Platelet transfusion practice and related transfusion reactions in a large teaching hospital.

BACKGROUND: Platelet transfusion practice varies widely since many aspects of platelet concentrate (PC) use have not been definitively determined. The objectives of this retrospective study were to present platelet transfusion practice and evaluate PC and patient characteristics, as well as their association with transfusion reaction (TR) rate. MATERIAL AND METHODS: Platelet transfusions over a 5-year period were analysed regarding PC characteristics (the ABO and RhD compatibility, product type, and storage duration), patient characteristics (most responsible diagnosis, age, and gender), and TR type. RESULTS: A total of 46,351 PCs were transfused: 76.4% whole blood-derived (WBD) and 23.6% single donor apheresis (SDA). Three thousand seven hundred seventy-six patients received platelet transfusions: 24.7% paediatric and 75.3% adult patients, 79.6% outpatients and 20.4% inpatients. As much as 63.1% of all transfused PCs were fresh (stored for≤3 days), 98.0% ABO-identical, and 87.3% of all PCs given to RhD- patients were RhD-. PCs were mainly transfused to haemato-oncology (76.8%) and cardiovascular surgery patients (6.5%). Overall, 84 (0.18%) TRs were reported, with allergic TRs (ATRs) being the most common. Although PC ABO compatibility and storage duration, as well as patient age and gender, showed differences in TR rate, only the use of PCs in platelet additive solution (PAS) showed a statistically significant reduction of TRs (P<0.001). CONCLUSION: Transfusion practice at the University Hospital Centre Zagreb resulted in almost all patients receiving ABO and RhD identical PCs, and most of them were fresh PCs. The most important factor affecting the incidence of TRs was platelet storage solution. The use of PAS effectively reduced the rate of TRs, particularly allergic TRs.

First Metatarsophalangeal Joint Arthroscopy of 36 Consecutive Cases.

PURPOSE OF THE STUDY In this study, we retrospectively reviewed a consecutive case series of first metatarsophalangeal (MTP) joint arthroscopies performed in our department over a span of six years. This study aimed to evaluate the efficacy and safety of arthroscopic treatment for various first MTP joint pathologies. MATERIAL AND METHODS A total of 36 patients that underwent first MTP joint arthroscopy between January 2014 and December 2019 were reviewed. The mean age at the time of surgery was 38.3 years (range, 14-65), with no gender predominance (19 males). All arthroscopies were performed by a single surgeon using a 2.7 mm arthroscope with a 30° viewing angle as well as other standard instruments with a diameter equal to or smaller than 3.5 mm. Postoperative results were assessed by a satisfaction questionnaire obtained during the telephone interview. For patients with sesamoid bone pathology ability to return to sports activities was also evaluated. RESULTS The far most common indication, in even twenty-nine patients, was hallux rigidus, five patients were treated for nonunion of sesamoid bone fracture, one patient had an osteochondral defect of the first metatarsal head and one was treated due to the development of arthrofibrosis following the open corrective procedure of hallux valgus. The mean follow-up was 31.2 months. Thirty-four patients responded to the satisfaction questionnaire. Thirty patients (88.2%) were either satisfied or very satisfied with the procedure and thirty-one (91.2%) of them stated that they would undergo the same procedure again. The satisfaction rate for patients with early stages of hallux rigidus (grade 1 and 2) was 90.4%. Only one patient in this group (2.8%) required open revision surgery due to recurrence of pain and joint stiffness. All patients with nonunion of sesamoid bone fracture were very satisfied with the procedure, and three out of four patients (75%) who were also competitive athletes resumed their sports activity at the same or improved level after the arthroscopy. Regarding arthroscopy-related complications we observed four cases (11.1%) of iatrogenic injury to dorsal sensory nerves of the great toe, resulting in only one permanent sensory impairment. DISCUSSION Considering the high satisfaction rate and low rate of complications in our study, as well as those published in the literature, we can suggest that arthroscopy of the first MTP joint is a safe and effective procedure. CONCLUSIONS Arthroscopy of the first MTP joint certainly has a place in the treatment of some pathological conditions of the first MTP joint, and in our opinion, it should be first-line surgical therapy for the initial stages of hallux rigidus and sesamoid bone pathology. Key words: arthroscopy, metatarsophalangeal joint, great toe, hallux rigidus, cheilectomy, sesamoid bone, sesamoidectomy.

Utilisation patterns of group O red blood cell transfusion by ABO and D non-identical recipients in large academic hospital.

OBJECTIVES: Several studies have raised concerns that transfusion of O red blood cells (RBCs) to ABO and D non-identical recipients can intensify group O inventory shortages. The aim of this study was to retrospectively analyse particular clinical indications and polices responsible for O RBCs use by ABO and D non-identical recipients, as well as to assess the impact of this practice on the overall utilisation of O RBCs. MATERIAL AND METHODS: Data of all transfused RBCs from 2014 to 2018 were extracted from the comprehensive database of transfusion service. Extracted variables included date of transfusion, ABO and D group of the transfused RBCs and recipients, recipient's demographic, and specific characteristics regarding transfusion requirements. RESULTS: Over a 5-year period, 124,220 RBCs were transfused: 38,962 (31.4%) group O D+ and 9109 (7.3%) group O D-. ABO and D non-identical recipient received 4842 (10.1%) of all administered O RBCs: 2880 (7.4%) of all transfused O D+ and 1962 (21.5%) of all transfused O D- RBCs. The common indications for this practice were: ABO and D mismatched hematopoietic stem cell transplantation (HSCT) (52.5%), infants under the age of 4 months (18.6%), shortage of ABO identical RBCs (9.0%), phenotype-matched RBCs (8,1%), and urgent transfusion (7.2%). CONCLUSIONS: A significant proportion of O RBCs was transfused to ABO and D non-identical recipients, mainly due to transfusion of ABO and D mismatched HSCT recipients. However, the proportion of all transfused RBCs O D+ and especially O D- remained relatively low.

Distribution of indications and procedures within the framework of centers participating in the WAA apheresis registry.

The WAA apheresis registry was established in 2003 and an increasing number of centers have since then included their experience and data of their procedures. The registry now contains data of more than 74,000 apheresis procedures in more than 10,000 patients. This report shows that the indications for apheresis procedures are changing towards more oncological diagnoses and stem cell collections from patients and donors and less therapeutic apheresis procedures. In centers that continue to register, the total extent of apheresis procedures and patients treated have expanded during the latest years.

[RARE LOCALIZATION OF OSTEOID OSTEOMA--DISTAL PHALANX OF THE RING FINGER].

With this clinical observation we would like to bring to mind osteoid osteoma as a possible cause of problems of distal phalanx of the fingers. Osteoid osteoma occurs rarely at this location and has atypical presentation. The main symptoms are swelling and redness of the fingertip with nail deformity, while typical night pain may not be present. Unusual clinical and x-ray presentation of tumor in this localization can make diagnosis of osteoid osteoma very difficult. A 20-year-old patient reported pain in the fingertip of his right ring finger persisting for five years. Swelling and redness of the fingertip combined with nail deformity was also present. X-rays showed osteolysis in the base of distal phalanx. Magnetic resonance imaging showed suspicion of osteoid osteoma, which was confirmed by computed tomography (CT). We performed surgical removal of osteoid osteoma in February 2014. The tumor was approached by longitudinal incision on the lateral side of the distal phalanx of the ring finger and the basal part of distal phalanx was cut with a small chisel to enable access to cystic change of the bone. Tumor removal with excochleation was performed and the material thus obtained was sent for histopathologic analysis. After surgery, the ring finger was immobilized in a plaster splint for a three-week period. After removal of immobilization, the patient was referred to physical therapy consisting of individual exercises in order to obtain the full range of motion in all joints of the hands and strengthen hand and forearm muscles. After surgical removal of osteoid osteoma, all symptoms disappeared completely. Histopathologic findings confirmed the diagnosis of osteoid osteoma. After physical therapy, he returned to daily activities without any problems. On regular follow ups at 3, 6 and 12 months after surgery, clinical findings were normal and the patient had no pain or discomforts. Full recovery was shown by the result of the DASH questionnaire three months after the procedure. Preoperative DASH score 54.4 decreased to 0. Distal phalanx of the finger is a very rare localization of osteoid osteoma, and typical night pain may not be present. In addition, appearance on x-rays is not typical. Instead of central enlightenment surrounded with sclerosis, x-rays usually show a lytic lesion. For this reason, it may be difficult to make the diagnosis of osteoid osteoma. The main symptom is permanent pain, swelling and redness of the finger, with nail deformity. The imaging method of choice is CT, which must be performed with thin layers of 1 to 2 mm. Furthermore, cooperation of surgeon and radiologist is extremely important to reach the accurate diagnosis. Many treatment options are described in the literature, such as CT-guided percutaneous thermocoagulation, destruction of lesions with alcohol, or CT-guided radiofrequency ablation. However, due to the proximity of neurovascular structures, tendons and joints, the best method for treatment osteoid osteoma in distal phalanx of the fingers is surgical excision or excochleation. Our conclusion is that one should always bear in mind that osteoid osteoma can be the cause of swelling of distal phalanx of the finger with nail deformity, and pain that alleviated with the use of non-steroidal anti-infl ammatory drugs. Surgical excision or excochleation is the best method for the treatment osteoid osteoma of distal phalanx of the finger.

Patellar tendinopathy: histopathological examination and follow-up of surgical treatment.

PURPOSE OF THE STUDY: The aim of this study was to determine the exact localization of the histopathological process (bone, bone-tendon junction or tendon), and to determine whether the underlying pathologic process is predominantly of inflammatory or degenerative nature, then to evaluate the outcome of the surgical treatment of patellar tendinopathy. MATERIALS: A prospective cohort study was performed in order to analyze the outcome of surgical treatment of patellar tendinopathy, as well as to document histopathological changes in bone, bone-tendon junction, and in the patellar ligament in 34 professional athletes treated with patellar apicotomy. All the patients included in the study were classified as stage 3 according to Blazina and showed no improvement after at least 6 months of conservative treatment. The postoperative follow-up was from 1 to 8 years with a mean value of 4.7 years. METHODS: The postoperative results were analyzed using a semiquantitative scoring system where the functional outcome was classified as very good if the athlete returned to his sporting activity without any negative side effects, good if the athlete resumed his sporting activities with modest painful sensations present only at the maximum level of physical exertion, and poor if any reduction of athletic activity was present. In twenty patients a histopathological examination of resected bone and tendon tissue was performed. The specimens were stained with hematoxylin-eosin and examined under a light microscope using polarization. Special stains used were Alcian blue, to detect any increase in ground substance, and Prussian blue which enhances conspicuity of hyaline degeneration and enables detection of hemosiderin. Immunohistochemistry was performed in order to analyze presence of blood vessels, leukocytes and histiocytes. RESULTS: Very good results were achieved in 20 of operated knees, good results were achieved in 12 of knees and poor results were achieved in 2 of operated knees. Pathological changes in the bone were found in 35% of analyzed specimens, abnormality at the bone-tendon junction were found in 75% of the specimens, and changes in the patellar tendon were found in all extracted specimens. The histopatholological nature of the lesions found within the tendon tissue in all of the analyzed specimens belongs to the group of degenerative changes. DISCUSSION: Currently a consenus has been established that the expression tendinitis is "out", and the term tendinopathy should be used instead. No inflammatory cells and no increase in prostaglandins can be detected in the tendons. Histopathological studies of the tissue fibrils affected by tendinosis characteristically demonstrate hypercellularity, hypervascularity, lack of inflammatory infiltrates, and disorganization and loosening of collagen fibers. CONCLUSION: The clinical results and histopathological examination in our series justified our operative method. In the chronic stage these lesions are irreversible and constitute permanent intratendinous lesions. It thus seems logical to excise these lesions from their origin at the apex of the patella and entry into the adjacent tendon. It is also recommended on the basis of our and other authors' research that the term patellar tendinopathy should be used instead of tendonitis/tendinitis.

Toxicity related to autologous peripheral blood haematopoietic progenitor cell infusion is associated with number of granulocytes in graft, gender and diagnosis of multiple myeloma.

BACKGROUND AND OBJECTIVES: We prospectively evaluated the infusion-related toxicity of autologous peripheral blood progenitor cells (PBPC) in 215 patients with haematologic malignancies or solid tumours. MATERIALS AND METHODS: PBPCs were collected by apheresis after mobilization with chemotherapy and/or granulocyte-colony-stimulating factor (G-CSF). The grafts were cryopreserved in 10% dimethyl sulfoxide (DMSO) and stored in liquid nitrogen. Patients were monitored for vital signs and symptoms of the toxicity during and after infusion. RESULTS: The adverse reactions were reported during 149 (56.9%) infusions. During 21.0% infusions occurred just one symptom classified as grade 1, while during 35.9% occurred multiple symptoms classified as grade 2. Logistic regression analysis showed that female gender, diagnosis of multiple myeloma and number of granulocytes infused per kg body weight were significant predictors of occurrence of adverse reactions during infusion. CONCLUSION: Our results indicate that beside the infused DMSO dose, the composition of graft as well as patient's diagnosis are also very important factors for infusion-related toxicity.

Stress fractures of the femoral shaft in athletes: a new treatment algorithm.

BACKGROUND: Femoral shaft stress fractures in athletes are not common but pose a great diagnostic challenge to clinicians. Because of few clinical signs, diagnosis and treatment are often delayed. Furthermore, if not treated correctly, these fractures are well known for complications and difficulties. OBJECTIVE: To develop a well structured and reproducible treatment algorithm for athletes with femoral shaft stress fractures. METHODS: The proposed algorithm is carried out in four phases, each lasting three weeks, and the move to the next phase is based on the result of the tests carried out at the end of the previous phase. Over nine years, we treated seven top level athletes, aged 17-21. In all athletes, diagnosis was based on physical examination, plain radiographs, and bone scan. RESULTS: As a result of the treatment method, all the athletes were fully engaged in athletic activity 12-18 weeks after the beginning of treatment. After completion of the treatment, the athletes were followed up for 48-96 months. During the follow up, there was no recurrence of discomfort or pain, and all the athletes eventually returned to competition level. CONCLUSION: These results and data available from the literature suggest that the algorithm is the optimal treatment protocol for femoral shaft stress fractures in athletes, avoiding the common complications and difficulties.

Multiple stress fractures in a young female runner.

The effect of exercise on female's bone metabolism has received much attention in recent years. We report on unusual case of a female runner with low body mass and amenorrhea, who suffered 4 stress fractures. Three of the stress fractures occurred during her sports career, and the fourth occurred 7 years after the cessation of sports activities. It seems that exercise-induced amenorrhea together with food restriction in the young age may cause long-term consequences on bone metabolism.

Localized pigmented villonodular synovitis of the knee: diagnostic challenge and arthroscopic treatment: a report of three cases.

The localized form of pigmented villonodular synovitis (LPVS) is a lesion characterized by focal involvement of the synovial membrane. The knee is the most commonly affected joint. We report three cases of LPVS of the knee which were not diagnosed upon clinical evaluation. The aim is to bring the attention of clinicians to this pathological entity, which is often regarded as extremely rare and is therefore not considered in the early differential diagnosis of various knee derangements. Diagnostic and therapeutic arthroscopy was performed. The lesions were completely resected and patohistological findings confirmed the diagnosis of LPVS. All of our three patients have remained asymptomatic at 8, 10, and 12-month follow-ups.

[The female athlete triad]. / Trijas sportasica.

This review offers some basic information on a syndrome described in 1992 as the female athlete triad. The increasing participation of women in competitive sports has led to significant accumulation of knowledge about potential pathological conditions due to strenuous exercise. Participation in sports that emphasize specific body image, psychological constitution of young female athletes and significantly lower daily calory intake cause the development of disordered eating, especially anorexia nervosa. Anorexia in combination with intensive training induces menstrual disorders, exercise-associated amenorrhea being the most important one. Low serum estrogen concentrations, as well as insufficient daily calcium intake have negative influence on bone mineral density, and the athletes have greater risk of developing osteoporosis and stress fractures. We described the diagnostic and therapeutic procedures necessary to detect and treat this syndrome. Education of physicians, female athletes and their coaches, as well as the screening during the annual examination, remain the most important measures of prevention.

[Overuse injury syndromes of the knee]. / Sindromi prenaprezanja u podrucju koljena.

Overuse injuries are frequent in the knee joint. The reason for this is that the knee joint is engaged in all sports activities. Furthermore, the joint area has numerous attachment points for muscles and tendons and numerous bursae. Another reason is that the specific joint between the patella and femur (patellofemoral joint) constitutes a part of the knee joint. Speaking in general terms, all overuse injuries in the knee joint can be divided in four groups according to the aspect: anterior aspect--patellofemoral pain syndrome, patellar tendinitis (jumper's knee), Osgood-Schlatter disease, Sinding Larson Johanson disease, stress fracture of the patella, fat pad syndrome; medial aspect--plica syndrome, semimembranosus tendinitis, pes anserinus tendinitis (bursitis), breaststroker's knee, medial retinaculitis; lateral aspect--Iliotibial band friction syndrome (runner's knee), Popliteal Tendinitis, Bicipital tendinitis; posterior aspect--fabellitis, medial gastrocnemius strain. There are numerous possible reasons for pain caused by overuse injuries around the knee joint, but two are the most frequent: patellar tendinitis (jumper's knee) and Iliotibial band friction syndrome (runner's knee). This paper gives a brief overview of overuse injuries of the knee joint including their definition, anatomy, aetiology, clinical symptoms and signs, and non-operative and surgical treatment.

[Anterior knee pain associated with sports and work]. / Prednja koljenska bol u sportu i radu.

Anterior knee pain is not a disease, but a syndrome with numerous causes. This paper describes its appearance in the patellofemoral joint in sportsmen and in untrained people. Chondromalacia patellae is a condition of the cartilage, not a disease, that is, it is never diagnosed alone. Relative muscular insufficiency, especially of the knee extensors, may occur in children and adolescents, as they grow rapidly. The consequence is a unbalance of active stabilizers and the disturbance of the slippery trail of patella, particularly in the presence of dysplasia of patellofemoral joint. The impingement syndrome pain occurs in sportsmen and people overloading the patellofemoral joint. Other causes of anterior knee pain should be excluded in clinical examination and slippery trail of patella, its position, and signs of instability should be determined. This paper gives an overview of patellar chondromalacia, lateral pressure syndrome, patellar subluxation, patellar acute and recurrent luxation, and idiopathic anterior knee pain. The treatment is basically conservative. Stretching exercises and the strengthening of certain groups of femoral muscles serves to regain the balance, thus normalising the slippery trail and taking off the burden from the patellofemoral joint. If conservative treatment fails, surgery is the alternative.

[Stress fractures]. / Prijelomi zamora.

Stress fractures are common overuse injuries, ranging between 1.1% and 3.7% of all athletic injuries. Causes are many and usually involve repetitive submaximal stress. There is a wide research evidence showing that training errors cause stress fractures in as many as 22% to 75% of cases. Intrinsic factors such as hormonal imbalance may also contribute to the onset of stress fractures, especially in women. During medical examination, it is essential always to bear in mind the possibility of stress fracture. Clinical diagnosis is therefore the basic procedure, followed by other diagnostic methods in the following order: radiology, scintigraphy, and MRI. Most stress fractures are uncomplicated and can be managed through rest and restriction from precipitating activities for 4-6 weeks. A subset of stress fractures can present a high risk for progression to complete fracture, delayed union, or nonunion. Specific sites for this type of stress fracture are the femoral neck, the anterior cortex of the tibia, the tarsal navicular, the fifth metatarsal (Jones fracture), and the great toe sesamoids. Therefore, high-risk stress fractures require aggressive treatment, and in some cases even surgical intervention is appropriate.

[Physical procedures in the treatment of overuse injury syndromes of the locomotor system]. / Fizikalne procedure u lijecenju sindroma prenaprezanja sustava za kretanje.

As a rule, the treatment of the overuse syndrome in the locomotor's system is non-surgical, and surgical treatment is needed on rare occasions. Non-surgical treatment should start as soon as possible. The first step is to half or modify sports activities. The treatment includes administration of non-steroidal anti-inflammatory drugs, physical therapy, stretching exercises, and the strengthening of affected muscles. The programme should be adapted to the patient, taking into account the localization and the degree of the injury, as well as his/her sport or work-related activities. The RICE therapeutic programme is important in the treatment of overuse syndromes, especially within the first 72 hours from the occurrence of first symptoms, as it shortens the duration of convalescence for as much as 50%-70%. Beside stabilisation of the joint with optimal loading of antagonistic muscles, stretching exercises have the leading position in prevention and treatment of overuse injuries. During rehabilitation, it is necessary to change activity, its duration and intensity. When a person successfully resumes its sports activities with full load, the rehabilitation is considered completed. No surgical or non-surgical method can warrant a hundred percent recovery for any localization of overuse injury. Prevention, education, and close co-operation between the physician, athlete, and the coach is therefore crucial and is receiving increasing attention.

Stress fracture of the sixth rib in an elite athlete.

We report on a previously unreported site of rib stress fracture in an elite athlete. A 27 year old sweep rower, a National champion and an Olympic finalist, presented with a 3-day history of the left-side thoracic pain. Technetium 99m bone scintigraphy showed increased focal uptake of the radioisotope, leading to the diagnosis of stress injury of the anterolateral part of the sixth rib. The probable mechanism of this injury was that strong muscle force itself was great enough to produce a fracture. In the case of our rower, the precipitation cause was only a slight change in the rowing technique, in contrast to all other reports on such rib fractures among rowers where the primary cause was an increase in the level of strength training. The treatment included a complete rest of the affected area and upper extremities, while the cardiovascular and strength fitness was maintained. The athlete was able to resume with his standard training routine less than four weeks after the onset of the symptoms.

[Conservative treatment of stress fractures of the tarsal navicular in athletes]. / Traitement conservateur des fractures de contrainte du scaphoïde tarsien chez le sportif.

PURPOSE OF THE STUDY: The purpose of the study was to propose an algorhythm for nonoperative treatment of partial tarsal navicular stress fractures in athletes, based on the results of the authors prospective research, conducted in 17 athletes. MATERIALS AND METHODS: The series included 17 patients with 18 partial tarsal navicular stress fractures (9 women and 8 men), average age 20.1 years. Patients were 10 track and field athletes mainly sprinters, 3 basketball players, two handball players, one soccer player and one volleyball player. After undergoing detailed physical examination which included x-ray examination, all patients also underwent bone scanning, and some kind of tomographic imaging (CT, MR) was done in all patients. Since all patients suffered from partial tarsal navicular stress fracture (fracture spreaded saggitally to maximal dorsal half of the bone) nonoperative treatment was conducted. Immobilization in a non weight bearing short-leg cast for a period of 6-8 weeks was followed by rehabilitation treatment consisting of 4 consecutive stages, each lasting 2 weeks. Control examination after each stage determined if patients could proceed to the following stage or if they should remain in the same stage for another two weeks. RESULTS: Patients were followed up from one to five years (average 33.9 months) and proposed algorhythm of nonoperative treatment resulted in all, except two athletes, returning to their previous level of competition activity. The average time period between initiation of treatment and resumption of full sports activity was 24 weeks (range 17 to 32 weeks). One stress fracture recurrence was encountered although all patients returned to sports activities and are constantly being monitored. DISCUSSION: No complex tarsal navicular stress fractures was found in our series. In our opinion the diminishing number of complete fractures is a consequence if quicker and more precise diagnosis. The period between the onset of symptoms and the time of correct diagnosis is becoming shorter. In our patients, this period was 3.3 months. The nonoperative treatment for tarsal navicular stress fractures was suggested with a wide variety of procedures. Based on the results if their prospective study the authors propose an algorhythm of conservative procedures in the treatment of partial tarsal navicular stress fracture. CONCLUSION: If clinical indication of tarsal navicular stress fracture is confirmed by a positive bone-scan, a CT or MRI exploration is required to distinguish stress reaction from stress fracture. In partial tarsal navicular stress fractures, immobilisation in a short-leg cast with nonweightbearing for 6 to 8 weeks depending of the magnitude of the fracture is required. This is followed by a treatment consisting of 4 two-weeks stages which clinically monitored. The previous phase can be repeated for another two weeks, depending of clinical findings. This algorhythm of nonoperative treatment of partial tarsal navicular stress fractures allowed in all athletes a return to competitive activity.

Arthroscopic retrieval of metal foreign bodies from the knee joint after war wounds.

From 1991 to 1995 metal bodies were removed from 16 knee joints (in 16 patients) using arthroscopic procedures. In 14 patients the wound resulted from explosive devices and in two from rifle bullets. Nine patients had more than one wound. Arthroscopy was performed on average 8.23 months after the injury took place (ranging from 14 days to 4 years). One metal foreign body was retrieved from 13 patients, two from two and four from one patient. The size of the metal foreign bodies varied from 2 to 24 mm, with an average of 8.61 mm. Different degrees of joint damage were present in all but one patient. The metal bodies were found in the posterolateral angle by the popliteus tendon in four patients, in three of whom the metal bodies went into this position during arthroscopy.