Pigmented villonodular synovitis of the knee: A retrospective analysis of 214 cases at a UK tertiary referral centre

AIMS

Pigmented villonodular synovitis (PVNS) is a rare, locally aggressive and potentially recurrent synovial disease. We present the largest single-centre experience of knee PVNS. Our aim was to evaluate our tertiary hospital's experience in the management of knee PVNS.

PATIENTS AND METHODS

Retrospective data collection of consecutive cases of knee PVNS from 2002 to 2015.

RESULTS

In total, 214 cases of knee PVNS were identified which represented 53.4% of all PVNS (12.1% were recurrent at presentation). 100 were localised PVNS (LPVNS), 114 diffuse PVNS (DPVNS) and two malignant PVNS. Knee PVNS was more likely to occur in females with a mean age of 39. Following surgery, 47.6% had recurrence with DPVNS as opposed to 8.6% with LPVNS. In LPVNS, there was no significant difference in recurrence between open and arthroscopic synovectomy (8.7% vs 9.1%, P>0.05). However, in DPVNS, there was a significantly higher risk of recurrence with arthroscopic compared to open synovectomy (83.3% vs 44.8%, RR=1.86 95% CI 1.32-2.62, P=0.0004).

CONCLUSION

PVNS can be difficult to treat. We found no difference in local recurrence rates between open and arthroscopic treatment of LPVNS but significantly increased rates of recurrence for DPVNS following arthroscopic treatment. We would therefore recommend open synovectomy for DPVNS.

Metal-on-polyethylene versus metal-on-metal bearing surfaces in total hip arthroplasty

The long term biological effects of wear products following total hip arthroplasty (THA) are unclear. However, the indications for THA are expanding, with increasingly younger patients undergoing the procedure.

This prospective, randomised study compared two groups of patients undergoing THA after being randomised to receive one of two different bearing surfaces: metal-on-polyethylene (MoP) n = 22 and metal-on-metal (MoM) n = 23. We investigated the relationship between three variables: bearing surface (MoP vs MoM), whole blood levels of chromium (Cr) and cobalt (Co) and chromosomal aberrations in peripheral lymphocyte pre-operatively and at one, two and five years post-surgery.

Our results demonstrated significantly higher mean cobalt and chromium (Co and Cr) blood levels in the MoM group at all follow-up points following surgery (p < 0.01), but there were no significant differences in the chromosomal aberration indices between MoM and MoP at two or five years (two years: p = 0.56, p = 0.08, p = 0.91, p = 0.51 and five years: p = 0.086, p = 0.73, p = 0.06, p = 0.34) for translocations, breaks, loss and gain of chromosomes respectively. Regression analysis showed a strong linear relationship between Cr levels and the total chromosomal aberration indices in the MoM group (R2 = 0.90016), but this was not as strong for Co (R2 = 0.68991). In the MoP group, the analysis revealed a poor relationship between Cr levels and the total chromosomal aberration indices (R2 = 0.23908) but a slightly stronger relationship for Co (R2 = 0.64292). Across both groups, Spearman’s correlation detected no overall association between Co and Cr levels and each of the studied chromosomal aberrations. There remains no clear indication which THA bearing couple is the most biocompatible, especially in young active patients. While THA continues to be very successful at alleviating pain and restoring function, the long-term biological implications of the procedure still require further scrutiny.

Cite this article: Bone Joint J 2015;97-B:1183–91.

Uncemented, custom-made, hydroxyapatite-coated collared distal femoral endoprostheses: up to 18 years' follow-up

We reviewed the outcome of 69 uncemented, custom-made, distal femoral endoprosthetic replacements performed in 69 patients between 1994 and 2006. There were 31 women and 38 men with a mean age at implantation of 16.5 years (5 to 37). All procedures were performed for primary malignant bone tumours of the distal femur. At a mean follow-up of 124.2 months (4 to 212), 53 patients were alive, with one patient lost to follow-up. All nine implants (13.0%) were revised due to aseptic loosening at a mean of 52 months (8 to 91); three implants (4.3%) were revised due to fracture of the shaft of the prosthesis and three patients (4.3%) had a peri-prosthetic fracture. Bone remodelling associated with periosteal cortical thinning adjacent to the uncemented intramedullary stem was seen in 24 patients but this did not predispose to failure. All aseptically loose implants in this series were diagnosed to be loose within the first five years. The results from this study suggest that custom-made uncemented distal femur replacements have a higher rate of aseptic loosening compared to published results for this design when used with cemented fixation. Loosening of uncemented replacements occurs early indicating that initial fixation of the implant is crucial.

Large tumoral calcinosis in the gluteal region: a case report

BACKGROUND. Tumoral calcinosis is a poorly understood phenomenon. It can be described as a syndrome of calcium deposits principally affecting the juxta-articular areas. It is a rare entity that has been poorly understood. Our aim is to highlight a special and unusual case of an 11-year-old with a large, relatively painless lump in her buttock. CLINICAL CASE. An 11-year-old girl of African descent presented to our Bone Tumour Unit after being referred by her local hospital. The girl presented with a large lump on the posterolateral aspect of the right buttock, measuring 15cm in diameter. Due to the delay in referral/diagnosis, tethering of the skin had progressed to necrosis, with a sinus discharging milky-white fluid. A MRI scan further characterised the lump as a densely calcified area within the gluteus maximus, extending to the subcutaneous tissue. The characteristic features of the calcified mass on the images led to the diagnosis of tumoral calcinosis. Laboratory test did not demonstrate any metabolic disturbances. Pathology reports further confirmed the diagnosis and the lump was successfully resected. There were no recurrences on follow-up. CONCLUSION. Several cases of tumoral calcinosis have been described in the literature; however, it remains a rare entity. Being aware of the possibility and having knowledge of tumoral calcinosis is paramount in preventing confusion and delay in diagnosis for patients and clinicians.

Custom-made rotating hinge total knee replacement in a patient with congenital tibial deficiency avoids the need for amputation

We report a unique case of a patient with type 2 congenital tibial deficiency and disabling knee osteoarthritis in whom a custom-made rotating hinge knee replacement was successfully performed, allowing continued mobilisation with a below-knee prosthesis, thereby avoiding the need for an above-knee amputation. Level of evidence Therapeutic study, Level IV.

The medium-term results of the Stanmore non-invasive extendible endoprosthesis in the treatment of paediatric bone tumours

In skeletally immature patients, resection of bone tumours and reconstruction of the lower limb often results in leg-length discrepancy. The Stanmore non-invasive extendible endoprosthesis, which uses electromagnetic induction, allows post-operative lengthening without anaesthesia. Between 2002 and 2009, 55 children with a mean age of 11.4 years (5 to 16) underwent reconstruction with this prosthesis; ten patients (18.2%) died of disseminated disease and one child underwent amputation due to infection. We reviewed 44 patients after a mean follow-up of 41.2 months (22 to 104). The mean Musculoskeletal Tumor Society score was 24.7 (8 to 30) and the Toronto Extremity Salvage score was 92.3% (55.2% to 99.0%). There was no local recurrence of tumour. Complications developed in 16 patients (29.1%) and ten (18.2%) underwent revision.

The mean length gained per patient was 38.6 mm (3.5 to 161.5), requiring a mean of 11.3 extensions (1 to 40), and ten component exchanges were performed in nine patients (16.4%) after attaining the maximum lengthening capacity of the implant. There were 11 patients (20%) who were skeletally mature at follow-up, ten of whom had equal leg lengths and nine had a full range of movement of the hip and knee.

This is the largest reported series using non-invasive extendible endoprostheses after excision of primary bone tumours in skeletally immature patients. The technique produces a good functional outcome, with prevention of limb-length discrepancy at skeletal maturity.

Custom rotating-hinge primary total knee arthroplasty in patients with skeletal dysplasia

Patients with skeletal dysplasia are prone to developing advanced osteoarthritis of the knee requiring total knee replacement (TKR) at a younger age than the general population. TKR in this unique group of patients is a technically demanding procedure owing to the deformity, flexion contracture, generalised hypotonia and ligamentous laxity. We retrospectively reviewed the outcome of 11 TKRs performed in eight patients with skeletal dysplasia at our institution using the Stanmore Modular Individualised Lower Extremity System (SMILES) custom-made rotating-hinge TKR. There were three men and five women with mean age of 57 years (41 to 79). Patients were followed clinically and radiologically for a mean of seven years (3 to 11.5). The mean Knee Society clinical and function scores improved from 24 (14 to 36) and 20 (5 to 40) pre-operatively, respectively, to 68 (28 to 80) and 50 (22 to 74), respectively, at final follow-up. Four complications were recorded, including a patellar fracture following a fall, a tibial peri-prosthetic fracture, persistent anterior knee pain, and aseptic loosening of a femoral component requiring revision. Our results demonstrate that custom primary rotating-hinge TKR in patients with skeletal dysplasia is effective at relieving pain, with a satisfactory range of movement and improved function. It compensates for bony deformity and ligament deficiency and reduces the likelihood of corrective osteotomy. Patellofemoral joint complications are frequent and functional outcome is worse than with primary TKR in the general population.

Intercalary diaphyseal endoprosthetic reconstruction for malignant tibial bone tumours

The best method of reconstruction after resection of malignant tumours of the tibial diaphysis is unknown. In the absence of any long-term studies analysing the results of intercalary endoprosthetic replacement, we present a retrospective review of 18 patients who underwent limb salvage using a tibial diaphyseal endoprosthetic replacement following excision of a malignant bone tumour. There were ten men and eight women with a mean age of 42.5 years (16 to 76). Mean follow-up was 58.5 months (20 to 141) for all patients and 69.3 months (20 to 141) for the 12 patients still alive. Cumulative patient survival was 59% (95% confidence interval (CI) 32 to 84) at five years. Implant survival was 63% (95% CI 35 to 90) at ten years. Four patients required revision to a proximal tibial replacement at a mean follow-up of 29 months (10 to 54). Complications included metastases in five patients, aseptic loosening in four, peri-prosthetic fracture in two, infection in one and local recurrence in one. The mean Musculoskeletal Tumor Society score and the mean Toronto Extremity Salvage Score were 23 (17 to 28) and 74% (53 to 91), respectively.

Although rates of complication and revision were high, custom-made tibial diaphyseal replacement following resection of malignant bone tumours enables early return to function and provides an attractive alternative to other surgical options, without apparent compromise of patient survival.

The use of massive endoprostheses for the treatment of bone metastases

Purpose. We report a series of 58 patients with metastatic bone disease treated with resection and endoprosthetic reconstruction over a five-year period at our institution. Introduction. The recent advances in adjuvant and neoadjuvant therapy in cancer treatment have resulted in improved prognosis of patients with bone metastases. Most patients who have either an actual or impending pathological fracture should have operative stabilisation or reconstruction. Endoprosthetic reconstructions are indicated in patients with extensive bone loss, failed conventional reconstructions, and selected isolated metastases. Methods and Results. We identified all patients who were diagnosed with metastatic disease to bone between 1999 and 2003. One hundred and seventy-one patients were diagnosed with bone metastases. Metastatic breast and renal cancer accounted for 84 lesions (49%). Fifty-eight patients with isolated bone metastasis to the appendicular skeleton had an endoprosthetic reconstruction. There were 28 males and 30 females. Twelve patients had an endoprosthesis in the upper extremity and 46 patients had an endoprosthesis in the lower extremity. The mean age at presentation was 62 years (24 to 88). At the time of writing, 19 patients are still alive, 34 patients have died, and 5 have been lost to follow up. Patients were followed up and evaluated using the musculoskeletal society tumour score (MSTS) and the Toronto extremity salvage score (TESS). The mean MSTS was 73% (57% to 90%) and TESS was 71% (46% to 95%). Mean follow-up was 48.2 months (range 27 to 82 months) and patients died of disease at a mean of 22 months (2 to 51 months) from surgery. Complications included 5 superficial wound infections, 1 aseptic loosening, 4 dislocations, 1 subluxation, and 1 case, where the tibial component of a prosthesis rotated requiring open repositioning. Conclusions. We conclude that endoprosthetic replacement for the treatment of isolated bone metastases is a reliable method of limb reconstruction in selected cases. It is associated with low complication and failure rates in our series, and achieves the aims of restoring function, allowing early weight bearing and alleviating pain.

Use of metal proximal radial endoprostheses for treatment of non-traumatic disorders

We have reviewed five adult patients treated with endoprosthetic reconstruction of the proximal radius following resection of non-traumatic lesions. The patients had a mean age of 33.4 years (20 to 60) at the time of surgery and the mean follow-up was 7.6 years (0.8 to 16).

Following surgery, all elbows were clinically stable and there was 100% survivorship of the prosthesis. Evaluation of function was assessed clinically and by the Mayo Elbow Performance Score, achieving a mean of 86% (70 to 100).

Results at medium-term follow-up are encouraging with regards to elbow stability, implant survivorship and functional outcome.

Custom-made hinged spacers in revision knee surgery for patients with infection, bone loss and instability

Polymethyl methacrylate spacers are commonly used during staged revision knee arthroplasty for infection. In cases with extensive bone loss and ligament instability, such spacers may not preserve limb length, joint stability and motion. We report a retrospective case series of 19 consecutive patients using a custom-made cobalt chrome hinged spacer with antibiotic-loaded cement. The "SMILES spacer" was used at first-stage revision knee arthroplasty for chronic infection associated with a significant bone loss due to failed revision total knee replacement in 11 patients (58%), tumour endoprosthesis in four patients (21%), primary knee replacement in two patients (11%) and infected metalwork following fracture or osteotomy in a further two patients (11%). Mean follow-up was 38 months (range 24-70). In 12 (63%) patients, infection was eradicated, three patients (16%) had persistent infection and four (21%) developed further infection after initially successful second-stage surgery. Above knee amputation for persistent infection was performed in two patients. In this particularly difficult to treat population, the SMILES spacer two-stage technique has demonstrated encouraging results and presents an attractive alternative to arthrodesis or amputation.

Custom-made endoprostheses for the femoral amputation stump: an alternative to hip disarticulation in tumour surgery

Disarticulation of the hip in patients with high-grade tumours in the upper thigh results in significant morbidity. In patients with no disease of the proximal soft tissue a femoral stump may be preserved, leaving a fulcrum for movement and weight-bearing. We reviewed nine patients in whom the oncological decision would normally be to disarticulate, but who were treated by implantation of an endoprosthesis in order to create a functioning femoral stump. The surgery was undertaken for chondrosarcoma in four patients, pleomorphic sarcoma in three, osteosarcoma in one and fibrous dysplasia in one. At follow-up at a mean of 80 months (34 to 132), seven patients were alive and free from disease, one had died from lung metastases and another from a myocardial infarction. The mean functional outcome assessment was 50 (musculoskeletal tumor society), 50 and 60 (physical and mental Short-form 36 scores). Implantation of an endoprosthesis into the stump in carefully selected patients allows fitting of an above-knee prosthesis and improves wellbeing and the functional outcome.

Femoral diaphyseal endoprosthetic reconstruction after segmental resection of primary bone tumours

Segmental resection of malignant bone disease in the femoral diaphysis with subsequent limb reconstruction is a major undertaking. This is a retrospective review of 23 patients who had undergone limb salvage by endoprosthetic replacement of the femoral diaphysis for a primary bone tumour between 1989 and 2005. There were 16 males and seven females, with a mean age of 41.3 years (10 to 68). The mean overall follow-up was for 97 months (3 to 240), and 120 months (42 to 240) for the living patients. The cumulative patient survival was 77% (95% confidence interval 63% to 95%) at ten years. Survival of the implant, with failure of the endoprosthesis as an endpoint, was 85% at five years and 68% (95% confidence interval 42% to 92%) at ten years. The revision rate was 22% and the overall rate of re-operation was 26%. Complications included deep infection (4%), breakage of the prosthesis (8%), periprosthetic fracture (4%), aseptic loosening (4%), local recurrence (4%) and metastases (17%). The 16 patients who retained their diaphyseal endoprosthesis had a mean Musculoskeletal Tumour Society score of 87% (67% to 93%). They were all able to comfortably perform most activities of daily living. Femoral diaphyseal endoprosthetic replacement is a viable option for reconstruction following segmental resection of malignant bone disease. It allows immediate weight-bearing, is associated with a good long-term functional outcome, has an acceptable complication and revision rate and, most importantly, does not appear to compromise patient survival.

Elastofibroma dorsi: management, outcome and review of the literature

Elastofibroma dorsi is an uncommon, benign, slow-growing soft-tissue tumour of uncertain aetiology. It classically presents as an ill-defined mass at the inferior pole of the scapula with symptoms which include swelling, discomfort, snapping, stiffness and occasionally pain. We report the symptoms, function and outcome after treatment of 21 elastofibromas in 15 patients. All were diagnosed by MRI and early in the series four also underwent CT-guided biopsy to confirm the diagnosis. In all, 18 tumours were excised and three were observed. After excision, the mean visual analogue score for pain decreased from 4.6 (0 to 10) pre-operatively to 2.4 (0 to 8) post-operatively (p = 0.04). The mean shoulder function, at a mean follow-up of 4.2 years (3 months to 16 years), was 78.1% (30 to 100) using the Stanmore percentage of normal shoulder assessment scoring system. The mean range of forward flexion improved from 135 degrees (70 degrees to 180 degrees ) to 166 degrees (100 degrees to 180 degrees ) after excision (p = 0.005). In four patients a post-operative haematoma formed; one required evacuation. Three patients developed a post-operative seroma requiring needle aspiration and one developed a superficial infection which was treated with antibiotics. Our findings support previous reports suggesting that a pre-operative tissue diagnosis is not necessary in most cases since the lesion can be confidently diagnosed by MRI, when interpreted in the light of appropriate clinical findings. Surgical excision in symptomatic patients, is helpful. It has been suggested that elastofibroma is caused by a local tissue reaction and is not a true neoplastic process. A strong association has been noted between elastofibroma and repetitive use of the shoulder, which is supported by our findings.

Total femoral endoprosthetic replacement following excision of bone tumours

We undertook a retrospective review of 33 patients who underwent total femoral endoprosthetic replacement as limb salvage following excision of a malignant bone tumour. In 22 patients this was performed as a primary procedure following total femoral resection for malignant disease. Revision to a total femoral replacement was required in 11 patients following failed segmental endoprosthetic or allograft reconstruction. There were 33 patients with primary malignant tumours, and three had metastatic lesions. The mean age of the patients was 31 years (5 to 68). The mean follow-up was 4.2 years (9 months to 16.4 years). At five years the survival of the implants was 100%, with removal as the endpoint and 56% where the endpoint was another surgical intervention. At five years the patient survival was 32%. Complications included dislocation of the hip in six patients (18%), local recurrence in three (9%), peri-prosthetic fracture in two and infection in one. One patient subsequently developed pulmonary metastases. There were no cases of aseptic loosening or amputation. Four patients required a change of bushings. The mean Musculoskeletal Tumour Society functional outcome score was 67%, the mean Harris Hip Score was 70, and the mean Oxford Knee Score was 34. Total femoral endoprosthetic replacement can provide good functional outcome without compromising patient survival, and in selected cases provides an effective alternative to amputation.

Endoprosthetic reconstruction of the distal tibia and ankle joint after resection of primary bone tumours

Endoprosthetic replacement of the distal tibia and ankle joint for a primary bone tumour is a rarely attempted and technically challenging procedure. We report the outcome of six patients treated between 1981 and 2007. There were four males and two females, with a mean age of 43.5 years (15 to 75), and a mean follow-up of 9.6 years (1 to 27). No patient developed a local recurrence or metastasis. Two of the six went on to have a below-knee amputation for persistent infection after a mean 16 months (1 to 31). The four patients who retained their endoprosthesis had a mean musculoskeletal tumour society score of 70% and a mean Toronto extremity salvage score of 71%. All were pain free and able to perform most activities of daily living in comfort. A custom-made endoprosthetic replacement of the distal tibia and ankle joint is a viable treatment option for carefully selected patients with a primary bone tumour. Patients should, however, be informed of the risk of infection and the potential need for amputation if this cannot be controlled.

The early results of joint-sparing proximal tibial replacement for primary bone tumours, using extracortical plate fixation

This paper describes the preliminary results of a proximal tibial endoprosthesis which spares the knee joint and enables retention of the natural articulation by replacing part of the tibial metaphysis and diaphysis. In eight patients who had a primary malignant bone tumour of the proximal tibia, the distal stem, which had a hydroxyapatite-coated collar to improve fixation, was cemented into the medullary canal. The proximal end had hydroxyapatite-coated extracortical plates which were secured to the remaining proximal tibial metaphysis using cortical screws. The mean age of the patients at operation was 28.9 years (8 to 43) and the mean follow-up was for 35 months (4 to 48). The mean Musculoskeletal Tumour Society score was 79% (57% to 90%), the mean Oxford Knee score was 40 points of 48 (36 to 46) and the mean knee flexion was 112° (100° to 120°). In one patient, revision to a below-knee amputation through the prosthesis was required because of recurrence of the tumour. Another patient sustained a periprosthetic fracture which healed with a painful malunion. This was revised to a further endoprosthesis which replaced the knee.

In the remaining six patients the prosthesis allowed preservation of the knee joint with good function and no early evidence of loosening. Further follow-up is required to assess the longevity of these prostheses.

Non-invasive extendible endoprostheses for limb reconstruction in skeletally-mature patients

We describe the application of a non-invasive extendible endoprosthetic replacement in skeletally-mature patients undergoing revision for failed joint replacement with resultant limb-length inequality after malignant or non-malignant disease. This prosthesis was developed for tumour surgery in skeletally-immature patients but has now been adapted for use in revision procedures to reconstruct the joint or facilitate an arthrodesis, replace bony defects and allow limb length to be restored gradually in the post-operative period.

We record the short-term results in nine patients who have had this procedure after multiple previous reconstructive operations. In six, the initial reconstruction had been performed with either allograft or endoprosthetic replacement for neoplastic disease and in three for non-neoplastic disease. The essential components of the prosthesis are a magnetic disc, a gearbox and a drive screw which allows painless lengthening of the prosthesis using the principle of electromagnetic induction. The mean age of the patients was 37 years (18 to 68) with a mean follow-up of 34 months (12 to 62). They had previously undergone a mean of six (2 to 14) open procedures on the affected limb before revision with the non-invasive extendible endoprosthesis.

The mean length gained was 56 mm (19 to 107) requiring a mean of nine (3 to 20) lengthening episodes performed in the outpatient department. There was one case of recurrent infection after revision of a previously infected implant and one fracture of the prosthesis after a fall. No amputations were performed. Planned exchange of the prosthesis was required in three patients after attainment of the maximum lengthening capacity of the implant. There was no failure of the lengthening mechanism. The Mean Musculoskeletal Tumour Society rating score was 22 of 30 available points (18 to 28).

The use of a non-invasive extendible endoprosthesis in this manner provided patients with good functional results and restoration of leg-length equality, without the need for multiple open lengthening procedures.

Outcome of intralesional curettage for low-grade chondrosarcoma of long bones

BACKGROUND

Different treatment strategies for low-grade chondrosarcomas are reported in the literature with variable outcomes. The aim of this study was to assess the oncological and functional outcomes associated with intralesional curettage and cementation of the lesion as a treatment strategy.

PATIENTS AND METHODS

We performed a retrospective review of 39 consecutive patients with intramedullary low-grade chondrosarcoma of long bones treated by intralesional curettage and cementation at our institution between 1999 and 2005.

RESULTS

There were 10 males and 29 females with a mean age of 55.5 years (32-82), and a mean follow-up of 5.1 years (3-8.7). Local recurrence occurred in two patients (5%) within the first two years following index surgery. Both were treated by re-curettage and cementation of the resultant defects. A second local recurrence developed a year later in one of these two patients, for which a further curettage followed by local liquid nitrogen treatment was performed. Overall, there were no cases of post-operative complications or metastases. The patients were assessed using the Musculoskeletal Tumour Society scoring system (MSTS) to determine limb function. The average score achieved was 94% (79-100%).

CONCLUSION

Intralesional curettage is an effective treatment strategy for low-grade intramedullary chondrosarcoma of long bones, with excellent oncological and functional results. Careful case selection with stringent clinical and radiographic follow-up is recommended.

Below-knee amputation through a joint-sparing proximal tibial replacement for recurrent tumour

We report a case which highlights the progression of osteofibrous dysplasia to adamantinoma and questions whether intralesional curettage is the appropriate treatment. The role of a joint-sparing massive endoprosthesis using cortical fixation is demonstrated and we describe a unique biomedical design which resulted in the manufacture of an end cap to allow amputation through a custom-made proximal tibial replacement, rather than an above-knee amputation following recurrence.

Potential therapeutic targets for chordoma: PI3K/AKT/TSC1/TSC2/mTOR pathway

Chordomas are radio- and chemo-resistant tumours and metastasise in as many as 40% of patients. The aim of this study was to identify potential molecular targets for the treatment of chordoma. In view of the reported association of chordoma and tuberous sclerosis complex syndrome, and the available therapeutic agents against molecules in the PI3K/AKT/TSC1/TSC2/mTOR pathway, a tissue microarray of 50 chordoma cases was analysed for expression of active molecules involved in this signalling pathway by immunohistochemistry and a selected number by western blot analysis. Chordomas were positive for p-AKT (92%), p-TSC2 (96%), p-mTOR (27%), total mTOR (75%), p-p70S6K (62%), p-RPS6 (22%), p-4E-BP1 (96%) and eIF-4E (98%). Phosphatase and tensin homologue deleted on chromosome 10 expression was lost in 16% of cases. Mutations failed to be identified in PI3KCA and RHEB1 in the 23 cases for which genomic DNA was available. Fluorescence in situ hybridisation analysis for mTOR and RPS6 loci showed that 11 of 33 and 21 of 44 tumours had loss of one copy of the respective genes, results which correlated with the loss of the relevant total proteins. Fluorescence in situ hybridisation analysis for loci containing TSC1 and TSC2 revealed that all cases analysed harboured two copies of the respective genes. On the basis of p-mTOR and or p-p70S6K expression there is evidence indicating that 65% of the chordomas studied may be responsive to mTOR inhibitors, rapamycin or its analogues, and that patients may benefit from combined therapy including drugs that inhibit AKT.

Very late local recurrence of Ewing's sarcoma--can you ever say 'cured'? A report of two cases and literature review

We report two rare cases of very late local recurrence of Ewing's sarcoma, occurring 16 years and 19 years after treatment of the primary tumour. In both cases, disease remission had been achieved. Both patients originally underwent non-surgical combined modality therapy following initial diagnosis and both were rendered disease-free. After a long latent phase, both started experiencing unexplained local symptoms. These were investigated at their local hospital but tumour recurrence was not initially considered as a cause of these symptoms. The two patients were eventually referred back to our institution after the diagnosis of recurrent Ewing's sarcoma was established. Both have successfully undergone complete excision of the recurrences and are receiving postoperative adjuvant therapy. These cases highlight the need to remain vigilant for local recurrence, however long after the initial diagnosis.

Surgical treatment of chondrosarcoma of the sternum

Purpose: We reviewed all tumours of the sternum referred to The London Bone and Soft Tissue Tumour Service between 1956 and 1997 inclusive.

Patients and results: There were eight patients with this pathology, the male to female ratio was 3:1 and their mean age was 53 years. Of these patients, three are alive and disease free, one is alive with recurrence, and four have died, two of the consequences of the disease and two of unrelated causes. Surgery is the principal treatment of these tumours both for excision and subsequent reconstruction.

Discussion: Extended disease-free survival is possible with correct diagnosis, complete excision at the first operation, appropriate skeletal reconstruction, adequate skin cover and appropriate postoperative support and follow-up.

Use of an 'internal proximal femoral replacement' with distal fixation in revision arthroplasty of the hip

We have managed 27 patients (16 women and 11 men) with a mean age of 68.4 years (50 to 84), with failed total hip replacement and severe proximal femoral bone loss by revision using a distal fix/proximal wrap prosthesis. The mean follow-up was for 55.3 months (25 to 126). The mean number of previous operations was 2.2 (1 to 4). The mean Oxford hip score decreased from 46.2 (38 to 60) to 28.5 (17 to 42) (paired t-test, p < 0.001) and the mean Harris Hip score increased from 30.4 (3 to 57.7) to 71.7 (44 to 99.7) (paired t-test, p < 0.001). There were two dislocations, and in three patients we failed to eradicate previous infection. None required revision of the femoral stem. This technique allows instant distal fixation while promoting biological integration and restoration of bone stock. In the short term, the functional outcome is encouraging and the complication rates acceptable in this difficult group of patients.

Dedifferentiated chordoma

Dedifferentiated chordoma is a rare and aggressive variant of the conventional tumour in which an area undergoes transformation to a high-grade lesion, typically fibrous histiocytoma, fibrosarcoma, and rarely, osteosarcoma or rhabdomyosarcoma. The dedifferentiated component dictates overall survival, with smaller areas of dedifferentiation carrying a more favourable prognosis. Although it is more commonly diagnosed in recurrences and following radiotherapy, there have been a few reports of spontaneous development. We describe four such cases, which were diagnosed de novo following primary excision, and discuss the associated clinical and radiological features.

A comparison of augmentation techniques for reconstruction of the extensor mechanism following proximal tibial replacement in an experimental animal model

We used an in vivo model to assess the use of an autogenous cancellous bone block and marrow graft for augmenting tendon reattachment to metallic implants. We hypothesised that augmentation of the tendon-implant interface with a bone block would enable retention of the graft on the implant surface, enhance biological integration, and result in more consistent functional outcomes compared with previously reported morcellised graft augmentation techniques.

A significant improvement in functional weight-bearing was observed between six and 12 weeks. The significant increase in ground reaction force through the operated limb between six and 12 weeks was greater than that reported previously with morcellised graft augmented reconstructions. Histological appearance and collagen fibre orientation with bone block augmentation more closely resembled that of an intact enthesis compared with the morcellised grafting technique. Bone block augmentation of tendon-implant interfaces results in more reliable functional and histological outcomes, with a return to pre-operative levels of weight-bearing by 24 weeks.

Composite ceramic bone graft substitute in the treatment of locally aggressive benign bone tumours

PURPOSE

To report the use of a composite ceramic bone graft substitute containing calcium sulphate and hydroxyapatite (HA) in the treatment of large expansive osteolytic benign bone tumours.

METHODS

4 women and 9 men aged 8 to 49 (mean, 22) years with aneurysmal bone cysts (n=6) or giant cell tumours (n=7) in the epi- or meta-physeal areas of the lower limbs underwent curettage, phenolisation, and filling with bone graft substitute containing calcium sulphate and HA. The mean tumour size was 38.5 (range, 18-65) ml. The patients were followed up for a mean of 41 (range, 33-52) months. Range of movement, Musculoskeletal Tumor Society Rating Score (MTSRS), and haematological and blood biochemical parameters were measured.

RESULTS

Two patients had recurrence at 7 and 9 months, both progressed to grade-III giant cell tumours. One underwent revision with an iliac crest autograft, whereas the other underwent en bloc excision and prosthetic replacement. The 11 other lesions displayed clinical and radiological consolidation at a mean of 4.6 (range, 3-7) months. No restriction of range of movement was observed, except in the patient undergoing prosthetic replacement. The mean MTSRS was 96% (range, 83-100%) of that expected for normal function. During the follow-up period, haematological and blood biochemical parameters stayed within normal limits.

CONCLUSION

Composite bioceramic osteoconductive grafts, which combine porous HA with calcium sulphate, provide a framework for human osteogenesis and avoid donor-site morbidity (autologous bone graft harvesting). Tumour recurrence remains a major concern especially in young patients, as revision invariably requires removal of additional bone, potentially compromising joint integrity.

Primary tumours of the synovium. A report of four cases of malignant tumour

Four patients who developed malignant synovial tumours are described; one with chondromatosis developed a synovial chondrosarcoma and three with pigmented villonodular synovitis developed malignant change. The relevant literature is discussed.

The SMILES prosthesis in salvage revision knee surgery

Revision total knee arthroplasty using a second generation modular rotating hinge design was done on thirty two knees in 30 patients over an 8-year period. Twenty-nine knees in 29 patients were followed up for 4.5-11 years (mean, 58 months). Four prostheses failed and two patients had died and one patient was lost to followup. Indications for revision were recurrent sepsis (five knees), component failure (four knees), ligamentous instability (two knees), aseptic loosening (10 knees), fracture (six knees), and gross bone loss (five knees). Early results have demonstrated improvement in both the Knee Society knee and function Scores and range of movement. The Knee Society knee score improved from 26 preoperatively to 68 postoperatively. The function score improved from 27 preoperatively to 75 postoperatively. One patient had evidence of aseptic loosening on radiographs, and the patellofemoral complication rate was low at 6%. This short-term clinical and radiographic review has demonstrated encouraging results in the use of a custom-made second generation rotating hinge component when used in revision knee surgery.

Endoprosthetic replacement of the distal humerus following resection of bone tumours

Between 1988 and 2006, 18 patients had a custom-made endoprosthetic replacement of the distal humerus for bone tumours at our institution. There were 11 primary malignant neoplasms, six secondary deposits, and one benign aggressive tumour. The mean follow-up was for 4.4 years (1 to 18.2). Complications occurred in nine patients and included aseptic loosening in three (16.6%), local recurrence in two (11%), infection in two (11%), neuropraxia of the radial nerve in one (5.5%) and a peri-prosthetic fracture in one (5.5%). Excision was inadequate in four patients (22%), all of which developed local recurrence and/or metastases. There were seven deaths from the primary disease after a mean of 2.3 years (1 to 5), one of whom had an above-elbow amputation for local recurrence seven months before death. The remaining six had satisfactory elbow function at their last follow-up. The 11 living patients were evaluated using the Musculoskeletal Tumour Society and Toronto Extremity Salvage scoring systems. The mean scores achieved were 76% (67% to 87%) and 73% (59% to 79%), respectively. Overall, 17 of 18 patients had significant improvement in the degree of their pain following operation.

Custom-made endoprosthetic reconstruction of the elbow for bone tumours is a viable treatment in carefully selected patients. It maintains satisfactory function and provides good pain relief.

Large osteoarthritic cyst presenting as soft tissue tumour - a case report

Large osteoarthritic cysts can sometimes be difficult to distinguish from primary osseous and soft tissue tumours. We present such a case involving a cyst arising from the hip joint and eroding the acetabulum which presented as a soft tissue malignancy referred to a tertiary bone and soft tissue tumour centre. We discuss the diagnostic problems it may pose, and present a literature review of the subject.

Will mesenchymal stem cells differentiate into osteoblasts on allograft?

Tissue engineering approaches for bone blocks previously have used synthetic scaffolds. Bone graft (allograft) is used to fill bone defects, but standard processing can lessen this scaffold's osteoinductive potential. We wanted to test if allografts could be used to produce a viable bone block using mesenchymal stem cells. We hypothesized that mesenchymal stem cells differentiate into osteoblasts producing extracellular matrix when cultured on allografts. We also hypothesized that the addition of osteogenic supplements would increase the rate of differentiation. To test these hypotheses, mesenchymal stem cells were isolated from bone marrow aspirated from 10 patients and cultured on allografts from five donors (Group 2), producing 50 samples. This was repeated on allografts heat-treated to denature bioactive proteins (Group 1), and repeated again on allografts to which osteogenic supplements (Group 3) were added. Group 2 mesenchymal stem cells differentiated into osteoblasts producing higher levels of alkaline phosphatase, osteopontin, and Type I collagen matrix protein than Group 1. The rate of differentiation of Group 3 mesenchymal stem cells increased with the supplements. Overall, it was established that the bioactive proteins in the allograft stimulated mesenchymal stem cell differentiation into osteoblasts, with production of extracellular matrix, and that this differentiation increased with the addition of osteogenic supplements.

Primary giant cell tumours of the digital bones of the hand

Primary giant cell tumours involving digital bones of the hand are rare lesions which are generally diagnosed at an advanced stage. Accurate diagnosis requires clinical evaluation, imaging studies and histopathological assessment. Conservative treatment by digit-sparing surgery is associated with high recurrence rates. In a ten year retrospective review, this study identified only four cases. Three cases involved a phalanx and were treated by distal amputation of the involved digit. None recurred. One involved the metacarpal and recurred twice following repeated curettage and bone grafting. No further recurrence has been detected after resection and replacement with a non-vascularised fibular graft and Silastic implant replacement of the metacarpophalangeal joint. Our small series of cases supports a policy of aggressive primary surgery, including amputation or en bloc resection and reconstruction.

Topographical variation in glycosaminoglycan content in human articular cartilage

The weight-bearing status of articular cartilage has been shown to affect its biochemical composition. We have investigated the topographical variation of sulphated glycosaminoglycan (GAG) relative to the DNA content of the chondrocyte in human distal femoral articular cartilage. Paired specimens of distal femoral articular cartilage, from weight-bearing and non-weight-bearing regions, were obtained from 13 patients undergoing above-knee amputation. After papain enzyme digestion, spectrophotometric GAG and fluorometric DNA assays assessed the biochemical composition of the samples. The results were analysed using a paired t-test. Although there were no significant differences in cell density between the regions, the weight-bearing areas showed a significantly higher concentration of GAG relative to DNA when compared with non-weight-bearing areas (p = 0.02). We conclude that chondrocytes are sensitive to their mechanical environment, and that local loading conditions influence the metabolism of the cells and hence the biochemical structure of the tissue.

Hibernoma: MRI features in eight consecutive cases

AIM

To describe the preoperative magnetic resonance imaging findings of eight histologically-proven cases of hibernoma.

MATERIALS AND METHODS

The site, size, and signal characteristics of eight consecutive hibernomas were retrospectively assessed on T1-weighted spin-echo and short T1 inversion recovery (STIR)/fat-saturated T2-weighted fast spin echo magnetic resonance images. Four patients also had gadolinium-enhanced fat-saturated T1-weighted spin echo imaging. Patient age and sex, and duration of symptoms were recorded.

RESULTS

Three female and five male patients with an average age 36 years (range 16-53 years) were included. Seven lesions occurred in the thigh, four in the anterior compartment and three in the posterior compartment. One lesion occurred superficial to the scapula. All cases demonstrated common magnetic resonance imaging findings of a well-defined, heterogeneous mass, slightly or clearly hypo-intense to subcutaneous fat on T1-weighted spin-echo images, with prominent thin low signal bands throughout the tumour. The lesions failed to fully suppress on STIR or fat-saturated T2-weighted images. Only one of the four contrast-enhanced studies demonstrated increased vascularity in the tumour.

CONCLUSION

The MRI findings of a lesion that is diffusely slightly hypointense to surrounding subcutaneous fat, should prompt the operator to consider hibernoma in the differential diagnosis.

A knee-sparing distal femoral endoprosthesis using hydroxyapatite-coated extracortical plates

We used a knee-sparing distal femoral endoprosthesis in young patients with malignant bone tumours of the distal femur in whom it was possible to resect the tumour and to preserve the distal femoral condyles. The proximal shaft of the endoprosthesis had a coated hydroxyapatite collar, while the distal end had hydroxyapatite-coated extracortical plates to secure it to the small residual femoral condylar fragment. We reviewed the preliminary results of this endoprosthesis in eight patients with primary bone tumours of the distal femur. Their mean age at surgery was 17.years (14 to 21). The mean follow-up was 24 months (20 to 31). At final follow-up the mean flexion at the knee was 102° (20° to 120°) and the mean Musculoskeletal Tumour Society score was 80% (57% to 96.7%).

There was excellent osteointegration at the prosthesis-proximal bone interface with formation of new bone around the hydroxyapatite collar. The prosthesis allowed preservation of the knee and achieved a good functional result. Formation of new bone and remodelling at the interface make the implant more secure. Further follow-up is required to determine the long-term structural integrity of the prosthesis.

Massive endoprostheses for giant cell tumours of the distal femur: A 12-year follow-up

We performed a retrospective analysis of twenty-five consecutive massive articulating endoprostheses that were inserted at our unit during the management of patients with Giant Cell Tumours of their distal femur. Fifteen of these implants were fixed hinge devices and ten were rotating hinge devices with HA collars (since 1993). None of these cases were revised for sepsis. There had been no cases of recurrent disease or amputation. The mean follow-up was 12 years (range = 5-18 years). The average age at time of insertion was 37 years. Young patients with fixed hinged devices developed a high incidence (33%) of aseptic loosening. They also had a significant rate of re-bushing. Results of the rotating hinge prosthesis with HA collar were much more promising. Functional scores were good after a period of 12 years despite the young age group.

Diffuse pigmented villonodular synovitis of the foot and ankle treated with surgery and radiotherapy

We followed up seven patients with histologically confirmed diffuse pigmented villonodular synovitis in a prospective study between 1992 ans 2001. The mean age at diagnosis was 30.7 years. The patients underwent synovectomy, followed by radiotherapy with a total dose of 35 Gy in 20 fractions. In all cases, the excision was considered incomplete when examined histologically. At an average follow up of 24 (18-36) months, six patients reported better function and reduced levels of pain. One patient remained symptomatic but did not have a recurrence. We conclude that a combined approach to a primary pigmented villonodular synovitis of the foot and ankle may reduce the risk of recurrence without functional impairment.

The novel use of resorbable Vicryl mesh for in vivo tendon reconstruction to a metal prosthesis

We examined the mechanical properties of Vicryl (polyglactin 910) mesh in vitro and assessed its use in vivo as a novel biomaterial to attach tendon to a hydroxyapatite-coated metal implant, the interface of which was augmented with autogenous bone and marrow graft. This was compared with tendon re-attachment using a compressive clamp device in an identical animal model. Two- and four-ply sleeves of Vicryl mesh tested to failure under tension reached 5.13% and 28.35% of the normal ovine patellar tendon, respectively. Four-ply sleeves supported gait in an ovine model with 67.05% weight-bearing through the operated limb at 12 weeks, without evidence of mechanical failure.

Mesh fibres were visible at six weeks but had been completely resorbed by 12 weeks, with no evidence of chronic inflammation. The tendon-implant neoenthesis was predominantly an indirect type, with tendon attached to the bone-hydroxyapatite surface by perforating collagen fibres.

Autotransfusion drains in total knee replacement. Are they alternatives to homologous transfusion?

We prospectively randomised 104 consecutive patients undergoing primary cemented total knee arthroplasty into two groups of 52 patients each, with one group to receive a standard suction drain (Redivac) and the other, an autologous transfusion drain (Bellovac). Randomisation was achieved using the software programme MINIM: , which was set to randomly allocate patients to either of the two groups based on their age, sex and body mass index (BMI). All procedures were performed under pneumatic tourniquet. Drains were released in the recovery room 20 min after surgery and removed 24 h following surgery. Blood collected in the standard suction drain (control group) was discarded, while blood collected in the autologous transfusion drains (study group) was transfused unwashed back to the patient within 6 h of collection. Thirteen patients (25%) in the study group had two or more units of homologous blood transfused in addition to the blood collected postoperatively and re-transfused (average: 438 ml). Twelve patients (23%) in the control group had two or more units of homologous blood transfused. No sepsis, transfusion reactions or coagulopathies were associated with the autologous blood transfused in the study group. The use of the autologous transfusion system (Bellovac) proved to be safe but failed to reduce the need for postoperative homologous blood transfusion following uncomplicated total knee arthroplasty.

Stanmore non-invasive growing arthrodesis endoprosthesis in the reconstruction of complicated total knee arthroplasty: A case report

As the number of primary and revision arthroplasties performed each year increases, the complexity of the reconstructive efforts also increases. A case of a patient with a total knee arthroplasty complicated with infection, deficient extensor mechanism, bone loss and limb shortening of 5.5 cm is reported. We describe an alternative surgical technique of reconstruction of the knee and lengthening of the limb using the Stanmore Non-Invasive Growing-Distal Femoral Prosthesis. The prosthesis had a magnetic disc attached to a gearbox. The generation of an external electromagnetic field caused the magnetic disc to rotate and lengthen the prosthesis. This reconstructive technique has not been described in the literature.

Osteofibrous dysplasia of the tibia

Osteofibrous dysplasia is an unusual developmental condition of childhood, which almost exclusively affects the tibia. It is thought to follow a slowly progressive course and to stabilise after skeletal maturity. The possible link with adamantinoma is controversial and some authors believe that they are part of one histological process.

We retrospectively reviewed 16 patients who were diagnosed as having osteofibrous dysplasia initially or on the final histological examination. Their management was diverse, depending on the severity of symptoms and the extent of the lesion. Definitive (extraperiosteal) surgery was localised ‘shark-bite’ excision for small lesions in five patients. Extensive lesions were treated by segmental excision and fibular autograft in six patients, external fixation and bone transport in four and proximal tibial replacement in one. One patient who had a fibular autograft required further excision and bone transport for recurrence. Six initially underwent curettage and all had recurrence. There were no recurrences after localised extraperiosteal excision or bone transport. There were three confirmed cases of adamantinoma.

The relevant literature is reviewed. We recommend extraperiosteal excision in all cases of osteofibrous dysplasia, with segmental excision and reconstruction in more extensive lesions.

Non-invasive distal femoral expandable endoprosthesis for limb-salvage surgery in paediatric tumours

We report our early experience with the use of a non-invasive distal femoral expandable endoprosthesis in seven skeletally immature patients with osteosarcoma of the distal femur. The patients had a mean age of 12.1 years (9 to 15) at the time of surgery. The prosthesis was lengthened at appropriate intervals in outpatient clinics, without anaesthesia, using the principle of electromagnetic induction. The patients were functionally evaluated using the Musculoskeletal Tumour Society scoring system. The mean follow-up was 20.2 months (14 to 30). The prostheses were lengthened by a mean of 25 mm (4.25 to 55) and maintained a mean knee flexion of 110° (100° to 120°). The mean Musculoskeletal Tumour Society score was 68% (11 to 29). Complications developed in two patients; one developed a flexion deformity of 25° at the knee joint, which was subsequently overcome and one died of disseminated disease. The early results from patients treated with this device have been encouraging. The implant avoids multiple surgical procedures, general anaesthesia and assists in maintaining leg-length equality.

Interobserver variation in the measurement of patellar height after total knee arthroplasty

We assessed the reproducibility and accuracy of four ratios used to measure patellar height, namely the Blackburne-Peel, Caton-Deschamps, Insall-Salvati and modified Insall-Salvati, before and after total knee arthroplasty. The patellar height was measured, by means of the four ratios, on the pre- and post-operative lateral radiographs of 44 patients (45 knees) who had undergone total knee arthroplasty. Two independent observers measured the films sequentially, in identical conditions, totalling 720 measurements per observer. Statistical analysis, comparing both observers and ratios, was carried out using the intraclass correlation coefficient.

Before operation there was greater interobserver variation using either the Insall-Salvati or modified Insall-Salvati ratios than when using the Caton-Deschamps or Blackburne-Peel methods. This was because of difficulty in identifying the insertion of the patellar tendon. Before operation, there was a minimal difference in reliability between these methods. After operation the interobserver difference was greatly reduced using both the Caton-Deschamps and Blackburne-Peel methods, which use the prosthetic joint line, compared with the Insall-Salvati and modified Insall-Salvati, which reference from the insertion of the patellar tendon.

The theoretical advantage of using the Insall-Salvati and modified Insall-Salvati ratios in measuring true patellar height after total knee arthroplasty needs to be balanced against their significant interobserver variability and inferior reliability when compared with other ratios.

Extensor mechanism reconstruction after proximal tibial replacement

We developed an in vivo model of the attachment of a patellar tendon to a metal implant to simulate the reconstruction of an extensor mechanism after replacement of the proximal tibia. In 24 ewes, the patellar tendon was attached to a hydroxyapatite (HA)-coated titanium prosthesis. In 12, the interface was augmented with autograft containing cancellous bone and marrow. In the remaining ewes, the interface was not grafted.

Kinematic gait analysis showed nearly normal function of the joint by 12 weeks. Force-plate assessment showed a significant increase in functional weight-bearing in the grafted animals (p = 0.043). The tendon-implant interface showed that without graft, encapsulation of fibrous tissue occurred. With autograft, a developing tendon-bone-HA-implant interface was observed at six weeks and by 12 weeks a layered tendon-fibrocartilage-bone interface was seen which was similar to a direct-type enthesis.

With stable mechanical fixation, an appropriate bioactive surface and biological augmentation the development of a functional tendon-implant interface can be achieved.

Metal ion levels after metal-on-metal proximal femoral replacements

Metal-on-metal hip bearings are being implanted into younger patients. The consequence of elevated levels of potentially carcinogenic metal ions is therefore a cause for concern. We have determined the levels of cobalt (Co), chromium (Cr), titanium (Ti) and vanadium (Va) in the urine and whole blood of patients who had had metal-on-metal and metal-on-polyethylene articulations in situ for more than 30 years. We compared these with each other and with the levels for a control group of subjects.

We found significantly elevated levels of whole blood Ti, Va and urinary Cr in all arthroplasty groups. The whole blood and urine levels of Co were grossly elevated, by a factor of 50 and 300 times respectively in patients with loose metal-on-metal articulations when compared with the control group. Stable metal-on-metal articulations showed much lower levels. Elevated levels of whole blood or urinary Co may be useful in identifying metal-on-metal articulations which are loose.