Improved oxygenation in ischemic hamster flap tissue is correlated with increasing hemodilution with Hb vesicles and their O2 affinity.

The aim of this study was to test the influence of oxygen affinity of Hb vesicles (HbVs) and level of blood exchange on the oxygenation in collateralized, ischemic, and hypoxic hamster flap tissue during normovolemic hemodilution. Microhemodynamics were investigated with intravital microscopy. Tissue Po2 was measured with Clark-type microprobes.

Reperfusion injury in free bone grafts after tourniquet-induced ischemia.

For successful revascularization, incorporation, and survival of fracture fragments or free nonpedicled bone grafts, the first days after surgery seem to be most critical. Using intravital fluorescence microscopy, the effects of 3 hours of tourniquet-induced ischemia were assessed on newly formed angiogenic microvessels 4, 8, and 12 days after isogeneic transplantation of metatarsal bones into dorsal skin fold chambers of adult inbred C57BL/6 mice. The microvascular perfusion index of newly formed microvessels was quantified 30 and 120 minutes after initiation of reperfusion.

Normovolemic hemodilution with Hb vesicle solution attenuates hypoxia in ischemic hamster flap tissue.

The aim of this study was to test whether oxygenation in acutely ischemic, collateralized tissue may be improved by normovolemic hemodilution with a solution containing liposome-encapsulated human Hb (HbV). A skin flap model in anesthetized hamsters was used, which consisted of two parts receiving either anatomic or collateral perfusion. Microhemodynamics were investigated with intravital microscopy.

[Early damage to the acetabular cartilage in slipped capital femoral epiphysis. Therapeutic consequences].

Epiphyseolysis capitis femoris represents the most common disorder of the adolescent hip, which is followed by a significant rate of early osteoarthrosis. Based on intraoperative findings during the surgical management of 23 hips with epiphyseolysis, early acetabular cartilage abrasion by a cam effect and acetabular rim impingement elicited by the prominent femoral metaphysis have been identified. Both phenomena cause direct damage to the hip joint, especially during flexion and flexion/internal rotation of the hip.

Cryopreservation of osteochondral allografts: dimethyl sulfoxide promotes angiogenesis and immune tolerance in mice.

Background: Although transplantation of cryopreserved bone allografts has become a routine procedure in orthopaedic surgery, biological and immunological impairment remains an unsolved problem that causes clinical failures. Experimental and clinical evidence has indicated that bone grafts that are revascularized early remain viable and contribute to union at the recipient site. Unprotected cryopreservation, used in most bone banks to reduce graft antigenicity, is associated with complete loss of graft viability, potentially contributing to graft failure.

Fatal retroperitoneal hemorrhage caused by perforation of a guidewire pin for proximal femur fixation.

A 77-year-old woman with a slightly displaced intertrochanteric two-fragment fracture of the left hip was treated by internal fixation using a screw-nail device (gamma nail). After the operation she became hemodynamically unstable, and ultrasound revealed a large retroperitoneal fluid accumulation in the left lower abdomen. A contrast computed tomogram revealed active hemorrhage next to the quadrilateral surface of the left acetabulum.

[MR-Arthrography with radial sequences for visualization of early hip pathology not visible on plain radiographs].

Aim: We wanted to improve MRI visualization of early hip pathology invisible on plain radiographs.

Method: An MR arthrography of the hip with radial sequences is described. The standard MR technique is improved by 1) using a small flexible surface coil to show selectively the hip joint to be examined, 2) application of gadolinium intra-articularly and 3) by radial imaging sequences perpendicular to the true plane of the acetabulum.

Early lesions of the labrum and acetabular cartilage in osteonecrosis of the femoral head.

Osteonecrosis of the femoral head can be caused by a variety of disorders and affects the relatively young patient. Most studies have concentrated on the femoral changes; the sites of early lesions of the labrum and acetabular cartilage have not been recorded. We studied 17 hips with osteonecrosis and a wide congruent joint space on radiographs and by direct inspection of the femoral head, labrum and acetabular cartilage during surgery.

Surgical landmarks to determine humeral head retrotorsion for hemiarthroplasty in fractures.

Malrotation has been suggested as a cause of failure of hemiarthroplasty of the proximal humerus. Placing a shoulder prosthesis in relationship to the bicipital groove might reproduce individual anatomy more reliably than using a standardized retrotorsion. The purpose of this study was to determine criteria for accurate adjustment of retrotorsion even when the proximal bicipital groove is destroyed, as is the case in fractures.

Entry point soft tissue damage in antegrade femoral nailing: a cadaver study.

Introduction: Little attention is paid to insertion site morbidity associated with antegrade femoral nailing. However, residual peritrochanteric pain after nailing is not uncommon. Additionally, the end branches of the medial femoral circumflex artery (m.

Rationale of periacetabular osteotomy and background work.

The Bernese periacetabular osteotomy is a joint-preserving procedure used after growth plate closure to correct acetabular coverage and stabilize the femoral head. The polygonal, juxta-articular osteotomy respects the vascular blood supply to the acetabular fragment and facilitates an extensive acetabular reorientation. It achieves improvement of the insufficient coverage of the femoral head, reduction of mediolateral displacement, and correction of the version of the fragment.

Gluteus minimus-induced femoral head deformation in dysplasia of the hip.

Lateral notching of the femoral head is considered pathognomonic for spastic subluxation of the hip. Less frequently, flattening is seen with extrusion of the femoral head in nonspastic hip dysplasia. The aim of this study was to throw light on its underlying pathomechanism.

Femoroacetabular impingement and the cam-effect. A MRI-based quantitative anatomical study of the femoral head-neck offset.

We have observed damage to the labrum as a result of repetitive acetabular impingement in non-dysplastic hips, in which the femoral neck appears to abut against the acetabular labrum and a non-spherical femoral head to press against the labrum and adjacent cartilage. In both mechanisms anatomical variations of the proximal femur may be a factor. We have measured the orientation of the femoral neck and the offset of the head at various circumferential positions, using MRI data from volunteers with no osteoarthritic changes on standard radiographs.

[Inadequate detectability of early stages of coxarthrosis with conventional roentgen images].

Aim: The study was undertaken to determine the value of standard radiographs in the early stages of osteoarthritis.

Methods: Standard radiographs and arthro-MRI's from thirty hips operated on for early arthrosis (age 25-57 years) were independently analyzed by two orthopaedic surgeons and one radiologist blinded from the intra-operative findings. The radiographs were read on two occasions two months apart.

Free nerve endings in the ligamentum capitis femoris.

We report the presence of free nerve endings (FNE) in the ligamentum capitis femoris (LCF). Qualitative and quantitative measurements on the incidence of FNE, as assessed by immuno-histochemistry for the S-100 protein, were obtained from 18 patients undergoing hip surgery. We found FNE in all LCF, with no association to age.

Development of transplanted fetal bones: differences between isografts and allografts in mice.

Allogeneic bone from bone banks frequently is used when large skeletal defects have to be bridged in orthopaedic surgery. Beside immunologic rejection of the graft, the loss in osteogenic potential caused by bone banking procedures may be a major reason for limited clinical success. Similar problems as described for bone have occurred with cartilage and osteochondral transplants.

Dorsal skinfold chamber preparation in mice : studying angiogenesis by intravital microscopy.

Since 1924, when the first transparent chamber model in animals was introduced by Sandison (1), many other chamber models have been described in the literature for studying angiogenesis and microcirculation in a wide variety of neoplastic and nonneoplastic tissues by means of intravital microscopy (for reviews see 2-4). Because angiogenesis is an active and dynamic process, one of the major strengths of chamber models is the possibility of monitoring angiogenesis in vivo continuously up to several weeks with high spatial and temporal resolution. In addition, after the termination of experiments, tissue samples can be excised easily and further examined by various in vitro methods (e.

Slipped capital femoral epiphysis: early mechanical damage to the acetabular cartilage by a prominent femoral metaphysis.

On the basis of intraoperative observations in 13 consecutive adolescents (14 hips) with slipped capital femoral epiphysis (SCFE), we found that when the anterior femoral metaphysis was level with or extended past the epiphysis, it caused labrum and cartilage damage. As a result of an impingement between the metaphysis and the superomedial acetabular rim, the labrum revealed erosions, scars or tears. Further jamming of the metaphysis into the joint damaged the adjacent acetabular cartilage, varying from a partial- to a full-thickness cartilage loss.

The effect of pedicle artery vasospasm on microhemodynamics in anatomically perfused and extended skin flap tissue.

The aim of this study was to evaluate quantitatively the influence of pedicle artery vasospasm on the microcirculation in skin flaps, particularly in the jeopardized extended portions. For this purpose, the hamster island skin flap model was used, which allowed for simultaneous assessment of hemodynamics in both the pedicle artery and the microvasculature of the flap by intravital microscopy. Vasospasm was induced by applying a V3 microvascular clamp for 30 seconds.

The evolution of indirect reduction techniques for the treatment of fractures.

During the last decade, classic AO/ASIF techniques for internal fixation shifted from direct reduction and rigid fixation to biologic internal fixation using indirect reduction techniques. Biologic internal fixation is characterized by the preservation of bone and soft tissue vascularity and relative rather than absolute mechanical stability. Reduction is achieved by using soft tissue traction while obtaining axial and rotational alignment and the correct length.

Quantitative assessment of angiogenesis and osteogenesis after transplantation of bone: comparison of isograft and allograft bone in mice.

We performed a vital microscopic study in mice bearing dorsal skinfold chambers to characterize microvascular perfusion and leukocyte/endothelium interaction and their effects on elongation and mineralization of neonatal isograft and allograft bone. Isograft (C57/BL to C57/BL) and allograft bone (C57/ BL to BALB/C) revascularized simultaneously. However, vascular perfusion and density were lower in allograft bone than in isograft bone.

The connective-tissue envelope in revascularisation of patellar tendon grafts.

Free patellar tendon grafts used for the intra-articular replacement of ruptured anterior cruciate ligaments (ACL) lack perfusion at the time of implantation. The central core of the graft undergoes a process of ischaemic necrosis which may result in failure. Early reperfusion of the graft may diminish the extent of this process.

Targeting HER-2/neu for active-specific immunotherapy in a mouse model of spontaneous breast cancer.

The identification of tumor-associated antigens has led to increased interest in vaccination strategies to treat and/or prevent cancer. This study examined the feasibility of active-specific immunotherapy against the breast-tumor antigen HER-2/neu using a HER-2/neu transgenic (rNeu-TG) mouse model. rNeu-TG mice develop spontaneous breast tumors after pregnancy, indicating that they fail to mount an effective immune response against rNeu.