Bernd Fink

Osteoneogenesis and its influencing factors during treatment with the Ilizarov method

The radiographs of 57 patients who had undergone 58 callus distractions and 13 epiphyseal distractions were evaluated. During the course of treatment, the density of the distraction areas on radiographs was measured in total and along the medial, lateral, ventral, and dorsal margins using a digital radiograph processing system. The densities of the whole distraction length were correlated to the following parameters: age of patient, start of distraction after corticotomy, mean distraction speed, mean amount of weight load during the period of distraction and consolidation, location of corticotomy (distal femoral metaphysis versus the proximal tibial one), and diclofenac medication. Except for the location of corticotomy and the diclofenac medication, the density was influenced by all these parameters. Age of the patient and weight load were the most important parameters. Patients with leg shortening caused by poliomyelitis and a patient with a shortened leg after amniotic strangulation showed a slower rise of the density trend curve on radiographs than the other patients. When comparing the different regional density curves, a significant gradual density decrease could be observed from the medial to the lateral side in the femur, from lateral to medial in the tibia, and from the dorsal to the ventral side in both bones. The respective differences between lateral and medial density, and between dorsal and ventral density, were significantly higher in cases of callus distraction than in cases in which epiphyseal distraction had been used. The amount of bone regeneration varied regionally primarily because of the inhomogeneous soft tissue covering of the bone and the impairment of its local blood supply by the surgical exposure for the corticotomy. The clinical relevancy of the various parameters for osteoneogenesis is discussed in this article.

Periprosthetic fractures of the femur associated with hip arthroplasty

The nature of the treatment of periprosthetic fractures depends on the localisation, the stability of the prosthesis and the condition of the bone. The Vancouver fracture classification has proved to be of value in determining specific modes of treatment. The current review analyses the different therapeutic options resulting in a concept of fracture-specific treatment. In this report we propose an extended version of this classification in which periprosthetic fractures associated with endoprostheses anchored in the epiphysis or metaphysis, as well as interprosthetic fractures, are taken into consideration.

Holmium: YAG Laser—induced aseptic bone necroses of the femoral condyle

In laser-controlled cartilage-ablation arthroplasties, the attention focuses more and more on the depth effects of the various lasers, especially as heat necroses of the cartilage and even in places of the bone were found in animal experiments. For the first time, two cases of holmium: YAG laser-induced aseptic bone necrosis of the femoral condyles after cartilage ablation are described.

Hip revision arthroplasty in periprosthetic fractures of vancouver type B2 and B3.

Objectives The purpose of the study was to test the hypothesis that stem revision in Vancouver Type B2 and B3 periprosthetic fractures using a transfemoral surgical approach and a modular, noncemented, tapered and fluted revision stem led to reproducibly good results with respect to fracture healing, stability of the prosthesis stem, dislocation, intraoperative fracture, and clinical outcome. Design Prospective study. Setting Orthopaedic specialized clinic and center for joint replacement. Patients Twenty-two patients with periprosthetic fractures of Vancouver Type B2 and 10 of Type B3 were followed of at least 24 months. Main Outcome Measure Fracture healing, stability of the prosthesis stem, complications, and clinical outcome. Results All fractures healed with a mean time of 14.5 ± 5.2 weeks. No cases of subsidence of the stem were observed and, according to the classification of Engh et al concerning the biologic fixation of the stem, there was bony ingrowth fixation in 28 cases and stable fibrous fixation in four cases. One dislocation occurred and there were no cases of intraoperative fracture. The Harris hip score rose continually after the operations; from a score 3-months postoperatively of 59.2 ± 14.6 points, it rose to 81.6 ± 16.5 points after 24 months. According to the classification of Beals and Tower, all results were rated as excellent. Conclusions The methods described here for stem revision lead to reproducibly good results in the treatment of periprosthetic hip fractures of Vancouver Types B2 and B3. Level of Evidence Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Changes in canine skeletal muscles during experimental tibial lengthening.

In 24 beagles, lengthening of the right tibia was performed by callus distraction after osteotomy and application of a ring fixator. Distraction was started at the fifth postoperative day, with a distraction rate of 0.5 mm twice per day, and ended after 25 days. A control group of six additional dogs underwent tibial osteotomy and external fixation without distraction. Twelve animals with and three animals without leg lengthening were euthanized immediately after the distraction period of 25 days (Group A); the remaining 15 dogs were euthanized after an additional consolidation phase of another 25 days (Group B). From the distracted right leg and from the left control leg the tibialis anterior muscle, extensor digitorum longus muscle, peroneus longus muscle, and gastrocnemius muscle were removed and studied by means of routine histologic, histochemical, and immunohistochemical analyses, and electron microscopic examination. The muscles of the control group showed no differences between the right and left sides. However, in the other 24 dogs of Groups A and B, the authors saw marked alterations affecting only the lengthened muscles but not the muscles of the control limbs. These changes were highly significant and included muscle fiber degeneration and regeneration, target fibers, central cores, minicores, marked endomysial and perimysial fibrosis, and atrophy of Type 1 and Type 2 fibers. In the consolidation period (Group B) fiber type grouping indicated that reinnervation had occurred. In addition, an increase in satellite cells and myoblasts and proliferation of nuclei were observed. The findings of the current study indicate that leg lengthening results not only in muscle fiber degeneration followed by regeneration and reinnervation but also in formation of new muscle tissue.

Comparison of a minimally invasive posterior approach and the standard posterior approach for total hip arthroplasty A prospective and comparative study

BackgroundIt is not clear whether total hip arthroplasty performed via a minimally invasive approach leads to less muscle trauma compared to the standard approach.Materials and methodsTo investigate whether a minimally invasive posterior approach for total hip arthroplasty results in lower levels of muscle-derived enzymes and better post-operative clinical results than those obtained with the standard posterolateral approach fifty patients in both groups were compared in a prospective and comparative study. The following parameters were examined: muscle-derived enzymes CPK, CK-MM and myoglobin pre-operatively, 24 and 48 hours post-operatively, CRP and hemoglobin on the third postoperative day, loss of blood, daily pain levels, the rate of recovery (time taken to attain predefined functional parameters), the Oxford Hip Score, the SF-36 score and the WOMAC score pre-operatively and six weeks post-surgery, the position of the implant and the cement coating by post-operative X-ray examination.Results and ConclusionsThe minimally invasive operated patients exhibited a significantly lower loss of blood, significantly less pain at rest and a faster rate of recovery but the clinical chemistry values and the other clinical parameters were comparable.

The DUROM Cup Humeral Surface Replacement in Patients with Rheumatoid Arthritis

BACKGROUND Rheumatoid arthritis often leads to severe destruction of the glenohumeral joint, including synovitis and inflammation-induced alterations of the rotator cuff. Cup arthroplasty, or surface replacement of the shoulder, was introduced in the 1980s. The aim of this study was to evaluate the midterm results of the DUROM cup surface replacement for patients with rheumatoid arthritis affecting the glenohumeral joint. METHODS From 1997 to 2000, forty-two DUROM cup hemiprostheses were implanted in a cohort of thirty-five patients (forty-two shoulders), who were evaluated preoperatively and again at three, twelve, and more than sixty months postoperatively. Six patients (seven shoulders) were lost to follow-up. Thirty-five shoulders in twenty-nine patients (twenty-one women and eight men with an average age of 61.4 years) could be evaluated prospectively after an average follow-up period of 73.1 months. Patients were evaluated clinically with the use of the Constant score, and a detailed radiographic analysis was performed to determine the presence of endoprosthetic loosening, glenohumeral subluxation, and glenoid bone loss. RESULTS The mean Constant score for the thirty-five shoulders increased from 20.8 points preoperatively to 64.3 points at a mean of 73.1 months postoperatively. There were three revisions: one to replace an implant that was too large, another to treat glenoid erosion, and a third due to loosening of the implant. No additional cases of loosening of the prosthesis or changes in cup position were observed radiographically. Over the five-year follow-up period, proximal migration of the cup increased in 63% of the shoulders, and glenoid depth increased in 31%. With the numbers studied, no differences in clinical outcome were identified between patients with a massive rotator cuff tear and those with a smaller or no tear. CONCLUSIONS The midterm results of the cemented DUROM cup surface replacement for patients with advanced rheumatoid arthritis of the shoulder are very encouraging, even for patients with a massive tear of the rotator cuff. The advantage of this cup arthroplasty is the less complex bone-sparing surgery. In the event of failure of the implant, other reliable salvage options remain available.

Distal Interlocking Screws With a Modular Revision Stem for Revision Total Hip Arthroplasty in Severe Bone Defects

A prospective study of 15 patients was designed to examine whether the modular cementless revision stem (Revitan curved; Zimmer GmbH, Winterthur, Switzerland) is suitable for stem revisions with a defective isthmus when distal interlocking screws are also used for fixation. During a follow-up period of 35.4 +/- 11.4 months (24-70 months), there was one stem loosening with screw breakage in a case of a stem that was too thin. According to Engh et al, bony ingrowth fixation of the stem occurred in 12 cases and stable fibrous fixation in 2 cases. The Harris Hip Score rose continuously from 44.7 +/- 12.9 points preoperatively to 75 +/- 10 points at 24 months. This concept of additional stem fixation with distal interlocking screws represents a useful treatment option for revision arthroplasty in rare cases of a defective isthmus.

Bilaterally increased VEGF-levels in muscles during experimental unilateral callus distraction

Angiogenesis is essential for wound healing and proliferative processes such as bone formation and repair. Since increased expression of the vascular endothelial growth factor (VEGF) stimulates bone formation, it can be hypothesized that surgical procedures leading to a systemic increase of VEGF for instance during wound healing, influence enchondral ossification processes and might be responsible for observed growth phenomena during callus distraction. To study the mechanisms of angiogenesis in soft tissue during unilateral callus distraction, lengthening of the right tibia was performed in 12 beagles. After osteotomy, application of a ring fixator and after five latency days, distraction was started for 25 days. A control group of four additional beagles underwent no surgical procedure. Subsequent to the distraction period (Group A), muscle samples from six beagles were taken from the distracted side (ds) and the contralateral non‐distracted side (n‐ds), six beagles underwent an additional consolidation period of 25 days (Group B). Samples were analyzed for VEGF, VEGFR‐1 and VEGFR‐2 mRNA expression using real‐time PCR and protein expression using Western Blot analysis. Muscles from both extremities showed significantly increased expression of VEGF and its cognate receptors VEGFR‐½. Expression decreased significantly after the consolidation period, whereby the level at the non‐distracted side decreased more than the level at the distracted side. Interestingly VEGF and VEGFR‐1 levels at the non‐distracted side were significantly higher than at the distracted side. In contrast VEGFR‐2, the receptor that mediates endothelial cell proliferation, showed higher levels at the distracted than at the non‐distracted side. These findings indicate that callus distraction results not only in locally increased expression of VEGF and its receptors, but leads also to increased VEGF and VEGFR‐½ levels at distant sides and might therefore be responsible for the observed growth phenomena during callus distraction.

Early detection of avascular necrosis of the femoral head following renal transplantation

This prospective study included 43 patients undergoing renal transplantations. Magnetic resonance imaging (MRI) and X-rays of the hip joints were produced 3 and 12 months after transplantation. In 6 hip joints of 4 patients (9.3%), we discovered femoral head necroses just 3 months after transplantation. Three of the hip joints affected were symptomatic and 3 painless. The MR images taken 12 months after transplantation revealed no additional femoral head necrosis. A core decompression was performed on 3 joints. In contrast to those with core decompression, the femoral heads without core decompression showed a progression of the necrosis in 2 of 3 cases. All 4 patients with femoral head necroses were younger than 50 years and exhibited a premature conversion of the haematopoietic marrow to fatty marrow in the area of the proximal femoral metaphysis. A similar premature conversion to fatty marrow was seen in 6 of the 22 (27.2%) patients younger than 50 years and without femoral head necroses. The doses in long-term steroid medication and the steroid doses during the rejection periods of the patients with femoral head necroses were not significantly higher than those for the patients with premature conversion to fatty marrow. The latter had also not received significantly higher doses than the patients whose MRI findings were inconspicuous.