[Peroneal nerve palsy after total knee arthroplasty under continuous epidural anaesthesia]. / Peronäusläsionen nach KTEP-Implantation unter Verwendung einer postoperativ fortgeführten periduralen Analgesie.

BACKGROUND: Peroneal nerve palsy is a rare but distressing complication of total knee arthroplasty (TKA). After introducing a standardised intraoperative and postoperative epidural anaesthesia protocol under otherwise unchanged perioperative management, we noted a sudden cumulation of peroneal nerve palsies after TKA. PATIENTS AND METHODS: In this retrospective study we checked the patients' histories for well-known risk factors for nerve lesions after TKA as well as for those risk factors controversially discussed in the literature. RESULTS: We found an additive harmful impact of epidural anaesthesia leading to unrecognised pressure on the peroneal nerve, which caused, in combination with a pressure lesion of the pneumatic tourniquet, an axonal lesion in terms of a double-crush syndrome. By lowering the pneumatic tourniquet pressure and carefully positioning the operated leg, we found a clearly reduced risk of nerve lesion while preserving the advantages of epidural anaesthesia for the patient. CONCLUSION: To prevent a peroneal lesion after TKA while using continuous epidural anaesthesia, we strongly recommend limiting the pneumatic tourniquet pressure to 320 mmHg while ensuring pressure-free positioning of the operated leg.

Increased urinary concentration of collagen type II C-telopeptide fragments in patients with osteoarthritis.

OBJECTIVE: Osteoarthritis (OA) is characterized by a progressive degeneration of articular cartilage and loss of joint function. We hypothesized that degradation of articular cartilage results in increased fragmentation of collagen type II. Thus, the concentrations of degradation products of this major cartilage matrix protein may increase in body fluids of patients with OA. METHODS: Monoclonal antibodies specific for a human collagen type II C-telopeptide (CTx-II) fragment were used in an ELISA for quantification of collagen type II fragments in urine. Clinical assessment of 88 patients with advanced OA of either hip or knee and 48 age-matched controls was performed with the Harris hip score, the Merle d'Aubigné score and a knee score. Joint space narrowing and the Kellgren and Lawrence score were assessed as radiological signs of OA. RESULTS: The concentration of CTx-II was significantly higher in OA patients compared with controls (527 vs. 190 ng/mmol, p < 0.001) whether the patients were diagnosed with hip OA (n = 51) or knee OA (n = 37). Mean CTx-II levels were higher in hip OA than in knee OA and a slight increase in levels with age was observed in the controls, but not in OA subjects. CONCLUSION: Elevation of CTx-II in urine of patients with severe OA compared with a control group suggests that collagen type II derived fragments may serve as markers for OA.

A ten- to 15-year follow-up of the cementless spotorno stem.

We followed the first 354 consecutive implantations of a cementless, double-tapered straight femoral stem in 326 patients. Follow-up was at a mean of 12 years (10 to 15). The mean age of the patients was 57 years (13 to 81). At follow-up, 56 patients (59 hips) had died, and eight (eight hips) had been lost to follow-up. Twenty-five hips underwent femoral revision, eight for infection, three for periprosthetic fracture and 14 for aseptic loosening. The overall survival was 92% at 12 years (95% CI 88 to 95). Survival with femoral revision for aseptic loosening as an endpoint was 95% (95% CI 92 to 98). The median Harris hip score at follow-up was 84 points (23 to 100). Radiolucent lines (< 2 mm) in Gruen zones 1 and 7 were present in 38 (16%) and 34 hips (14%), respectively. Radiolucencies in zones 2 to 6 were found in five hips (2%). The results for mid- to long-term survival with this femoral component are encouraging and compare with those achieved in primary cemented total hip arthroplasty. The high rate of loosening of the cup and the high rate of pain are, however, a source of concern.

[Influence of implant position of a hip prosthesis on alignment exemplified by the CLS shaft]. / Einfluss der Implantatposition einer Hüftendoprothese auf die Standzeit am Beispiel des CLS-Schaftes.

We performed a clinical and radiological analysis to evaluate the significance of the stem position of cementless CLS components with respect to function and survival. We used patient material from a multi-center study of 3,732 CLS stems with a mean follow-up of 43 months (range: 12-142 months). The clinical outcome was assessed using Merle D'Aubigné Scores and stem alignment was determined as the deviation of the longitudinal stem axis from the longitudinal femur axis. We found no correlation between stem alignment and function, survival, implant migration or periprosthetic radiolucent lines. In patients with rheumatoid arthritis and hip ankylosis the neutral stem position was less often achieved than in patients with other diagnoses. The results of our study cast doubt on whether the varus position of the femoral component of cementless tapered CLS-type stem designs is as critical as in cemented total hip arthroplasty.

A new animal model of femoral head necrosis induced by intraosseous injection of ethanol.

There is no reliable animal model of the early stages of osteonecrosis of the femoral head (ONFH) for the evaluation of new therapeutic approaches. In this study, we propose a new animal model of femoral head osteonecrosis. Pure ethanol was injected into the centre of the femoral head in adult Merino sheep under fluoroscopic control. After 3, 6 and 12 weeks the animals were killed and the femoral heads were harvested. Microradiographic and histological changes were analysed and recorded. Partial necrosis was documented over a period of 12 weeks in all animals. The appearance of necrosis in combination with intact macrotexture, macrocirculation and joint cartilage is similar to the features described in early ONFH in humans. Due to its efficacy and its similarity to the early stages of ONFH in humans, this model may be suitable to evaluate new therapeutic techniques in the treatment of ONFH.

Comparison of results of core decompression and intertrochanteric osteotomy for nontraumatic osteonecrosis of the femoral head using Cox regression and survivorship analysis.

Different surgical procedures have been recommended for osteonecrosis of the femoral head to prevent or delay the need for arthroplasty. Core decompression is a commonly used treatment in the early stages of the disease, but the published efficacy has varied markedly. Only a few comparisons of different techniques have been reported. The aim of this study was to evaluate and compare the results of 2 commonly used procedures, core decompression and intertrochanteric osteotomy, using Cox regression and survivorship analysis. A total of 177 cases with a mean age of 41 years at surgery were treated for osteonecrosis (94 core decompressions, 83 osteotomies). Any further surgery was defined as failure and endpoint. Significant risk factors for treatment failure were age > 40 years at surgery (P = .022), corticosteroid intake (P < .001), advanced stage of necrosis (Steinberg stage > or =III, P=.04), and core decompression (P = .084). To analyze the influence of the surgical procedure, patients with corticosteroid treatment were excluded, and survival analysis was performed. This analysis revealed survival rates of 74% after osteotomy and 78% after core decompression 6 years postoperatively in early, precollapse stages (P = .819). In advanced stages, the rate of survival for hips after core decompression was lower (56%) than in hips after osteotomy (76%) (P = .056). Our results indicate that core decompression may be as effective as intertrochanteric osteotomy in precollapse stages but is less traumatizing and is cost-effective. For postcollapse hips, intertrochanteric osteotomy should be considered.

[The importance to generate robot-assisted milled cavities for total hip replacement. A comparative experimental study: manual versus robotic preparation]. / Die Bedeutung der Fräsbahngenerierung für die roboterassistierte Implantation von Hüftendoprothesenschäften. Vergleichende experimentelle Studie: Hand- vs. Roboterpräparation.

We present an experimental study to determine the effectiveness of computer assisted robotic bone preparation with regard to primary rotational stability in comparison to hand broaching. 5 different cementless stems were standardized implanted in synthetic femora and measured in a specially designed apparatus (displacement in 6 degrees of freedom). In addition the contact areas of the stems and the bone were visualized. The S-ROM- and ABG-stems were more stable in hand broached femora. The Osteolock-, G2- and Vision-2000-stems were more stable in the robot group. The mode of fixation of each implant could be characterized in relation to its position and its stiffness (primary rotational stability). The contact areas differed in some prosthesis in the way of preparation. The findings highlight the current difficulties in creating a perfect match of robotically milled cavity and stem geometry to achieve enhanced stability.

Dependency of cement mantle thickness on femoral stem design and centralizer.

Deficient cement mantles may be detrimental with regard to long-term outcome of cemented femoral stems. We performed a cadaver study on 48 left femora with 4 different stem designs (1 anatomic, 3 straight) to study the influence of stem design, centralizer, and femur type on cement mantle thickness. A radiographic and microradiograhic analysis was done. Overall, 88% of stems were aligned within 1 degrees of neutral in the frontal plane. In Gruen zones 1 through 7, we measured 24 thin cement mantles (<2 mm) in 19 specimens with no correlation to stem design or zone. In the sagittal plane, typical areas of thin cement mantles were identified in Gruen zones 8 and 9 (n = 39) and 12 (n = 21). The anatomic stem design carried the lowest risk (54%) of producing a thin cement mantle proximally in Gruen zones 8 and 9. The risk for straight stem designs was >90%. Straight stems without centralizer showed the highest risk of thin cement mantles in Gruen zone 12 (93%). Centralizers were efficient to prevent thin cement mantles in zone 12 but had no effect proximally. Lateral radiographs are essential to allow for adequate radiographic assessment of the cement mantle and stem alignment. There is a high risk of producing thin cement mantles in Gruen zones 8 and 9, in particular when straight stems are used. Posterior canal entry and low neck osteotomies are essential. Anatomic stems respect the anatomy, allow for more even cement mantles, minimize the risk of thin cement mantles without the use of centralizers, and may be considered in the femur with marked proximal bow.

Cement penetration in the proximal femur does not depend on broach surface finish.

In a cadaver study, we prepared 29 paired human cadaver femora using 3 different broaches of identical geometry but different surface characteristics. In one group of 20 pairs, preparation with chipped-toothed broaches was compared to diamond-shaped broaches; in the other group of 9 pairs, polished tamps for compaction of cancellous bone were compared with chipped-tooth broaches. Cancellous bone was irrigated with 1 liter pulsed lavage. The specimens were embedded in specially-designed pots. Palacos R and Simplex bone cements were used. After vacuum mixing, the cement was applied in a retrograde manner and subjected to a standard pressure protocol with a constant force of 3,000 N. Radiographs were taken and horizontal sections were obtained at predefined levels using a diamond saw. Microradiographs were taken, digitized and analyzed to assess cement penetration into cancellous bone. In 6 of 9 femora prepared using smooth tamps, femoral fractures occurred despite careful preparation technique. The microradiographic evaluation showed no significant morphometric differences between diamond and chipped-tooth or between polished and chipped-tooth broaches with regard to cement penetration into cancellous bone. Therefore, in the presence of pulsed lavage, one finds no significant effect of broach surface characteristics on cement penetration into cancellous bone of the proximal end of the femur.

[Significance of jet lavage for in vitro and in vivo cement penetration]. / Die Bedeutung der Jet-Lavage für das In-vitro- und In-vivo-Zementierergebnis.

AIM: The purpose of this study was to determine the efficacy of pulsatile jet lavage and manual syringe lavage with regard to their cleansing capabilities as measured by cement penetration into cancellous bone both in vivo and in vitro. METHODS: Three separate experiments were performed. Study A: In a cadaver study 36 left human cadaver femora were used for implantation of cemented femoral components. Conventional broaches were used for femoral preparation. Bone lavage was carried out either using jet lavage or manual syringe lavage of equal volume. The allocation to two different lavage groups was randomised. In both groups high-pressurising cementing techniques were implemented with the use of a proximal seal and additional finger packing. Study B: To guarantee standardised cement pressurisation and equal bone quality, the influence of jet lavage (1000 ml) versus syringe lavage (1000 ml) was studied in 11 paired human cadaver femora in an additional study without prosthesis implantation. The specimens were imbedded in specially designed pots. Bone cement was applied in a retrograde manner and subjected to a standard pressure protocol with a constant force of 3000 N. Study C: To directly compare the effectiveness of both pulsatile jet and syringe lavage with regard to cement penetration in vivo, a new sheep model allowing for standardised bilateral, simultaneous cement pressurisation was used. After femoral neck osteotomies both femoral cavities of 10 sheep were prepared for retrograde cement application. After randomisation one side was lavaged with 250 ml irrigation using a bladder syringe, the contralateral femur with the identical volume but using a pulsatile lavage. A specially designed apparatus was used to allow for bilateral simultaneous cement pressurisation. ANALYSIS: In all studies horizontal sections were obtained from the femoral specimens at predefined levels using a diamond saw. Microradiographs were taken and analysed using image analysis to assess cement penetration into cancellous bone. RESULTS: Study A: Compared with syringe lavage the use of jet lavage significantly improved the penetration of cement into cancellous bone (p = 0.027). In the presence of strong, dense cancellous bone the findings were more pronounced. Study B: Our results show that in equal quality bone, the use of jet lavage yields significantly (p < 0.001) improved cement penetration compared to syringe lavage specimens. Study C: The results of the in vivo study confirmed the superiority of jet lavage bone surface preparation (p = 0.002). CONCLUSIONS: The use of jet lavage yields significantly improved interdigitation between cancellous bone and cement both in vitro and in vivo and should be regarded as mandatory in cemented total hip arthroplasty. High pressurising techniques are effective means to improve cement penetration, but should only be administered with jet lavage to reduce the risk of fat embolism.

Loss of collagen type IV in rheumatoid synovia and cytokine effect on the collagen type-IV gene expression in fibroblast-like synoviocytes from rheumatoid arthritis.

Collagen type IV is a structural matrix protein which contributes to the structural organization of the synovia. In order to characterize the distribution of this protein in synovia with chronic synovitis, collagen type IV was detected by immunochemistry in normal synovia and in synovia from patients with osteoarthritis (OA) and rheumatoid arthritis (RA). A decrease of collagen type IV was observed in synovial layers of rheumatoid synovia, which statistically correlated with the grade of inflammation and with the thickness of the synovial layer. In vitro, we found no differences in the gene expression of collagen type IV in cultures of fibroblast-like synoviocytes (FLS) derived from OA and RA using a reverse-transcriptase polymerase chain reaction. Nevertheless, we observed a downregulating effect of tumor necrosis factor-alpha and interleukin (IL)-1beta on the gene expression of collagen type IV only in FLS isolated from patients with RA. The effect of IL-1beta was dose dependent. In summary, we observed an inflammation-associated decrease of collagen type IV in the synovial layer of rheumatoid synovia. Inflammatory cytokines may play a role in regulating the synthesis of collagen type IV in the rheumatoid process in vivo.

Lavage technique in total hip arthroplasty: jet lavage produces better cement penetration than syringe lavage in the proximal femur.

Sixteen paired human cadaver femora were prepared using conventional broaches. Cancellous bone was irrigated with 1 L pulsed lavage in one femur and 1 L syringe lavage in the contralateral femur. The specimens were embedded in specially designed pots, and vacuum-mixed bone-cements were applied in a retrograde manner. After application of a standard pressure to the pots, the femora were removed and radiographed, and horizontal sections were obtained and analyzed to assess cement penetration into cancellous bone and the ratio of the area of supported to unsupported cancellous bone (Rcb). Our results show that in equal quality bone, the use of jet lavage yields significantly (P < .0001) improved cement penetration and Rcb compared with syringe lavage specimens. Jet lavage should be considered routine to achieve interdigitation with cancellous bone in cemented total hip arthroplasty.

[Cemented hip prosthesis implantation--decreasing the rate of fat embolism with pulsed pressure lavage]. / Zementierte Hüftendoprothetik--Verminderung des Fettembolierisikos mittels gepulster Druckspülung.

Intraoperative fat embolism associated with cemented total hip arthroplasty is a well recognized complication. In a new sheep model allowing for standardized bilateral, simultaneous cement pressurization we studied the effectiveness of both pulsatile and syringe lavage of equal volume with regard to their cleansing capabilities as measured by fat and bone marrow intravasation. The operative procedure involved bilateral placement of intravenous catheters into the external iliac veins via retroperitoneal approach. After femoral neck osteotomies both femoral cavities were prepared for retrograde cement application. After randomization one side was lavaged with 250 ml irrigation using a bladder syringe, the contralateral femur with the identical volume but using a pulsatile lavage. A specially designed apparatus was used to allow for bilateral simultaneous cement pressurization. Venous blood from both iliac catheters was then collected, anticoagulated and a quantitative and qualitative fat analysis was performed. Despite equal volume manual lavage produced significantly higher fat and bone marrow intravasation (P < 0.001) than pulsatile lavage thus suggesting that not only the volume but also the quality of bone lavage is an essential factor influencing the risk of fat embolism and adverse cardiorespiratory effects. Our findings further emphasize the important role of pulsatile lavage in preventing fat and bone marrow embolisation during cemented total hip arthroplasty.

[Effects of the cementing technique on cementing results concerning the coxal end of the femur]. / Einfluss der Zementiertechnik auf das Zementierergebnis am koxalen Femurende.

The purpose of this study was to determine the influence of jet-lavage and cement pressurising techniques upon cement penetration into proximal femoral cancellous bone. In a cadaver study 60 left human cadaver femora were used for implantation of cemented stem components. Four different groups of cementing techniques were generated, the allocation to the groups was randomized. Bone lavage was carried out either using jet-lavage or manual syringe lavage, cement application differed with regard to the amount of pressurisation used. Five different stem designs were used. Radiographs were taken and horizontal sections were obtained at predefined levels (2 cm) using a diamond saw. Microradiographs were taken and analysed using image analysis to assess cement penetration into cancellous bone. In an additional study the influence of jet-lavage (1000 ml) versus syringe lavage (1000 ml) was studied in 11 paired human cadaver femora. The specimens were imbedded in specially designed pots. Bone cement was applied in a retrograde manner and subjected to a standard pressure protocol with a constant force of 3000 N. The analysis protocol was identical to the main experiment. Both jet-lavage and pressurisation of bone cement significantly improved the penetration of cement into cancellous bone (p = 0.027 and p = 0.003, respectively). In the presence of strong, dense cancellous bone the findings were more pronounced. In the additional comparative study cement intrusion was significantly better (p < 0.001) in the jet-lavage group. We did not observe an influence of the stem type upon outcome (penetration). The use of jet-lavage yields significantly improved cement penetration and should be regarded mandatory in cemented total hip arthroplasty. High pressurising techniques are effective means to improve the interdigitation between cancellous bone and cement, but should only be administered in combination with jet-lavage to reduce the risk of thrombo-embolic complications.

[Effect of a rasp surface on cement penetration in paired cadaver femurs]. / Einfluss der Raspeloberfläche auf die Zementpenetration an gepaarten Leichenfemora.

AIM: The purpose of this investigation was to study two different broach surface designs with regard to cement penetration into human cancellous bone. METHODS: In a cadaver study 15 paired human cadaver femora were prepared using broaches of identical geometry but different surface characteristics. All left femora were prepared using chipped toothed broaches, all right femora using diamond shaped broaches. Cancellous bone was irrigated with 1 liter pulsed lavage. The specimens were imbedded in specially designed pots. Bone cement was applied in a retrograde manner and subjected to a standard pressure protocol with a constant force of 3000 N. Radiographs were taken and horizontal sections were obtained at predefined levels using a diamond saw. Microradiographs were taken and analyzed using image analysis to assess cement penetration into cancellous bone. RESULTS: Pressure curves recorded during cement pressurisation were comparable. The microradiographic evaluation revealed no significant morphometric differences in the different groups with regard to cement penetration into cancellous bone. These findings were similar in all sections obtained. CONCLUSIONS: A standardized model was developed allowing comparison of cement penetration into cancellous bone depending on bone preparation. In the presence of pulsed lavage there is no significant influence of broach surface characteristics on cement penetration into cancellous bone of the upper end of the femur.

[Anchoring principles in hip prosthesis implantation. II: Acetabulum components]. / Verankerungsprinzipien in der Hüftendoprothetik. Teil II: Pfannenkomponente.

In this review the different anchorage concepts of cemented and cementless acetabular components are presented and clinical long-term results--if available--are discussed. Despite numerous design improvements and modifications the long-term durability of acetabular components remains a major concern with results being clearly inferior than achieved with femoral components. Until valid, prospective long-term success is proven for cementless designs cemented acetabular fixation using modern cementing technique must be regarded as standard treatment. However, successful fixation over 15-20 years very much depends on the quality of operative and cementing technique. Some cementless systems appear easier to use and have been documented to offer reliable mid-term survival rates. In young patients cementless devices have been well established and for some systems promising 10-year results have been published.

[Anchoring principles in hip endoprostheses. I: Prosthesis stem]. / Verankerungsprinzipien in der Hüftendoprothetik. Teil I: Prothesenstiel.

Total hip replacement is one of the most successful procedures in surgery. In Germany there is a great variety of cemented and uncemented implants with different principles of fixation. We reviewed the different principles, with particular reference to long-term clinical outcome, and discuss the most popular systems available in Germany. Despite many new developments which have been made in the field of cementless hip replacement, cemented total hip arthroplasty will remain the "gold standard" until prospective long-term data (> 15 years) of cementless systems become available.

Core decompression in osteonecrosis of the femoral head: risk-factor-dependent outcome evaluation using survivorship analysis.

The results of core decompression of the femoral head in the treatment of osteonecrosis are analyzed. This study includes 94 hips in 74 patients with a follow-up time ranging between 18 months and 15 years (average 6 years). There had been no need for further surgery 2 years postoperatively in 85% of the hips with preoperative Steinberg stages 0, I and II when compared with 66% with preoperative stages III, IV and V. At 4 years postoperatively the corresponding figures are 73 compared to 55%; and 6 years postoperatively 69 compared to 49%. This difference was significant (P=0.0402). Further significant risk factors are corticosteroid administration, smoking and alcohol intake. The results of core decompression are good when the preoperative lesion is at Steinberg stage 0, I and II and the patient does not present with other risk factors. In cases with risk factors the outcome is significantly less good. The procedure is not indicated in the presence of advanced disease.

External fixation in proximal tibial osteotomy: a comparison of three methods.

During a period of 6 years (1990-1996), 154 patients with unilateral gonarthrosis underwent proximal tibial osteotomy using 3 different methods of external fixation: (1) closing wedge osteotomy and bilateral fixation; (2) closing wedge osteotomy with unilateral fixation, and (3) opening wedge osteotomy with unilateral fixation. The most common complications were pin-tract infection (25%), temporary nerve palsy (10%), and loss of alignment (17%). At least one complication developed in 33% of patients in this study, indicating that the use and technique of external fixation in proximal tibial osteotomy can be problematic.

[Status of cementation technique in total hip endoprostheses in Germany]. / Der Stand der Zementiertechnik bei Hüfttotalendoprothesen in Deutschland.

AIM: The correlation between improved cementing techniques and improved long-term results after total hip arthroplasty (THA) is well documented. The purpose of this study was to assess the use of modern cementing techniques in Germany. METHODS: A detailed questionaire regarding cement and bone preparation, cementing techniques on actabulum and femur, and implants used was sent to 584 German orthopaedic and trauma hospitals, as well as to visiting surgeons with an interest in THA. In total, 333 questionaires were available for evaluation and statistical analysis. RESULTS: In this survey, Palacos bone cement is used in 84%, low viscosity cement in 9%. Cement chilling is performed in 58%. Mixing is done by hand without vacuum mixing systems in 53%, the mixing time is standardised in 66%. For the femur 83% and for the acetabulum 74% preserve cancellous bone, 13% use pulsed lavage. Cement application is done via cement gun in 97%, in 41% in a retrograde manner and in 18% without drainage of the intramedullary canal. A cement pressurising technique is used in 63% for the femur and in 57% for the acetabulum. A cement mantle of less than 2 mm is attempted in 41%. More than 50 different stem design are implanted with the Müller straight stem being used most often, followed by anatomic designs. Almost 50% of hips are used with a 28 mm head, and almost 50% are implanted with a 32 mm head. Half the heads are ceramic, half are metal. CONCLUSIONS: The results from this survey document, that overall only slightly more than 10% of hips are implanted using second/third generation (modern) cementing techniques with application of pulsed lavage. This has implications on the number of arthroplasties that may require revision. From the data available the current status of cementing technique in Germany cannot be judged satisfactory.