Professional Guidelines Included
Learn the Navigated coned hemi-pelvis endoprosthesis (Stanmore METS, Stryker) with dual mobility acetabulum (Avantage, Zimmer Biomet) and modular proximal femoral endoprosthetic replacement with trochanteric reattachment (Stanmore METS, Stryker) surgical technique with step by step instructions on OrthOracle. Our e-learning platform contains high resolution images and a certified CME of the Navigated coned hemi-pelvis endoprosthesis (Stanmore METS, Stryker) with dual mobility acetabulum (Avantage, Zimmer Biomet) and modular proximal femoral endoprosthetic replacement with trochanteric reattachment (Stanmore METS, Stryker) surgical procedure.
Computer navigated tumour surgery is regarded as one of the major developments in the field of orthopaedic oncology of the past decade. Navigation permits pre-operative three-dimensional resection and implant planning to be combined with intra-operative imaging. These advantages have resulted in its growing incorporation into routine practice since its first application in 2004. In this case I describe the use of navigation to aid endoprosthetic reconstruction of the pelvis and acetabulum using the Stanmore coned semi-pelvis (‘ice cream cone’) endoprosthesis (http://www.stanmoreimplants.com/downloadpdfs/06.METS%20Coned%20Hemi-Pelvis%20Information%20and%20Surgical%20Procedures%20(File%20Size%20-%201MB).pdf).
This implant is ‘off the shelf’ and utilised in orthopaedic oncology to reconstruct the peri-acetabulum due to bone loss due to tumour involvement. Pelvic anchoring is provided by a fixed hydroxyapatite stem which can augmented with bone cement and reinforced with screws to achieve a stable acetabular reconstruction. Having created the acetabulum, a suitable acetabular cup is cemented into the cone for use with a total hip replacement. Recent evidence has confirmed that dual-mobility articulations reduce the risk of dislocation with hemi-pelvic endoprostheses, so this case describes the use of a cemented dual-mobility acetabular cup and bearing.
Metastatic bone disease commonly presents to the orthopaedic surgeon. Bone is the most common site of metastasis. Approximately 60% to 70% of patients with breast cancer develop bone metastases during the course of their disease. Skeletal related events (SREs: pathological or impending fracture, hypercalcaemia, spinal cord compression, severe pain) may require surgery and/or radiotherapy to palliate pain and to maintain both the capacity to walk and quality of life. Due to advances in management of common malignancies, particularly breast and prostate carcinoma, patient survival has been extended to the point that these are now considered chronic diseases rather than terminal diseases. Consequently, the prevalence of metastatic bone disease continues to escalate.
Indications
The indications to use the ice cream cone prosthesis are to reconstruct defects after resection of malignant periacetabular tumours or defects caused by the removal of a previous failed pelvic reconstruction in order to preserve mobility and provide pain relief. Pelvic resections can be divided by the Enneking classification into P1 (ileum), P2 (periacetabulum) and P3 (pubic/ischium) and P4 (hemi-sacrum). The ice cream cone stem is inserted into the residual ileum thus bypassing the periacetabular defect caused by excision or pathological fracture. In order to avoid some of the mechanical complications associated with misplacement of the ice cream cone (Fisher et al. J Bone Joint Surg [Br] 2011;93:684-8.), navigation is a useful adjunct to optimise implant positioning.
Symptoms & Examination:
Patients with periacetabular metastases present with increasing groin or buttock pain and difficulty bearing weight, often necessitating walking aids. Following pathological acetabular fracture a sudden increase in pain and decrease in walking ability culminating in emergency hospital admission would be anticipated. Clinically the presentation mimicks a fractured hip but following radiographs in the emergency department highlighting a pathological acetabular fracture, referral to a specialist orthopaedic oncology centre for consideration of reconstruction would be advocated.
Investigations:
In order to assess the patients suitability for major surgery, a detailed understanding of the underlying malignant process is necessary. Assuming that the patient is known to have had a recent diagnosis of carcinoma, a staging CT chest abdomen and pelvis to establish the extent of metastases in the lungs and abdominal viscera and whole-body bone scintigraphy would be done to assess the extent of skeletal disease, plus routine blood tests particularly the bone profile to exclude hypercalcaemia. If the underlying malignant diagnosis is unknown then the same inmates would be done to identify and potentially biopsy the primary tumour. In both cases a discussion with the oncology team and and tissue specific multi-disciplinary team to stage the patient appropriately before considering surgical intervention for the hip. More detailed guidelines on the investigation and management of metastatic bone disease are available from the British Orthopaedic Oncology Society guideline update 2015 (http://www.boos.org.uk/wp-content/uploads/2016/03/BOOS-MBD-2016-BOA.pdf).
Assuming the staging investigations have been completed and the patient is deemed suitable for surgery both pelvic MRI and CT are required to delineate the extent of the pelvic metastasis and fracture. The CT scan is pre-loaded onto the navigation 3 system (Stryker, Kalamazoo, Michigan, USA) to enable the surgeon to plan the trajectory for the insertion of the ice cream cone stem into the posterior ileum aiming to optimise the position of the cup face level with the native acetabulum (using Orthomap 3D software).
Non-operative management:
In general radiotherapy can be used for symptomatic periacetabular metastases to control symptoms, particularly in patients unsuitable for surgery. However this may not control the symptoms from a pathological acetabular fracture.
Alternative surgical operations:
Conventionally, for contained acetabular metastases, patients would have curettage of the tumour from within the acetabulum and a cemented total hip replacement followed by post-operative radiotherapy. One alternative for more extensive defects might be the Harrington rod technique (Tillman et al. J Bone Joint Surg [Br] 2008;90:84-7.): three 6.5mm Harrington rods can be inserted from the iliac crest to ischium/pubis to enable conventional cemented acetabular cup insertion. In this particular case the patient had disease involvement of the iliac wing, therefore the ice-cream cone was selected. Other general options for acetabular metastases (but not suitable for this case) might include custom pelvic endoprostheses, cementoplasty and acetabular cages used in revision hip arthroplasty.
Contraindications:
Conventional curettage and cemented acetabular resurfacing were contraindicated in this case due to the extent of the disease throughout the ileum to the sciatic notch. Absolute contraindications for the use of the ice-cream cone are the same as total hip arthroplasty i.e. infection, insufficient bone stock in the ileum, and medical unsuitability for example due to extensive pulmonary metastases.
Therefore the patient was consented for an ‘ice-cream cone’ type pelvic endoprosthesis and total hip replacement. Risks are identical to conventional hip arthroplasty although the level of risk is greater given the length and magnitude of the surgical procedure and the need for post-operative radiotherapy (infection). Having cancer of course also pre-disposes patients to thrombosis.
HDU care, distal neurovascular observations
24 hours post-operative IV antibiotic prophylaxis
VTE: early mobilisation, LMWH 6 hours post-operatively for 4 weeks, thigh length TED stockings 6 weeks and foot pumps until mobile
Routine X-ray AP pelvis and AP & lateral femur
Await histology result and then post-operative radiotherapy by local oncology team at six weeks post-operatively
Clip removal 2 weeks
We manage these patients like revision hips replacements in terms of rehabilitation with physiotherapy guidance as an inpatient plus walking aids. Following discharge from hospital they would be seen in outpatients at 6 weeks routinely, then at 6 months post-operatively then annually unless their metastatic disease burden prevented them from attending outpatients. Oncologically, once the histology is confirmed, post-operative radiotherapy is usually advocated (unless they have previously received radiotherapy and further treatment would exceed tissue tolerances) and then their oncological management resides with their local team.
Short-term outcomes for the Stanmore METS ice-cream cone endoprosthesis (Matharu GS, et al. Severe pelvic bone loss treated using a coned acetabular prosthesis with a stem extension inside the ilium. Acta Orthop Belg. 2013 Dec;79(6):680-8)
Complications with the use of an ice-cream cone prosthesis have been described as including deep infection (4%) and dislocation (12%) although this series did not utilise a dual-mobility acetabular component as used in this case to reduce the risk of dislocation.
Bus et al. LUMiC® Endoprosthetic Reconstruction After Periacetabular Tumor Resection: Short-term Results. Clin Orthop Relat Res. 2017 Mar;475(3):686-695. doi: 10.1007/s11999-016-4805-4.
Bus et al. reported a 4% dislocation rate using dual mobility cups compared to 39% with conventional hip replacement articulations with an ice cream cone type prosthesis (13% overall). Indications for revision surgery were instability (2%), loosening (6%), and infection (9%).
Stihsen et al. Review of the outcomes of complex acetabular reconstructions using a stemmed acetabular pedestal component. Bone Joint J 2016;98-B:772–9
Stihsen et al. reported 17% revision for aseptic loosening and 11% revision for infection and 6% for technical failure (e.g. pelvic perforation) at mean 5 years.
Fujiwara et al. Acetabular reconstruction with an ice-cream cone prosthesis following resection of pelvic tumours. Journal of Surgical Oncology 2020; doi.org/10.1002/jso.25882
Navigated ice-cream cones had lower incidence of major complications and superior functional outcomes compared to non-navigated reconstructions.
Reference
- orthoracle.com
