KWK Ho, JCF Lau and S Sadiq examine the use of the Cannulok Plus hip system in the management of complex proximal femur fractures
Abstract
Complex proximal femoral fractures secondary to metastatic destruction and peri-prosthetic fractures in the elderly patient is a major management challenge. The principle treatment involves using a prosthesis that will endure the lifespan of the patient. Our objective is to review the results of a cannulated hip system in the management of these complex conditions.
A series of 19 patients aged between 50 and 102 years old (mean 78+/-13.5SD) was managed with an implantation of a fully hydroxyapatite coated and distally locked cannulated hip prostheses. 63% (12/19) were indicated due to Vancouver type B2 and B3 periprosthetic fractures of hip arthroplasty. 11% (2/19) of patients had associated metastatic bone disease, and the remaining cases were due to other pathologies associated with inadequate proximal bone stock. Primary outcome is the longevity of the implants with revision for any cause as the end point. Secondary outcome included operative complications, fracture union, length of in-patient stay and place of discharge.
Seven patients (36.8%) died from an unrelated cause at six months minimum follow-up and none of them required further revision surgery. The mean survival of the prosthesis in this group was 234 days (+/-328 SD). 12 patients still had a functional weight-bearing hip at the last review and were discharged back to their home environment. The mean survival of the prosthesis in this group was 827 days (+/-525 SD). Implant survival was 87% with revision for any reason as the end point and 100% for femoral implant revision. Five patients suffered surgical complications; three of which were hip dislocations. Of these, two required revision surgery and the other required closed manipulation. Cables and wires were used as augmentation on nine hips and distal locking screws were used on 15 hips.
In our study, 84% did not require further surgery with this prosthesis. Considering the age of this group, a high rate of mortality and morbidity was to be expected. However, none of the deceased patients required additional surgery. We found the Cannulok Plus hip system to be a valid option in the management of these conditions and to have a low chance of further surgery.
Introduction
It is estimated that over 70,000 proximal hip fractures occur annually in the UK and this figure has been projected to rise to 91,500 by 2015 and 101,000 in 20201-2. This is usually due to a fragility fracture caused by a fall affecting an older person with osteoporosis or osteopenia. Currently, the average age of a hip fracture patient is 77 years and is increasing every year1.
This phenomenon, together with the increased demand for hip replacement surgery, has resulted in a rising incidence of periprosthetic hip fractures3. The management of these complex fractures in the elderly consist of medical treatment as well as an operative option using prostheses with sufficient longevity to outlast the lifespan of the patients. In order to facilitate this multi-disciplinary care approach, the surgical implant should provide sufficient stability to allow early weight bearing and mobilisation. Ease of instrumentation, low revision rate and cost-effectiveness are also significant factors to consider.
In our hospital we used the Cannulok Plus hip system (Orthodynamics Ltd, Gloucestershire, UK) which has been found useful in revision hip or complex primary arthroplasty with insufficient proximal bone stock4. It is an extensively coated femoral stem with a variable length option. It also has three distal locking screws, thereby allowing the implant to be fixed distally to improve rotational and axial stability; this facilitates load transfer to stronger intact diaphyseal bone and allows early weight-bearing. There are various modular head options ranging from 22mm to bi-polar head prostheses. However, the effectiveness of these prostheses have not been evaluated within our department.
Our objective is to review the results of the Cannulok Plus hip system in the management of complex proximal femur fractures.
Methods
All of the complex proximal femoral fractures that were treated with the Cannulok Plus hip system were reviewed. All of the cases were performed by the senior author between 2007 and 2011. Our selection criteria included those patients with a Vancouver type B2 and B3 peri-prosthetic fracture5, pathological fractures of the proximal femur secondary to metastatic bone disease, and complex fractures of the proximal femur with deficient proximal bone stock. Those with intra-capsular fractures of the hip with minimal evidence of osteoarthritis, inter-trochanteric fracture of the femur, Vancouver type A, B1 and C, abnormal femoral anatomy that would be better suited with an offset femoral stem were excluded.
19 patients (7 males and 12 females) with a mean age of 78 years (+/-13.5 SD) met our selection criteria and detailed information of these patients was retrieved from the hospital centralised computer system and patient notes. Table 1 showed the basic demographic of the study group. The following data were recorded for each patient: an assessment of the patient’s walking ability indoors and outdoors, American Society of Anesthesiologists (ASA) grade6 (1, normal healthy individual; 2, mild systemic disease that does not limit activity; 3, severe systemic disease that limits activity but is not incapacitating; 4, incapacitating systemic disease which is constantly life-threatening; 5, moribund: not expected to survive 24 hours with or without surgery; or unknown), length of hospital stay, patient’s status at discharge and the level of mobility.
The acetabular component was revised if there was evidence of loosening at the time of surgery. A modular bi-polar head articulation was used if the peri-prosthetic fracture occurs in a patient with existing hemiarthroplasty or in patients with increase risk of hip dislocation; we believed the use of modular bi-polar head would convey more hip stability and a shorter operative time.