Lower limb reconstruction in tumor patients using modular silver-coated megaprostheses with regard to perimegaprosthetic joint infection: a case series, including 100 patients and review of the literature.

PURPOSE AND OBJECTIVE: Bone resection regarding adequate surgical margins is the treatment of choice for malignant bone tumors. In the case of metastasis-related complications, so-called skeletal-related events, it is highly important to achieve pain relief and a stable joint situation to re-mobilize the patients immediately following surgery. To bridge the often large osseous defect zones after tumor resection, both cemented and uncemented modular endoprosthetic systems are widely used. Patients undergoing tumor-related endoprosthetic orthopedic surgery are facing high risk for developing a periprosthetic joint infection (PJI). The immunocompromised condition due to anti-neoplastic treatment and long operation time with large exposure of tissue contributes to a high risk of infection. METHODS: The authors present a case series of 100 patients (31% primary bone tumor and 69% metastasis-related surgery) undergoing tumor-related lower limb salvage surgery with special regard to periprosthetic joint infection and the management of this "difficult to treat" situation. Furthermore, a review of the current literature regarding infection following bone tumor resection and endoprosthetic reconstruction is performed and discussed. RESULTS: The median follow-up was 24 months (range 12-108 months). Ten patients (10%) suffered from a periprosthetic joint infection. We recorded six acute infections (type I) <4 weeks after surgery, one infection >4 weeks after surgery (type II), and three late infections (type III). According to the definition of Laffer et al., three of our patients (30%) are probably free of infection, one patient died of PJI-associated sepsis, and five patients were free of infection, but without restoration of the affected joint. CONCLUSION: In conclusion, our own results show that perimegaprosthetic joint infection among silver-coated implants, in patients undergoing tumor-related surgery of the lower limb, is lower compared to non-silver-coated implants. Due to heterogeneity of patients and potential treatment options, the treatment regime should be tailored for the patients' individual situation.

Perioperative management and outcome of fracture treatment in patients with haemophilia without inhibitors.

INTRODUCTION: Fractures in persons with haemophilia (PWH) are not uncommon and require an interdisciplinary approach to maintain haemostasis during surgical treatment. AIM: The aim of this study was to evaluate the perioperative management and outcome in PWH following fracture fixation compared to a matched non-haemophilic control group. METHODS: A cohort of 44 PWH who underwent 46 surgical fracture fixations was retrospectively compared to 46 non-haemophilic patients (matched-pair controls). Patients were classified according to the fracture localization: (i) proximal upper extremity (PrUEx; n = 7), (ii) distal upper extremity (DiUEx; n = 12), (iii) proximal lower extremity (PrLEx; n = 13) and (iv) distal lower extremity (DiLEx; n = 14). Both groups were assessed for length of hospital stay, duration of surgery, drainage use and complication rates. RESULTS: There was no significant difference regarding the duration of the preoperative hospital stay between PWH and controls. Only PWH who were operated at the DiUEx stayed significantly longer in hospital (4.8 ± 3.7 days) than controls (2.2 ± 2.3 days; P = 0.039). Operation time was significantly longer in PWH with fractures treated at the DiLEx (64.9 ± 26.6 min) compared to the controls (49.8 ± 37.9 min; P = 0.035). Neither frequency nor duration of surgical drainage placement differed significantly between the two groups. The overall complication rate in both groups was low without a statistically significant difference. CONCLUSION: An optimal interdisciplinary perioperative management provided the surgical treatment of fractures in PWH can be performed safely with a low complication rate.

Musculoskeletal pain: a new algorithm for differential diagnosis of a cardinal symptom in pediatrics.

Musculoskeletal pain (MSP) is a common childhood complaint associated with multiple differential diagnoses, including cancer. Considering the expanding spectrum of diagnostics, evaluat-ing a young patient with MSP is a challenge today, particularly for non-specialists in a primary care setting. Since childhood cancer is rare and most cardinal symptoms mimic rather non-serious diseases, misdiagnosis is not uncommon, but of significant prognostic relevance. To build the appropriate bridge between primary and secon-dary care for a child presenting with MSP, thereby preventing treatment delay and longterm sequelae, initial evaluation should follow a comprehensive, multidisciplinary, systematic and stepwise approach, which unites the patient's individual anamnestic, psychosocial, and clinical charac-teristics. After a systematic review of the literature, we generated multidisciplinarily quality-assured recommendations for efficient, rational and cost-effective primary care assessment of pediatric MSP. The algorithm promotes the identification and structured interpretation of the patient's individual clinical clues. It should serve the primary care physician to recognize when further intervention, rather than reassurance and follow-up, is needed using the minimum amount of testing to make an appropriate, prompt diagnosis in the clinical situation "child presenting with MSP". A German version of this algorithm has been published in the Guideline-Portal of The Association of the Scientific Medical Societies ("Arbeitsgemeinschaft der Wissenschaftlichen Medizinischen Fachgesellschaften", AWMF) in November 2013.

[Comparison of treatment results of idiopathic and non-idiopathic congenital clubfoot : prospective evaluation of the Ponseti therapy]. / Vergleich der Behandlungsergebnisse bei kongenitalen idiopathischen und nichtidiopathischen Klumpfüßen : Prospektive Evaluation der Ponseti-Therapie.

BACKGROUND: Clubfoot deformity is one of the most common congenital musculoskeletal deformities and occurs in newborns with different neuromuscular diseases. To date the Ponseti method is the gold standard for the treatment of idiopathic clubfeet but not for non-idiopathic clubfeet which are associated with neuromuscular diseases. The results of the treatment for congenital idiopathic and non-idiopathic clubfeet according to Ponseti performed in our department since 2004 were compared concerning results and relapse surgery with particular reference to the compliance of the parents concerning the use of an abduction splint. PATIENTS AND METHODS: A total of 101 children (28 female and 73 male) with 159 clubfeet were treated with the Ponseti method and included in this prospective non-randomized cohort study. Of these children 27 with 48 affected feet suffered from neuromuscular diseases which are associated with clubfoot deformity, such as myelomeningocele (n=4), arthrogryposis (n=9) and various other syndromes (n=14). The degree of the deformity was evaluated with the Pirani score initially, after casting and at follow-up. Parents were asked at follow-up to state subjectively how compliant they were with the abduction splint treatment. The necessity of surgical treatment of relapses was recorded. Statistical analysis was performed applying χ(2) and Kruskal-Wallis tests for the comparison of idiopathic and non-idiopathic clubfeet. RESULTS: The average period of follow-up was 36 month (range 6-75 months) and non-idiopathic clubfeet were initially significantly more severely deformed according to the Pirani-score (p=0.013). Treatment of non-idiopathic clubfeet was started significantly later than that of idiopathic clubfeet (p=0.003) and took significantly longer (p <0.001). A correlation between the initiation of casting and the duration of casting was not found (p=0.399). At the end of the casting period no significant differences were found between correction of idiopathic and non-idiopathic clubfeet with respect to the Pirani score (p=0.8). The mean score after casting was 0.1 in both groups. At mid-term follow-up the score increased in both groups but stayed below 0.5 with non-idiopathic clubfeet showing a significantly higher score than idiopathic clubfeet (p=0.014). Relapse surgery was necessary in 11% of the patients. No significant difference in the revision rate was found between the two groups (p=0.331) and peritalar release was not necessary in either group. The rate of revisions correlated with the compliance concerning the use of the abduction splint (p <0.001). Only 61% of the parents stated that they adhered strictly to the abduction splint treatment recommendations with no significant difference between the groups (p=0.398). CONCLUSION: This study shows good initial results after Ponseti treatment for idiopathic as well as non-idiopathic clubfeet. Based on the good functional results all clubfeet should initially be treated with the Ponseti method regardless of the etiology.

[Reduction of unstable and dislocated hips applying the Tübingen hip flexion splint?]. / Die Tübinger Hüftbeugeschiene als Repositionsorthese?

BACKGROUND: The indication for the use of the Tübingen hip flexion splint is a dysplastic hip without instability. According to current knowledge dysplastic unstable or dislocated hips should be treated with a stable retention device such as a modified Fettweis cast. The aim of this study was to evaluate the treatment effect of the Tübingen hip flexion splint when applied to dysplastic unstable hips (type IIc unstable according to the classification of Graf) and dislocated hips (types D, III and IV according to the classification of Graf) within the first week of life. PATIENTS AND METHODS: All newborns with an unstable hip type IIc or worse detected by ultrasound in the first week of life were treated with a Tübingen hip flexion splint. A prospective cohort trial was performed between November 2007 and December 2010. The initial hip type according to the ultrasound classification of Graf, the start and the duration of treatment with the Tübingen hip flexion splint as well as the rate of success were evaluated. Due to the small number of patients non-parametric tests were used for statistical analysis. RESULTS: A total of 50 dysplastic unstable or dislocated hips in 42 newborns were treated with the Tübingen hip flexion splint. The distribution of pathological hip types was 6 type IIc unstable, 33 type D, 10 type III and 1 type IV. Therapy was started on average on day 3.5 (range 1-8 days) of life and 49 out of 50 hips were successfully treated with the Tübingen hip flexion splint. Solely the type IV hip could not be reduced in the Tübingen hip flexion splint. Thus 98% of the dysplastic unstable or dislocated hips were successfully converted into type I hips with an α-angle of more than 64° in the splint. The mean time for achieving an α-angle ≥ 64° was 51.6 ± 18.9 days (range 21-87 days). No statistically significant relationship was found between the duration of therapy and the time when treatment was started, early or late within the first week of life (p = 0.152). Furthermore, no correlation was detected between the duration of therapy and the initial hip type determined by ultrasound (p = 0.886). In all successfully treated cases therapy could be discontinued during the exponential part of Tschauner's maturation curve of hip development. CONCLUSION: When recognized within the first week of life dysplastic unstable hips (type IIc unstable according to the classification of Graf) and dislocated hips with a cranially dislocated cartilage roof (types D and III according to the classification of Graf) can be successfully treated with the Tübingen hip flexion splint provided that the parents show good compliance concerning the treatment regimen.

[Modified percutaneous achillotentomy according to Hoke for minimally invasive treatment of pointed foot]. / Modifizierte perkutane Achillotenotomie nach Hoke zur minimal-invasiven Spitzfußbehandlung.

OBJECTIVE: Various underlying diseases can lead to a pointed foot in children and adults. If the gastrocnemius and soleus muscles are structurally shortened, various surgical procedures are available to correct this malposition. A preferred method for restoring a normal dorsiflexion of the upper ankle joint is percutaneous achillotentomy according to Hoke. Consideration of the physiological-anatomical torsion of the Achilles tendon as it corresponds to the White technique and is recommended by some authors shows in our experience no advantages. In the present work, we show a modified, likewise minimally invasive form of this surgical method with which immediate full weight-bearing of the affected lower extremity is possible from postoperative day 1. INDICATIONS: All clinically relevant structural pointed foot, for primary and/or for revision treatment. CONTRAINDICATIONS: Infection in the area of the operation. SURGICAL TECHNIQUE: No tourniquet, 3 incisions with the 15 mm knife: (1) medial distal at the transition from the Achilles tendon to the calcaneus, (2) medial proximal approximately 7 cm proximal to the 1st stab incision, (3) lateral, midway between the first two incisions; no skin suturing, application of a lower leg cast. POSTOPERATIVE MANAGEMENT: On postoperative day 1, cast hybridization using Scotchcast (3M Deutschland GmbH, Neuss, Germany), followed by pain-adapted full weight-bearing; removal of the cast in the outpatient department after 4 weeks. RESULTS: A total of 104 patients underwent surgery, 1 case of a local pressure point, no infections, no overcorrections, no Achilles tendon ruptures, in one case a postoperative relapse due to a broken cast. The risk of overcorrection to the foot, which was considered the main complication in the literature, did not occur in any of the cases.

[Botulinum toxin A in children with infantile cerebral palsy: indications and treatment concepts]. / Botulinumtoxin A bei Kindern mit infantiler Zerebralparese: Indikationen und Anwendungskonzepte.

Botulinum toxin A treatment in children with cerebral palsy is now well established as a safe and effective therapy option. However, a standardised injection strategy is still lacking. There is no doubt concerning the necessity for long-term therapy to cover the duration of motor development as well as for adequate prevention of fixed contractures. The appropriate dose and treatment concept to be used, however, is still controversial. The modern BoNT-A treatment concept must combine safety and efficacy with the availability of this treatment option throughout the duration of growth in these children. Consequently, in order to provide the best possible support for motor development at each individual motor milestone and using moderate dose recommendations, the "Key-Muscle Concept" has been developed.

Erratum to: Modified neck-lengthening osteotomy after Morscher in children and adolescents.

Erratum to:Oper Orthop Traumatol 2018 https://doi.org/10.1007/s00064-018-0561-9 The article was wrongly published under the article type "Review". Please note that the article is an "Original Paper".The publisher apologizes to authors and readers.

[Modified neck-lengthening osteotomy after Morscher in children and adolescents]. / Modifizierte Schenkelhalsverlängerungsosteotomie nach Morscher bei Kindern und Jugendlichen.

OBJECTIVE: Growth disorders (e. g. caused by congenital hip dislocation, Perthes disease or bacterial coxitis) often lead to an infantile deformity of the proximal femur with a shortened femoral neck and displaced grater trochanter. In 1988, Morscher and Buess described a femoral neck lenghtening osteotomy for treatment of adults. For the first time, we show a modification of this osteotomy for children and adolescents with a locking plate system. The aim is to restore the normal anatomy of the femoral neck and biomechanics of the proximal femur. INDICATIONS: All symptomatic deformities of the proximal femur with a shortened femoral neck and a proximal displacement of the greater trochanter. CONTRAINDICATIONS: Bacterial coxitis within the last two years; elevated infections parameters. Acetabular dysplasia with a lack of femoral head containment. SURGICAL TECHNIQUE: Two osteotomies: one at the level of the greater trochanter to transfer it. The second osteotomy at the level of the distal femoral neck. Stabilization with a locking plate system (LCP Pediatric Hip Plate 130°, Synthes, Oberdorf, Switzerland). POSTOPERATIVE MANAGEMENT: Full weight bearing to a body weight of 55 kg; partial weight bearing with a body weight >55 kg for 6 weeks. RESULTS: No intraoperative or postoperative complications were observed in 5 female patients (mean age 11.67 years). After a follow-up of 6-12 weeks, none of the patients presented a Trendelenburg's sign. After 3-6 months, full range of motion was possible.

Temporary epiphysiodesis using the FlexTack™ implant (tension band) featuring a modified explantation technique.

OBJECTIVE: Presenting the implantation of the PediatrOS™ FlexTack™ (Merete, Berlin, Germany) for growth guidance and a modified explantation procedure to facilitate explantation and prevent bone and soft tissue damage. INDICATIONS: Implantation: Genua vara and valga, coxa vara, varus and valgus deviation of the ankle joint, the elbow joint and the wrist Modified Explantation: Removal of the implant after successful limb correction or dislocation of the implant. CONTRAINDICATIONS: Implantation: Closed growth plates, insufficient remaining growth potential, acute or chronic infection, insufficient osseous structures, severe muscular, nervous or vessel diseases endangering the respective limb Explantation: General inoperability of the patient. SURGICAL TECHNIQUE: Implantation: Localization of the growth plate. Insertion of K­wire parallel to joint line on the joint side. Setting of the implant. Insertion of second K­wire and insertion with the implantation instrument and hammer. Modified Explantation: Cutting of the implant bridging part. Both ends of the bridging part are bent vertically to prevent soft tissue damage. Dissection of both implant arms from the bone with the chisel. Extraction in 360° motion using tooth extraction pliers. POSTOPERATIVE MANAGEMENT: Implantation: Full weight bearing. X­ray controls every 3 months to control growth correction. Explantation: Full weight bearing. RESULTS: Complications such as breaking of the k­wires, breaking of the chisel or extraction of adhering bone tissue occurred in 14 of the 64 (21.9%) explanted FlexTack implants. Complication-free removal using the original instruments provided by the manufacturer was possible for five implants. The modified explantation procedure as described above was applied in 45 explanted implants (70.3%) with complete removal of the implant without further complications within the follow up period.

[Ponseti method for treatment of idiopathic clubfoot]. / Klumpfußtherapie nach Ponseti.

OBJECTIVE: Pain-free, plantigrade, functional foot through gentle manipulation without extended surgery and with decreased probability of relapse. INDICATIONS: Idiopathic clubfoot; neurogenic and secondary clubfeet. CONTRAINDICATIONS: None. SURGICAL TECHNIQUE: Simultaneous correction of all components of the clubfoot. Mainly conservative, with serial casts. Slight supination to address the cavus and increasing abduction to align the midfoot bones while putting counter-pressure on the head of the talus. Surgery primarily only to correct the equinus, which can often not be accomplished through casting, and consists of a simple subcutaneous section. Due to tendency to relapse, further surgery might be necessary, followed by serial casting. Remaining deformity can be treated by percutaneous lengthening of the Achilles tendon, percutaneous release of the plantar fascia or a transfer of the tibialis anterior tendon to the third cuneiform. POSTOPERATIVE MANAGEMENT: Abduction orthosis for stabilization of the clinical result 24 h/day for 3 months, then only at night- and naptime through end of the third year of life. Follow-up every 3-4 months.

[Botulinum Toxin in the Musculoskeletal System]. / Botulinumtoxin am Bewegungsapparat.

Over the last 20 years, botulinum toxin has proven to be an effective agent in the orthopaedic treatment of musculoskeletal diseases. The author presents a detailed summary of the data on the use of botulinum toxin in different indications. New indications and dosages will be developed in the coming years. As some of the newer indications for botulinum toxin are off-label, its pharmacokinetics must be carefully considered and the indication must be strictly based on current study data. Physicians using this drug should attend special professional courses.

[Modified PemberSal osteotomy technique with lyophilized human allograft]. / Technik der modifizierten PemberSal-Osteotomie mit lyophilisiertem humanem Allograft.

OBJECTIVE: PemberSal osteotomy to improve femoral head coverage by rotating the acetabular roof ventrally and laterally. INDICATIONS: Insufficient coverage of the femoral head, and can be combined with other surgical procedures such as femoral intertrochanteric varus-derotation osteotomy and open reduction for developmental dysplasia and dislocation of the hip or to improve sphericity and containment in Legg-Calvé-Perthes disease. This specific acetabuloplasty can only be performed in patients with an open epiphyseal growth-plate. CONTRAINDICATIONS: Increased bleeding tendency (e.g., inherited or iatrogenic); elevated anesthetic risk such as in cerebral palsy, arthrogryposis multiplex congenital, trisomies; syndromes require explicit interdisciplinary clarification to reduce perioperative risks; infections as in other elective surgeries; diseases/deformities making postoperative spica casting impossible or impractical (e.g., deformities of spinal cord or urogenital system, hernias requiring treatment); closed epiphyseal plate requires complex three-dimensional corrections of the acetabular roof (e.g., triple/periacetabular osteotomy). SURGICAL TECHNIQUE: Osteotomy from the iliac bone to the posterior ilioischial arm of the epiphyseal growth-plate cartilage; controlled fracture of the cancellous bone without breaking the medial cortex of the iliac bone for ventrocaudal rotation of the acetabular roof. To refill and stabilize the osteotomy site, an allogenic bone-wedge is interponated and secured by a resorbable screw or kirschner wire. This method also allows more complex reconstructions of the acetabular roof, e.g., by including the pseudo-cup in a modified Rejholec technique. POSTOPERATIVE MANAGEMENT: A spica cast is applied to immobilize the hip for 6 weeks. Afterwards physiotherapy can be performed under weight-bearing as tolerated. Radiographic check-ups every 6 months.

[Does coxitis fugax predispose for later Perthes' disease?--first results of an insurance data-based study]. / Prädisponiert die Coxitis fugax für einen späteren Morbus Perthes?--Erste Ergebnisse einer auf Versicherungsdaten basierenden Untersuchung.

INTRODUCTION: For decades, it has been a matter of debate whether coxitis fugax (CF) may trigger the onset of Perthes' disease (PD). However, the low incidence of both conditions limits the validity of clinical studies. As a novel approach, an analysis of patient data provided by a private health insurance (PHI) was performed. After calculation of the frequencies of CF and PD possible correlations were statistically assessed. We hypothesised that CF predisposes to the development of PD. MATERIALS: A retrospective database analysis was conducted based on insurance data of patients aged between 1 and 14 years covering an observation period of 7 years. Cases of CF and PD were detected by a search algorithm based on the International Classification System of Diseases (ICD) encoding the ICD codes M12.85 to CF and M91.1 to PD, respectively. Cases where CF was followed by PD were separately assessed for plausibility considering the clinical course and the length of the symptom-free interval. Statistical analysis was performed by using the chi-square test with a significance level set at 5 %. RESULTS: Among a cohort of 407,875 children 960 cases of CF were detected. Of these, 876 (91.3 %) had one single event of CF whereas 84 (8.7 %) children had two or more episodes. The average incidence of CF was 0.24 % per year. The frequency of PD was calculated to be 15.7 cases per 100, 000 children per year. In eleven cases (all male) CF was found to be followed by PD, however, after checking for plausibility only three cases remained. Statistical analysis revealed that the incidence of PD in male children with a previous CF episode was 21-times higher compared to children without CF (p < 0.0001). DISCUSSION: The results of the hitherto largest study including more than 400 ,000 children showed a significantly higher rate of PD in male children with previous CF compared to boys without CF. However, different patterns of age distribution and the observation that multiple CF episodes do not trigger the development of PD contradict the assumption of a possible correlation between these two diseases. In two of the three cases where CF was followed by PD a so-called "late onset PD" was evident suggesting a misdiagnosed PD at initial presentation. The chosen study design using patient data provided by a PHI allows the acquisition and evaluation of large numbers of cases which may help to elucidate possible correlations between different medical conditions. To unambiguously answer the hypothesis of this study, the inclusion of additional insurance data is necessary.

[Impact of Preoperative Knee Stiffness on the Postoperative Outcome after Total Knee Arthroplasty in Patients with Haemophilia]. / Einfluss der präoperativen Kniesteife auf das postoperative Ergebnis nach Knieendoprothetik bei Patienten mit Hämophilie.

INTRODUCTION: Total knee arthroplasty (TKA) is an effective treatment option for patients with end-stage haemophilic arthropathy of the knee. However, the procedure is technically challenging, as knee motion is often restricted before the operation and complication rates are then thought to be higher than for patients with a normal range of motion (ROM). There is very limited information on the outcome of TKA in haemophilic patients presenting with stiff knees. The objective of the present study was to retrospectively analyse and compare the clinical results after TKA in haemophiliacs with stiff and non-stiff knees. PATIENTS AND METHODS: The results of 50 TKA procedures in 41 haemophilic patients were retrospectively evaluated at a mean follow-up of 7.2 ± 4.9 years (range 2-25 years). 20 patients presenting with 23 stiff knees - defined by a preoperative ROM of 50° or less - were compared with 21 patients with 27 non-stiff knees. Knee motion (ROM, flexion, extension), Knee Society Score (KSS/KSS function), pain status (visual analogue scale, VAS), number of bleedings and patient satisfaction were evaluated. RESULTS: The complication rate was 12 %, including two haematomas, one aseptic loosening, and three periprosthetic infections. The overall mean ROM increased from 58.6 ± 34.2° (range 0-120°) preoperatively to 85.9 ± 23.4 (35-130°) postoperatively (p < 0.005). Mean KSS and KSS function improved from 30.6 ± 11.0 points (range 10-49) and 43.4 ± 9.3 points (range 15-65) to 79.3 ± 9.6 points (range 49-95) and 68.9 ± 11.0 points (45-90), respectively (p < 0.005). The mean VAS score decreased significantly from 7.9 ± 0.8 points (range 6-9) to 1.8 ± 1.1 points (range 0-4; p < 0.005). In comparison to the non-stiff group, patients with stiff knees showed a significantly greater mean improvement in ROM (46.3 ± 21.8° [range - 10-85°] vs. 9.4 ± 16.9° [range - 30-35°]), flexion (32.8 ± 19.6° [range - 10-85°] vs. 5.2 ± 16.2° [range - 40-35°]), and flexion contracture (13.5 ± 9.6° [range 5-30°] vs. 5.9 ± 6.7° [range 5-20°]). Both KSS and KSS function were significantly inferior in stiff knees than with non-stiff knees. Nine patients with knee stiffness who underwent additional v-y quadricepsplasty to lengthen the extensor mechanism developed a mean extensor lag of 7-0° ± 4-8° (range 5-15°). At final follow-up, 37/41 patients were satisfied or very satisfied with the surgical result. CONCLUSION: TKA in haemophilic patients presenting with haemophilic arthropathy of the knee results in significant improvements in function and reduced pain. Although the ultimate clinical outcome in stiff knees is inferior to that with non-stiff knees, joint replacement surgery can be successfully performed in patients with restricted preoperative range of motion. Vy-quadricepsplasty for to facilitate exposure is associated with the development of a postoperative extensor lag and should therefore be performed restrictively. Patient satisfaction after TKA was equally high in the two groups.

Primary subacute epiphyseal and metaepiphyseal osteomyelitis in children. diagnosis and treatment guided by MRI.

We present three children with primary subacute epiphyseal and metaepiphyseal osteomyelitis. The diagnosis was delayed because of subtle radiological findings and mild general symptoms. Primary epiphyseal osteomyelitis is extremely rare. We believe that this is the first time that the MRI findings have been presented. In the first case they revealed a perforation into the knee and therefore an intra-articular epiphyseal approach was used for debridement. In the second and third cases the metaepiphyseal lesions showed considerable physical involvement and a metaphyseal approach was chosen. We believe that in this condition MRI is essential both for diagnosis and in the planning of surgical treatment.

Investigations on the functional role of angiotensin converting enzyme (ACE) in human seminal plasma.

The investigations were carried out with partially purified angiotensin converting enzyme (E.C.3.4.15.1) from human seminal plasma and from human blood plasma. The Km-constants for angiotensin converting enzyme (ACE) from both sources, estimated by the use of synthetic substrates, were in the same order. The catalytic properties of the enzymes were characterized by a series of known peptidase inhibitors. The male antifertility drug gossypol (1,1',6,6',7,7'-hexahydroxy-3,3'-dimethyl-5,5'-bis-isopropyl-(2,2' -naphthalene)--8,8'-dicarboxaldehyde) was identified as a potent ACE-inhibitor. The inhibitory constants of several kinins and other biologically active peptides were determined. Any regulatory influence of the peptides investigated on the ACE-activity in vivo is not probably. The inhibitor of Zn-containing metalloproteases 2-(N-hydroxycarboxamido)-4-methylpentanoyl-L-alanylglycin e amide) (Zinkov) selectively inhibited ACE from blood plasma, whereas ACE from seminal plasma was not influenced. In seminal plasma the majority of the enzyme is associated with macromolecular structures, identified as membrane vesicles. These vesicles contain also other enzymatic activities usually detectable in seminal plasma. In the male genital tract ACE is synthesized in the prostate, epididymis and testis. As our data indicate ACE seems not to be involved in the regulation of sperm motility.

[Evaluation of hydroxyapatite-coated Schanz screws in the Heidelberg external fixation system (HEFS)]. / Evaluation hydroxylapatitbeschichteter Schanz-Schrauben bei Verwendung des Heidelberg External Fixation System (HEFS).

The use of monolateral external fixation systems for the correction of limb length and/or axial anomalies involves the implantation of Schanz screws in the long bones for periods of weeks or months. The loosening rate, which increases with duration of implantation, is a problem. In animal experiments/superior fixation and a reduced infection rate have been reported for hydroxyapatite-coated screws in comparison with conventional screws. We report on the clinical application of 59 hydroxyapatite-coated Schanz screws in 15 external fixation mountings. The performance of the screws was evaluated by clinical and radiological criteria. Infection was seen in 15 screws, necessitating the early removal of 6 of them. In patients with a second fixation system/the infection rate was lower, with infection developing in only 1 of 12 screws.

[Tensile strength of bone fixation of hydroxyapatite coated Schanz screws of the Heidelberg External Fixation System (HEFS)--comparative torque measurements in clinical use and in cadaver tibia]. / Zur knöchernen Verankerungsfestigkeit hydroxylapatitbeschichteter Schanz-Schrauben des Heidelberg External Fixation Systems (HEFS)--Vergleichende Drehmomentmessungen im klinischen Einsatz und an der Leichentibia.

It is claimed in the literature that hydroxyapatite(HA)-coated screws of external fixators have superior fixation strength in bone, which is postulated to lead to a substantial decrease in loosening and infection rates. We report on a study of the maximum torque values developed while inserting and removing 30 HA-coated Schanz screws of 8 Heidelberg external fixation systems applied to the tibia to correct leg length differences and axial deformities. The infection rate was determined in accordance with defined criteria, and was found to be about 20% for the HA-coated screws. Screws without infection showed an extraction torque above insertion torque, screws with infection an extraction torque below. A significant correlation (p = 0.05) was seen between infection and decrease in fixation strength (quotient: loosening torque/tightening torque). To exclude the impact of such biological processes as osteointegration and bone remodelling, the clinical results were compared with the torques measured for coated and uncoated Schanz screws in a human cadaveric tibia. A significantly higher fixation strength in bone was found for HA-coated screws in comparison with uncoated screws (p = 0.002). These data warrant a clinical study directly comparing HA-coated and uncoated Schanz screws.

[Effect of various cylinder diameters of implants for lumbar inter-corporeal spinal fusion on compressive strength on the FSU model]. / Der Einfluss unterschiedlicher Zylinderdurchmesser von Implantaten zur lumbalen interkorporellen Wirbelsäulenfusion auf die Kompressionsfestigkeit im FSU-Modell.

Anterior lumbar interbody fusion (ALIF) has evolved as a minimally invasive technique for treating lumbar instability caused by degenerative lumbar disc disease. A practical surgical method is the lateral retroperitoneal approach in which cylindrical implants are inserted in the intervertebral space. The optimal diameter of these implants remains unclear. The purpose of this biomechanical study was to investigate the influence of implant diameter on selected mechanical properties of the functional spinal units (FSU). In fresh frozen bovine FSU the bone density was first determined and cylindrical implants were then inserted. The FSU were then tested under compression loading in a material-testing machine. A tendency of the "failure loads" to decrease with increasing cylinder diameter was observed. The study reveals a strong correlation between bone density and loading capacity, with higher loads being sustained by the more strongly mineralized bone. In contrast to homogeneous material, in an FSU, larger cylinder diameter does not result in an increase in compression strength.