 served as control. In group 2 the common iliac artery and in group 3 additionally the lower abdominal aorta was crushed with a Kocher clamp (17.4 N) over 5 min. Microcirculatory parameters (red blood cell velocity, vessel diameter, and capillary perfusion) were monitored before and 2 h after crush. In the one-level crush group, red blood cell velocities significantly decreased by 39.17% (P=0.046) in first order arterioles and by 32. 91% (P=0.0106) in second order arterioles. In capillary perfusion, a drop of 48.02% (P=0.0039) was noted. In the two-level crush group, red blood cell velocities significantly dropped over 32.06% (P=0. 0250) in first order arterioles, 35.91% (P=0.0065) in second order arterioles, and 45.69% (P=0.0782) in first order venules. Capillary perfusion was reduced by 20.16% (P=0.374). Arterial crush injuries as possible thrombogenic insults may result in a significant decrease in skeletal muscle perfusion although the blood supply through the crushed supplying vessel is maintained.

Failure in developing a model for complete vascular thrombosis in the common iliac artery in the rat.

The purpose of this study was to develop a model for complete arterial thrombosis proximal to the rat cremaster flap for subsequent fibrinolytic studies at the microcirculatory level. We divided 20 male Sprague-Dawley rats into four experimental groups of five animals each. We assigned each group to an established thrombosis model using crush and standard microsurgical anastomosis, crush and intimal abrasion, inverted arterial suture, and intravascular silk sutures combined with microsurgical anastomosis at the common iliac artery. Vessel patency was examined using the milking test 30, 60, 90, and 120 min after the thrombogenic insults. The model of perpendicular silk sutures and anastomosis caused complete arterial thrombosis in one animal over 120 min. The other models failed in all animals. In conclusion, the thrombogenic models used in this study are not capable of creating a reliable complete arterial thrombosis in the common iliac artery of the rat.

[Applicability of the robot arm for microsurgical operations]. / Verwendbarkeit eines Roboterarmes für mikrochirurgische Operationen.

In this project, we evaluated a new robotic arm, RAMS (Robot Assisted Microsurgery) Workstation, for microsurgical procedures. We assigned seven microsurgical tasks to the robotic arm to investigate its capabilities and limitations during microsurgery. The robotic arm was able to function as the primary operating tool in removal of foreign bodies and thrombi as well as in intravascular positioning and holding of needles and catheters. The robot worked with great precision and without vibration. It served as an assisting tool in vessel dissection, ligation of side branches, and microsurgical anastomosis. The main drawbacks include a long warm-up period, the large size, poor rotation of the tip of the robotic arm, and frequent unintended shut-downs. The RAMS Workstation is a precise tool and can assist the surgeon as a "second" or "third hand". It cannot entirely replace the microsurgical instruments held by the surgeon.

Tissue-plasminogen activator restores muscle flap perfusion in the rat.

This study was designed to evaluate the effect of tissue-plasminogen activator on skeletal muscle flap perfusion after a thrombogenic insult. Twenty-four male Sprague-Dawley rats were divided into 4 experimental groups of 6 animals each. In group 1 (sham), the cremaster muscle was isolated as an end-organ flap. In group 2, after cremaster muscle isolation, a semicircular inverted suture as a thrombogenic insult was performed at the ipsilateral common iliac artery. In group 3, local tissue-plasminogen activator infusion followed the inverted suture. In group 4, vehicle was infused. After 24 hours, the cremaster muscle flap hemodynamics and leukocyte-endothelial interactions were measured using intravital microscopy. Capillary perfusion significantly decreased after the inverted suture from a median of 6.23 (group 1) to 1.50 (group 2) functional capillaries per visual field. Tissue-plasminogen activator significantly increased capillary perfusion after the thrombogenic insult from a median of 1.50 (group 2) and 2.50 (group 4) to 6.00 (group 3). Tissue-plasminogen activator restored capillary perfusion after a thrombogenic insult to the main feeding artery.

Effects of 8-Gy radiation on the microcirculation of muscle flaps in the rat.

Combination of radical excision and radiation has been used as a treatment modality for cancer patients. As a result, in reconstructive surgery there is often a need to harvest flaps in the vicinity of previously irradiated tissues. Radiation has been shown to cause progressive injury to the macrocirculation and microcirculation, often jeopardizing flap survival. The purpose of this study was to examine whether radiation significantly affects the sequence of leukocyte-endothelial interactions or the hemodynamics of the muscle flap in both acute and chronic situations. Male Sprague-Dawley rats (n = 42) were divided into seven groups of six rats each. Rats in group I were not irradiated. Groups II through VII received 8-Gy radiation to the right groin and scrotum. Groups II, III, and IV were examined at 4, 24 and 72 hours, respectively, and groups V, VI, and VII were examined at 1, 2 and 12 weeks. For intravital microscopy, the cremaster muscle was dissected on its neurovascular pedicle. Vessel diameters and red blood cell velocities were measured in the central cremasteric branches and branch arterioles. Capillary perfusion was evaluated in 27 visual fields of each flap. Leukocyte-endothelial interactions were evaluated by numbers of rolling, adhering, and transmigrating leukocytes in post-capillary venules. In the same postcapillary venule, we measured the endothelial edema index (constriction index). The hemodynamics of irradiated flaps did not differ significantly from those of controls. Diameter and red blood cell velocity were increased in the first- and second-order arterioles and were highest at 72 hours and 1 week. After irradiation, third-order arterioles were constricted. Radiation reduced capillary perfusion by 4.3, percent. None of the differences were statistically significant. Neither leukocyte behavior nor the constriction indices differed among the groups. In conclusion, low-dose radiation of 8 Gy does not affect hemodynamics or leukocyte-endothelial interactions of muscle flaps in the rat. Muscle tissue with intact microvasculature can be harvested for reconstructive procedures after low-dose radiation.

[Morphological aspects of load bearing of the wrist joint after midcarpal partial arthrodesis]. / Morphologische Aspekte der Beanspruchung des Handgelenks nach mediokarpaler Teilarthrodese.

Midcarpal fusion is a reliable treatment for advanced carpal collapse following scaphoid nonunion or scapholunate dissociation. It remains, however, unclear if the alignment of the fused carpal bones influences the redirection of load towards the lunate. The objective of this study was to assess the actual loading conditions after midcarpal fusion in patients by evaluating the patterns of subchondral bone mineralization in the distal articular surface of the radius. Nine patients, who were treated by midcarpal fusion with complete excision of the scaphoid, were examined after an average of 22 months postoperatively by means of CT osteoabsorptiometry. All patients showed peak mineralization in the lunate fossa of the distal articular surface of the radius. Six patients with correct carpal alignment had one large density maximum in the lunate fossa and none in the scaphoid fossa. Patients with incomplete correction of the radial translocation of the capitate, incomplete excision of the scaphoid, or incomplete correction of the extension position of the lunate, showed a second density maximum in the scaphoid fossa. These findings emphasize that a correct carpal alignment is necessary to achieve a complete unloading of the degeneratively altered scaphoid fossa.

Thrombogenic stimulus causes long-term decrease of muscle flap perfusion.

This study was designed to evaluate the effect of a continuous thrombogenic insult at the feeding artery on skeletal muscle flap perfusion over 24 hours. Twelve male Sprague-Dawley rats were divided into two experimental groups. In the control group (N = 6) and in the treatment group (N = 6) the right cremaster muscle was isolated on its neurovascular pedicle and the tubular muscle flap was preserved in the medial part of the hind limb over a 24-hour period for subsequent microcirculatory observation. In the treatment group, an inverting suture was applied over half of the circumference of the ipsilateral common iliac artery to create a continuous thrombogenic stimulus. Intravital microcirculatory measurements obtained were red blood cell velocities, vessel diameters, capillary perfusion, endothelial edema index, and leukocytic-endothelial interactions. There were no statistically significant differences seen in red blood cell velocities, vessel diameters, and leukocytic-endothelial interactions between the groups. However, the inverting suture caused a significant drop in capillary perfusion from 6.23 to 1.50 capillaries per visual field (median; p = 0.002). An arterial thrombogenic insult may result in a significant decrease in capillary perfusion in muscle flaps over 24 hours although the blood flow through the thrombogenic main feeding vessel is maintained.

Patterns of subchondral bone mineralization in the wrist after midcarpal fusion.

Midcarpal fusion represents a salvage procedure in cases of advanced carpal collapse, which unloads the scaphoid compartment and redirects the load to the intact lunate compartment of the radiocarpal joint. The aim of this study was to obtain further information about the loading conditions in the living subject by evaluating the pattern of subchondral bone mineralization in patients who have undergone midcarpal fusion of the wrist. Between 4 and 42 months after the surgery, 9 male patients were examined by means of computed tomographic osteoabsorptiometry. All of them showed peak mineralization in the lunate fossa of the radius. Six patients had only one large density maximum in this fossa and no corresponding maximum in the scaphoid fossa. In accordance with our expectations, loading after midcarpal fusion was found to be transmitted mainly through the lunate compartment, a result that was observed even after as little as 4 months, and that thus confirmed subchondral bone mineralization as a valuable parameter for assessment of long-term stress distribution.

Effect of tissue-plasminogen activator on leukocyte-endothelial interactions at the microcirculatory level.

In free tissue transfer and replantation surgery, there is a debate over whether any pharmacologic agents should be used to improve vessel patency and tissue survival. Because tissue-plasminogen activator (t-PA) is a highly effective and safe fibrinolytic, it may be useful in obtaining and maintaining vessel patency. The direct effects of t-PA on skeletal muscle hemodynamics and leukocyte activation at the microcirculatory level were investigated. Male Sprague-Dawley rats (n = 20) were divided into three experimental groups: control (n = 8), vehicle (n = 6), and t-PA (n = 6). Using the cremaster muscle flap model and intravital microscopy, red blood cell velocity, vessel diameter, capillary perfusion, endothelial edema index, and leukocyte-endothelial interactions (rolling, adhering, and transmigrating leukocytes) in postcapillary venules were measured. In the vehicle and t-PA groups, vehicle or t-PA was infused by means of a catheter inserted into the lower abdominal aorta for local infusion. Except for a significant reduction in the diameter of the first order arterioles from 117 microm to 82 microm (medians; p = 0.026), t-PA did not significantly affect red blood cell velocity, vessel diameter, or capillary perfusion compared with vehicle. However, leukocyte-endothelial interactions did differ significantly in postcapillary venules. Adhering leukocytes counted per visual field decreased from 4.67 in the vehicle group and 3.50 in the control group to 1.67 in the t-PA group (medians; p = 0.015 and p = 0.005, respectively); transmigrating leukocytes in the t-PA group decreased from 4.75 in the vehicle group and 3.50 in the control group to 1.67 in the t-PA group (medians; p = 0.002 and p = 0.043, respectively). t-PA treatment significantly decreased the number of both adhering and transmigrating leukocytes. These novel findings on leukocyte-endothelial interactions suggest that t-PA has anti-inflammatory effect.

[Post-traumatic carpal collapse (SLAC- and SNAC-wrist)--stage classification and therapeutic possibilities]. / Der posttraumatische karpale Kollaps (SLAC- und SNAC-wrist)--Stadieneinteilung und therapeutische Möglichkeiten.

Longstanding scaphoid nonunion or scapholunate ligament injuries can lead to carpal collapse. SLAC-wrist (scapholunate advanced collapse) following scapholunate dissociation and SNAC-wrist (scaphoid nonunion advanced collapse) after missed fusion of scaphoid fracture should be differentiated. Severity of degenerative changes is classified by three stages. In stage I where arthrosis is limited to the radial styloid reconstructive procedures of the scaphoid or scapholunate ligament are the treatment of choice. In stage II including arthrosis of the radioscaphoid joint and stage III with additional arthrosis in the midcarpal joint these procedures are excluded. Salvage procedures preserving wrist mobility like midcarpal fusion or proximal row carpectomy are preferable to total wrist fusion which represents the last line of defence.