A retrospective study of 32 patients with primary tumours of the cauda equina is presented. Most of the patients were initially diagnosed as having prolapsed intervertebral discs and treated accordingly. The correct diagnosis was eventually made, usually after a long delay, and confirmed by myelography. Treatment consisted of laminectomy and excision of the tumour. Only one tumour was frankly malignant; all the remaining patients were relieved of their pain and the majority recovered completely. The exceptions were those patients with long-standing neurological deficits; this highlights the importance of early diagnosis and correct treatment before irreparable damage occurs.

1. Mucopolysaccharides were analysed in the urine of thirteen patients with Morquio's syndrome aged between three and fifty-nine years and of fourteen controls of comparable ages.

2. There were no significant qualitative or quantitative differences between patients and controls.

3. The clinical and radiological findings suggested that these patients did not have the "Morquio-Ullrich" form of the disease, which appears on retrospective assessment of case reports to be more uniform and less diffuse than the Morquio-Brailsford form which may include a number of possibly unrelated diseases.

4. Keratosulphate has so far been demonstrated in the urine only of patients with the "Morquio-Ullrich" form of the disease, although the mucopolysaccharide excretion has been investigated in only a few patients with the Morquio-Brailsford form. The normal mucopolysaccharide excretion of the present series of patients suggests that a normal mucopolysaccharide excretion distinguishes the Morquio-Brailsford from the Morquio-Ullrich form, the latter having a number of features overlapping with Hurler's disease, where large amounts of mucopolysaccharide other than keratosulphate are excreted.

5. Both qualitative and quantitative analysis of urinary mucopolysaccharide are thus necessary to distinguish between Hurler's disease, the Morquio-Ullrich form and the Morquio-Brailsford's form of Morquio's syndrome.

Aims. Tenosynovial giant cell tumour (TGCT) is one of the most common soft-tissue tumours of the foot and ankle and can behave in a locally aggressive manner. Tumour control can be difficult, despite the various methods of treatment available. Since treatment guidelines are lacking, the aim of this study was to review the multidisciplinary management by presenting the largest series of TGCT of the foot and ankle to date from two specialized sarcoma centres. Methods. The Oxford Tumour Registry and the Leiden University Medical Centre Sarcoma Registry were retrospectively reviewed for patients with histologically proven foot and ankle TGCT diagnosed between January 2002 and August 2019. Results. A total of 84 patients were included. There were 39 men and 45 women with a mean age at primary treatment of 38.3 years (9 to 72). The median follow-up was 46.5 months (interquartile range (IQR) 21.3 to 82.3). Localized-type TGCT (n = 15) predominantly affected forefoot, whereas diffuse-type TGCT (Dt-TGCT) (n = 9) tended to panarticular involvement. TGCT was not included in the radiological differential diagnosis in 20% (n = 15/75). Most patients had open rather than arthroscopic surgery (76 vs 17). The highest recurrence rates were seen with Dt-TGCT (61%; n = 23/38), panarticular involvement (83%; n = 5/8), and after arthroscopy (47%; n = 8/17). Three (4%) fusions were carried out for osteochondral destruction by Dt-TGCT. There were 14 (16%) patients with Dt-TGCT who underwent systemic treatment, mostly in refractory cases (79%; n = 11). TGCT initially decreased or stabilized in 12 patients (86%), but progressed in five (36%) during follow-up; all five underwent subsequent surgery. Side effects were reported in 12 patients (86%). Conclusion. We recommend open surgical excision as the primary treatment for TGCT of the foot and ankle, particularly in patients with Dt-TGCT with extra-articular involvement. Severe osteochondral destruction may justify salvage procedures, although these are not often undertaken. Systemic treatment is indicated for unresectable or refractory cases. However, side effects are commonly experienced, and relapses may occur once treatment has ceased. Cite this article: Bone Joint J 2021;103-B(4):788–794

Objectives. Prosthetic joint infection (PJI) diagnosis is a major challenge in orthopaedics, and no reliable parameters have been established for accurate, preoperative predictions in the differential diagnosis of aseptic loosening or PJI. This study surveyed factors in synovial fluid (SF) for improving PJI diagnosis. Methods. We enrolled 48 patients (including 39 PJI and nine aseptic loosening cases) who required knee/hip revision surgery between January 2016 and December 2017. The PJI diagnosis was established according to the Musculoskeletal Infection Society (MSIS) criteria. SF was used to survey factors by protein array and enzyme-linked immunosorbent assay to compare protein expression patterns in SF among three groups (aseptic loosening and first- and second-stage surgery). We compared routine clinical test data, such as C-reactive protein level and leucocyte number, with potential biomarker data to assess the diagnostic ability for PJI within the same patient groups. Results. Cut-off values of 1473 pg/ml, 359 pg/ml, and 8.45 pg/ml were established for interleukin (IL)-16, IL-18, and cysteine-rich with EGF-like domains 2 (CRELD2), respectively. Receiver operating characteristic curve analysis showed that these factors exhibited an accuracy of 1 as predictors of PJI. These factors represent potential biomarkers for decisions associated with prosthesis reimplantation based on their ability to return to baseline values following the completion of debridement. Conclusion. IL-16, IL-18, and CRELD2 were found to be potential biomarkers for PJI diagnosis, with SF tests outperforming blood tests in accuracy. These factors could be useful for assessing successful debridement based on their ability to return to baseline values following the completion of debridement. Cite this article: M-F. Chen, C-H. Chang, L-Y. Yang, P-H. Hsieh, H-N. Shih, S. W. N. Ueng, Y. Chang. Synovial fluid interleukin-16, interleukin-18, and CRELD2 as novel biomarkers of prosthetic joint infections. Bone Joint Res 2019;8:179–188. DOI: 10.1302/2046-3758.84.BJR-2018-0291.R1

We evaluated triple-phase bone scintigraphy in the differential diagnosis of peri-prosthetic infection in 46 patients with a total hip replacement or bipolar hemiarthroplasty who were due for revision surgery. There were 18 men and 28 women, with a mean age at operation of 64.6 years (28 to 81). We defined peri-prosthetic infection as an increased uptake of radioisotope in all the phases of triple-phase bone scintigraphy and validated these results against the histological and/or microbiology results in every case. The positive and negative predictive values for the presence of infection were 83% and 93%, respectively. The diagnostic sensitivity was 88% and the specificity was 90%. This study indicates that triple-phase bone scintigraphy is a useful tool in the detection of peri-prosthetic infection and offers a cost-effective method of screening

We describe a schwannoma located in the mid-diaphyseal region of the fibula of a 14-year-old boy. Radiologically this was an expansile, lytic, globular and trabeculated lesion. MRI showed a narrow transition zone with a break in the cortex and adjacent tissue oedema. Differential diagnosis included schwannoma, fibrous dysplasia, giant cell tumour and aneurysmal bone cyst. The tumour was excised en bloc, with marginal resection limits, and there has been no recurrence two years after surgery. Histopathological examination confirmed the diagnosis of classic schwannoma. There were typical hypercellular Antoni A zones, less cellular Antoni B zones, and diffuse immunoreactivity to S100 protein. This is the first report of schwannoma involving a long bone in a child

Aims. We present a case series of ten metal-on-polyethylene total hip arthroplasties (MoP THAs) with delayed dislocation associated with unrecognised adverse local tissue reaction due to corrosion at the trunnion and pseudotumour formation. . Methods. The diagnosis was not suspected in nine of the ten patients (six female/four male; mean age 66 years), despite treatment in a specialist unit (mean time from index surgery to revision was 58 months, 36 to 84). It was identified at revision surgery and subsequently confirmed by histological examination of resected tissue. Pre-operative assessment and culture results ruled out infection. A variety of treatment strategies were used, including resection of the pseudotumour and efforts to avoid recurrent dislocation. . Results. The rate of complications was high and included three deep infections, two patients with recurrent dislocation, and one recurrent pseudotumour. . Conclusion. This series (mean follow-up of 76 months following index procedure and 19 months following revision THA) demonstrates that pseudotumour is an infrequent but important contributor to delayed instability following MoP THA. It is easy to overlook in the differential diagnosis, especially if the alignment of the components is less than optimal, leading to an assumption that malalignment is the cause of the dislocation. The instability is likely to be multifactorial and the revision surgery is complex. Take home message: Due to the high complication rate associated with revision in this cohort, the diagnosis should be borne in mind when counselling patients regarding the risks of revision surgery. . Cite this article: Bone Joint J 2016;98-B:187–93

Acute bone and joint infections in children are serious, and misdiagnosis can threaten limb and life. Most young children who present acutely with pain, limping, and/or loss of function have transient synovitis, which will resolve spontaneously within a few days. A minority will have a bone or joint infection. Clinicians are faced with a diagnostic challenge: children with transient synovitis can safely be sent home, but children with bone and joint infection require urgent treatment to avoid complications. Clinicians often respond to this challenge by using a series of rudimentary decision support tools, based on clinical, haematological, and biochemical parameters, to differentiate childhood osteoarticular infection from other diagnoses. However, these tools were developed without methodological expertise in diagnostic accuracy and do not consider the importance of imaging (ultrasound scan and MRI). There is wide variation in clinical practice with regard to the indications, choice, sequence, and timing of imaging. This variation is most likely due to the lack of evidence concerning the role of imaging in acute bone and joint infection in children. We describe the first steps of a large UK multicentre study, funded by the National Institute for Health Research, which seeks to integrate definitively the role of imaging into a decision support tool, developed with the assistance of individuals with expertise in the development of clinical prediction tools.

Cite this article: Bone Joint J 2023;105-B(3):227–229.

Aims

Low-grade central osteosarcoma (LGCOS), a rare type of osteosarcoma, often has misleading radiological and pathological features that overlap with those of other bone tumours, thereby complicating diagnosis and treatment. We aimed to analyze the clinical, radiological, and pathological features of patients with LGCOS, with a focus on diagnosis, treatment, and outcomes.

Aims

We aimed to evaluate the utility of ⁶⁸Ga-citrate positron emission tomography (PET)/CT in the differentiation of periprosthetic joint infection (PJI) and aseptic loosening (AL), and compare it with ^99mTc-methylene bisphosphonates (^99mTc-MDP) bone scan.

The differential diagnosis of the painful total hip arthroplasty (resurfacing or total hip) includes infection, failure of fixation (loosening), tendinitis, bursitis, synovitis, adverse local tissue reaction (ALTR) to cobalt-chromium alloys, and non-hip issues, such as spinal disorders, hernia, gynecologic, and other pelvic pain. Assuming that the hip is the source of pain, the first level question is prosthetic or non-prosthetic pain generator? The second level prosthetic question is septic or aseptic? The third level question (aseptic hips) is well-fixed or loose? ALTR is best diagnosed by cross-sectional imaging. Successful treatment is dependent on correct identification and elimination of the pain generator. Treatment recommendations for ALTR and taper corrosion are evolving

Idiopathic calcium pyrophosphate deposition disease (pseudogout) has a variable presentation. Many joints are usually affected; single joint disease is uncommon. We present a case report of primary monoarticular pseudogout affecting the hip. The diagnosis was made on the appearance and analysis of specimens obtained at arthroscopy. Monoarticular pseudogout is rare, but should be considered in the differential diagnosis of any presentation of joint pain

Osteochondrosis juvenilis is caused by a dysfunction of endochondral ossification. Several epiphyses and apophyses can be affected, but osteochondrosis juvenilis of the medial malleolus has not been reported. We describe a 12-year-old boy with bilateral pes planovalgus who was affected by this condition. Conservative management was successful. The presentation, aetiology and treatment are described and the importance of including it in the differential diagnosis is discussed

We report an unusual presentation of a solitary plasma-cell myeloma of the spine in an adolescent patient. Our case indicates the need to consider plasma-cell myeloma as a differential diagnosis even in younger patients

1. Five cases of bilateral glenoid hypoplasia are described. Flattening of the humeral heads and sometimes other skeletal abnormalities coexisted. 2. The condition is considered to be congenital. 3. The differential diagnosis and etiology are discussed

A case of intracortical haemangioma in the tibial diaphysis is reported. The radiological and macroscopic features were identical with osteoid osteoma. In view of this similarity, haemangiomata, despite their rarity at this site, must be considered in the differential diagnosis of osteoid osteoma

1. Three cases of hereditary sensory neuropathy are reported. 2. Neuropathic destruction of joints and chronic infected ulcers are the primary problems of management. 3. This entity must be considered in the differential diagnosis of trophic ulcerations of the extremities

Aims

Accurate diagnosis of chronic periprosthetic joint infection (PJI) presents a significant challenge for hip surgeons. Preoperative diagnosis is not always easy to establish, making the intraoperative decision-making process crucial in deciding between one- and two-stage revision total hip arthroplasty (THA). Calprotectin is a promising point-of-care novel biomarker that has displayed high accuracy in detecting PJI. We aimed to evaluate the utility of intraoperative calprotectin lateral flow immunoassay (LFI) in THA patients with suspected chronic PJI.

Aims

The aim of this study was to report the patterns of symptoms and insufficiency fractures in patients with tumour-induced osteomalacia (TIO) to allow the early diagnosis of this rare condition.

1. Five cases of calcified enchondroma are described. In all except one the condition was symptomless and was discovered accidentally. 2. The radiographic features are described and the differential diagnosis is discussed. 3. It is emphasised that when the diagnosis is in doubt biopsy should be undertaken

1. An ancillary diagnostic technique using Fluorine-l8 or Strontium-87m is described, and has assisted in the correct diagnosis of fifty-two patients admitted with the provisional diagnosis of infective spondylitis. 2. The technique is of particular value in the assessment of reactivation of chronic spinal infections and in the differential diagnosis of atypical lesions

Aims

The aim of this study was to reassess the rate of neurological, psoas-related, and abdominal complications associated with L4-L5 lateral lumbar interbody fusion (LLIF) undertaken using a standardized preoperative assessment and surgical technique.

1. A woman of seventy-four presenting with gigantism of the left hand and foot, lipomatosis, progressive arthropathy and psoriasis is described. 2. The associations of the various conditions are examined in the light of the previously reported cases and the differential diagnosis of this condition (macrodystrophia lipomatosa) from other causes of localised gigantism is discussed

1. Eight cases of congenital vertical talus in infancy are reported. The principal differential diagnosis at this age is from talipes calcaneo-valgus. 2. The deformity is primarily a dorsal dislocation of the talo-navicular joint. 3. Closed reduction can be achieved if treatment begins at birth. Open reduction is indicated for the deformity uncorrected by the age of three months

1. A case is reported which shows the typical features of osteopathia striata in all the long bones and probably in the pelvis, with the features of osteopetrosis in the skull and ribs. 2. The occurrence of longitudinal striation in osteopoikilosis and osteopetrosis is described, and the possible relationship between these two diseases and osteopathia striata is discussed. 3. The differential diagnosis is indicated

1. The clinical and radiological features of thirty-two feet with congenital vertical talus are described and subdivided into groups determined by the presence or absence of associated abnormalities. 2. The differential diagnosis of congenital vertical talus from flat foot, talipes calcaneus and uncorrected club foot is discussed. 3. No benefit came from either non-operative treatment or tenotomy of the tibialis anterior

1) A case is reported of paraplegia with normal radiographic appearances in which cervical cord damage was shown at autopsy to have been due to hyperextension injury. 2) The mechanism of such injuries is discussed, together with the differential diagnosis from acute prolapse of an intervertebral disc. 3) The grave dangers of using the fully extended position of the cervical spine in the management of these cases is noted

Aims

Psychological status may be an important predictor of outcome after periacetabular osteotomy (PAO). The aim of this study was to investigate the influence of psychological distress on postoperative health-related quality of life, joint function, self-assessed pain, and sports ability in patients undergoing PAO.

We report eight patients with prominent cystic changes in the head of the fibula. Seven of these had osteoarthritis of the adjacent knee, and five had evidence of local deposition of calcium pyrophosphate dihydrate crystals. A radiographic survey of 470 knees in 254 patients with osteoarthritis suggested that such cysts are rare, but should be considered in the differential diagnosis of such changes before expensive or invasive investigations are performed

1. Seven cases of sacral extradural cyst are reported. 2. The etiology and clinical features are discussed and the literature reviewed. 3. The differential diagnosis is discussed; certain features, useful in making the diagnosis of sacral extradural cysts, are recorded. 4. When a cyst causes symptoms excision brings relief. Because some cysts are symptomless, it is important to exclude an accompanying prolapsed intervertebral disc

1. Stress fractures of the femoral neck in twenty-five patients are described. 2. Two distinct radiological types, compression fractures and transverse fractures, are described. A clinical distinction cannot be made in the early stages. 3. The importance of the early differential diagnosis between the two types is emphasised because the transverse stress fracture of the femoral neck will become displaced. 4. The morbidity after a displaced transverse fracture of the femoral neck can be severe

We report six patients with isolated paralysis of the infraspinatus and discuss the diagnosis, pathology, treatment, and outcome over a mean follow-up period of 33 months. Four patients were shown to have space-occupying lesions at the spinoglenoid notch by MRI or ultrasonography or both, and ganglia were confirmed and removed surgically in three, with good results. Ganglia at this site are not uncommon and should be included in the differential diagnosis of patients presenting with shoulder pain and weakness

1. Four cases of ochronotic arthropathy have been studied and the related literature has been reviewed. 2. Ochronotic arthropathy is a rare condition resulting from an inborn error of metabolism occurring as a Mendelian recessive characteristic. Its incidence, however, may have been underestimated. 3. Problems of differential diagnosis are discussed and it is suggested that more widespread screening should be undertaken in order to assess the true incidence of the condition

1. Two cases of swelling in the popliteal fossa due to a local hypertrophy of the semimembranosus muscle are described and two further cases thought to be of similar nature are noted. 2. The swelling was soft, not tender, fairly well circumscribed, and without signs of inflammation. Its most characteristic feature was an increase in size and hardening of the swelling during active flexion of the knee. 3. This condition should be considered in differential diagnosis of swellings of the popliteal fossa

1. The deep posterior muscles of the neck are innervated by the posterior branches of spinal nerves, which branch off immediately after the root emerges from the intervertebral foramen. Electromyographic examination of these muscles permits a differential diagnosis to be made between intraforaminal and extraforaminal brachial plexus lesions. 2. The earlier diagnosis and prognosis thus achieved permit definitive treatment, in particular suture of the torn nerve trunks in recent extraforaminal cases

1. An account is given of a family in which five members in three generations were affected by osteochondritis involving the hips, in three cases bilaterally. 2. One patient showed aseptic osseous necrosis of the epiphyses of the ankles and fingers. 3. The differential diagnosis between Perthes' disease and multiple epiphysial dysplasia is discussed, but it is not certain into which category these patients fall. 4. The assistance of a family history and skeletal survey in diagnosis is illustrated

We have reviewed a consecutive series of six professional footballers who presented with intractable hip pain which was attributed at arthroscopy, to an anterior acetabular labral tear with adjacent chondral damage. The location and type of labral tear were identical for each patient. There was no evidence of acetabular dysplasia. A variable area of chondral damage was associated with the labral tear. All unstable tissue was resected. Five returned to professional football at the highest level. Acetabular labral pathology should be included in the differential diagnosis of footballers with hip or groin pain. Arthroscopy of the hip is an appropriate method of diagnosis and treatment and minimises the length of rehabilitation required

1. A case of low back pain due to a sacral extradural cyst is reported. Radiographs of the sacrum showed an ovoid expansion of the sacral canal. Myelography and exploratory laminectomy revealed an extradural cyst associated with a defect in the dural root sleeve surrounding the second left sacral roots. Relief of symptoms followed evacuation of the cyst and repair of the defect. 2. The differential diagnosis of the condition, the varieties of extradural cyst, and the features which distinguish them from perineurial cysts are described

1. Haemorrhage into the fascial compartment which contains the iliacus muscle and the femoral nerve is a common complication of haemophilia. 2. The iliacus haematoma syndrome is described and illustrated from the authors' study of thirty episodes occurring in twenty-four patients. 3. The anatomy of the iliopsoas fascia is described and the mechanism of femoral nerve compression explained. 4. Differential diagnosis, prognosis and treatment are discussed and the necropsy findings in one patient are presented. 5. An instance of iliacus haematoma occurring as a complication of anticoagulant therapy is recorded

1. Nineteen patients with classical rheumatoid arthritis complicated by severe subluxation of the cervical spine are reported. 2. Thirteen patients had atlanto-axial subluxation. This was the only level ofinvolvement in ten. 3. The next most frequent level to be involved was C.4-5. This occurred in five patients. 4. Eleven patients required surgery for symptoms or signs of spinal cord compression or vertebral artery insufficiency. 5. Operations included six posterior fusions, three anterior fusions and two laminectomies. 6. The differential diagnosis, the radiological findings, the indications for surgery and the results of treatment are discussed

1. Congenital vertical talus is described and the criteria for diagnosis are emphasised. The need for its distinction from other forms of convex pes valgus is stressed. 2. The operative technique of Stone for Lloyd-Roberts (1963) is detailed and the results of seven such operations are examined. 3. Departure from the technique in any respect has resulted in an unsatisfactory outcome, whereas stringent observation of the operative details has resulted in uniformly good results in four patients. 4. Certain aspects of diagnosis, differential diagnosis, etiology, pathology and surgical management are discussed, together with a review of some of the relevant literature

Pyomyositis is rarely seen in temperate climates. Typically, it presents with the formation of an abscess requiring surgical drainage and it has been reported as a differential diagnosis for septic arthritis of the hip. We describe the occurrence of pyomyositis of the iliacus muscle in a ten-year-old girl which was diagnosed by MRI and blood culture. Formation of an abscess did not occur despite marked focal inflammation and swelling of the muscle. Conservative treatment with antibiotics alone led to complete clinical and radiological resolution of the infection. We could find no previous description of pyomyositis in a child in the British orthopaedic literature. Orthopaedic surgeons, particularly those with a paediatric interest, should be aware of this condition and its presentation, diagnosis and treatment

We report eight cases of fracture of the cuboid in seven children under four years of age, collected during a two-year period. There was no history of trauma in five of the patients. This fracture is rarely diagnosed and has probably been under-reported. Small children are poor historians and difficult to examine, and early radiographs may be normal or have only subtle abnormalities. Cuboid fracture should be considered in the differential diagnosis of limping toddlers, and a bone scan may be needed to confirm the diagnosis earlier than radiography. These fractures heal completely, without sequelae. Treatment in a short-leg walking cast is recommended, primarily for reasons of comfort

With advances in the treatment of patients with chronic renal failure, their life expectancy has increased. In turn, the prevalence of osteitis fibrosa cystica, a manifestation of secondary hyperparathyroidism, and β2 microglobulin amyloidosis, a result of long-term haemodialysis, has risen. While both conditions share similar radiological features, their management is very different. We present the case of a patient with renal failure who had been receiving haemodialysis for over 20 years. Lytic lesions had been observed in the proximal part of both femurs for ten years. A presumptive diagnosis of osteitis fibrosa cystica was made. However, no regression of the lesions occurred after parathyroidectomy. The patient subsequently developed sequential pathological fractures through the lesions, for which bilateral total hip replacements were performed. Histology of the lesions revealed that the patient was in fact suffering from amyloidosis. In patients with chronic renal failure, osseous amyloidosis is a highly probable differential diagnosis, especially if no regression of a lytic lesion is observed after parathyroidectomy

We report four patients with a form of Ehlers-Danlos syndrome associated with soft-tissue contractures from birth and skin hyperalgesia. In early infancy, these cases were thought to be forms of arthrogryposis multiplex congenita, Larsen's syndrome or Marfan's syndrome. The characteristic triad of signs of Ehlers-Danlos disease gradually appeared from four to six years of age, allowing us to establish the correct diagnosis. We discuss the differential diagnosis of these connective-tissue disorders and the problems of the orthopaedic treatment of the associated joint deformities. Ehlers-Danlos syndrome is a heterogeneous group of metabolic diseases of collagen and our cases constitute a group which is distinct from the conventional types

The clinical and pathological features of six cases of desmoplastic fibroma of bone are presented. Desmoplastic fibroma is rarely seen as a primary tumour of bone; when it does occur the sites of predilection are the long bones, but other sites such as the scapula and os calcis can be involved. Radiographically the lesion tends to expand the bone from within; it is well-demarcated and lytic, often with a trabeculated soap-bubble appearance. The cellular structure and the morphological arrangement are similar to those of aggressive fibromatosis of soft tissues. Differential diagnosis from malignant spindle-cell lesions of bone is important because the treatment of choice for desmoplastic fibroma of bone is simply excision with a thin layer of healthy tissue

In a series of seventeen patients with unilateral osteoarthritis of the hip a scintiscanning follow-up study was made before and after total hip replacement for the assessment of the normal course of the 87mSr-scintiscan. In another series of twenty-eight patients with total hip replacement a photoscan was made as a supplement for the diagnosis of loosening of one or both components of a total hip implant. In most of these cases it proved to be a useful method, especially when clinical and raidological examination was inconclusive. It is concluded that up to six months after operation increased osteoblastic activity exists; the scintiscan became normal after that time. 87mSr scintiscanning offers a safe and simple technique for the assessment of the success and stability of total hip arthroplasty. It is also a useful aid for the early detection of loosening and infection. The procedure can help in the differential diagnosis of complaints after total hip replacement