Aims

Rotating-hinge knee prostheses are commonly used to reconstruct the distal femur after resection of a tumour, despite the projected long-term burden of reoperation due to complications. Few studies have examined the factors that influence their failure and none, to our knowledge, have used competing risk models to do so. The purpose of this study was to determine the risk factors for failure of a rotating-hinge knee distal femoral arthroplasty using the Fine-Gray competing risk model.

Aims

Although internal hemipelvectomy is associated with a high incidence of morbidity, especially wound complications, few studies have examined rates of wound complications in these patients or have identified factors associated with the consequences. The present study aimed to: 1) determine the rate of wound and other complications requiring surgery after internal hemipelvectomy; and 2) identify factors that affect the rate of wound complications and can be used to stratify patients by risk of wound complications.

A retrospective analysis was performed of eight patients with an open triradiate cartilage, who underwent resection for osteosarcoma and reconstruction of the proximal femur with a hemiarthroplasty, in order to identify changes of acetabular development. An analysis of the centre-edge angle, teardrop-to-medial prosthesis distance, superior joint space, teardrop-to-superior prosthesis distance, degree of lateral translation, and arthritic changes, was performed on serial radiographs. The median age at the time of the initial surgery was 11 years (5 to 14).

All patients developed progressive superior and lateral migration of the prosthetic femoral head. Following hemiarthroplasty in the immature acetabulum, the normal deepening and enlargement of the acetabulum is arrested. The degree of superior and lateral migration of the prosthetic head depends on the age at diagnosis and the length of follow-up.

Introduction: Patients with spinal metastases often have patterns of disease requiring both an anterior and posterior surgical decompression and stabilisation. Subtotal spondylectomy and circumferential stabilisation can be safely performed via a single posterior transpedicular approach. Polymethyl-methacrylate bone cement (PMMA) has been widely used in spinal column reconstruction with mixed results. PMMA is a potential means for local drug delivery in the prevention of locally recurrent disease. The biomechanical characteristics of anterior reconstruction using PMMA have not been adequately evaluated.

Purpose: To evaluate the stability of an anterior cement construct following total spondylectomy and to compare this reconstruction against alternative stabilisation techniques.

Methods: Ten fresh-frozen human cadaveric spines (T9-L3) were used. After intact analysis, a total spondylectomy was performed at T12. Three potential reconstruction techniques were tested for their ability to restore stiffness to the specimen: (1) multi-level posterior pedicle screw instrumentation from T10-L2 {MP1} [Depuy Acromed], (2) anterior instrumentation [ATL Z-plate II™, Medtronic, Sofamor Danek Instruments] and rib graft at T11-L1 with multi-level posterior instrumentation from T10-L2 {AMPI}, and (3) anterior cement [Simplex P] and pins construct (T12) with multi-level posterior instrumentation from T10-L2 {CMPI}. Each of the three potential reconstruction techniques was tested on each specimen in random order. Non-destructive testing was performed under load control. The specimen was positioned vertically for axial compression and torsion testing, and horizontal for flexion/extension and lateral bending tests. A customised jig was manufactured for this latter purpose.

Results: Only circumferential stabilisation techniques (AMPI, CMPI) restored stiffness to a level equivalent or higher to that of the intact spine in all loading modes (p< 0.05). CMPI provided more stability to the specimen than AMPI in compression and flexion testing (p< 0.05). Posterior instrumentation alone (MPI) did not restore stiffness to the intact level in compression and flexion testing (p< 0.005).

Conclusions: Circumferential reconstruction using an anterior cement construct provides equal or more stability than the intact spine in all testing modes. Posterior stabilisation alone is an inadequate method of reconstruction following total spondylectomy. PMMA has the advantage over traditional anterior reconstruction techniques in that it can be inserted using a single posterior approach and offers the potential value of local drug delivery.

To evaluate and compare the stability of an anterior cement construct following total spondylectomy for meta-static disease against alternative stabilization techniques.

After intact analysis of ten cadaveric spines (T9–L3), a T12 spondylectomy was performed. Three reconstruction techniques were tested for their ability to restore stiffness to the specimen using non-destructive tests:

1) multilevel posterior pedicle screw instrumentation (PPSI) from T10–L2 {MPI}, 2) anterior instrumentation from T11–L1 with PPSI {AMPI}, and 3) anterior cement and pins construct (T12) with PPSI {CMPI}.

Circumferential stabilization {AMPI, CMPI} restored stiffness to a level of the intact spine. CMPI provided more stability to the specimen than AMPI. MPI alone did not restore stiffness to the intact level.

Circumferential reconstruction using an anterior cement construct following total spondylectomy is biomechanically superior to posterior stabilisation alone.