To The Editor:

I congratulate the authors on performing a randomized, controlled trial concerning a very important issue(1). It is an excellent contribution.

While studying the paper, I noted that in reference to the self- reported walking distance (one of the statistically significant differences between the groups), the range of distances for the total hip arthroplasty patients was 0 to 25 miles. Do the authors believe that one of their THA patients could indeed walk 25 miles at a single time? Importantly, if that outlier were removed from the calculation of the average walking distance, would there still be a significant difference between the groups?

The author did not receive any outside funding or grants in support of his research for or preparation of this work. Neither he nor a member of his immediate family received payments or other benefits or a commitment or agreement to provide such benefits from a commercial entity. No commercial entity paid or directed, or agreed to pay or direct, any benefits to any research fund, foundation, division, center, clinical practice, or other charitable or nonprofit organization with which the author, or a member of his immediate family, is affiliated or associated .

Reference:

1. RP Baker, B Squires, MF Gargen, GC Bannister. Total hip arthroplasty and hemiarthroplasty in mobile, independent patients with a displaced intracapsular fracture of the femoral neck. A randomized, controlled trial. J Bone Joint Surg Am. 2006;88:2583-2589.

Thank you for your kind comments and interest in our paper (1)

1. The 7.5% dislocation rate might have been improved a little by using a 32 mm head. Other variables that could have reduced the dislocation rate were optimal orientation of the acetabular component, use of an acetabular component with a long posterior wall, and repair of the transgluteal approach in three layers that include the capsule, gluteus medius and gluteus minimus.

2. The suggestion that a 1 mm uni-polar head might reduce acetabular erosion is entirely justified. D’Arcy and Devas(2) noted an 11% prevalence of acetabular erosion when using acetabular componenets with increments of 1/8th inch (3.2 mm). They subsequently went on to develop a bi-polar hip with 1 mm increments that had a much lower erosion rate(3). However,this modification had 2 variables, the first being change in increment of head size, and the second the bi-polar design, so the specific influence of the 1 mm increment alone cannot be isolated.

A larger uni-polar femoral head was associated with a higher erosion rate in D’Arcy and Devas’ paper(2) so we would not recommend this from their experience.

3. The Oxford outcome measure is self reported but validated and as patients describe symptoms we feel that patient orientated functional outcome measures should replace those derived from physicians.

We agree with the authors that the displaced intracapsular femoral neck fracture remains an unsolved injury, particularly in younger patients. We hope our study has made a small contribution to clarifying the management in mobile independent older patients.

References:

1. Baker RP, Squires B, Gargan MF, Bnnister GC. Total hip arthroplasty and hemiarthroplasty in mobile, independent patients with a displaed intracapsular fracture of the femoral neck. A randomized controlled trial.

2. D’Arcy J, Devas M. Treatment of fractures of the femoral neck by replacement with the Thompson prosthesis. J Bone Joint Surg. 1976:58B:279-286.

3. Devas M, Hinves B. Prevention of acetabular erosion after hemi- arthroplasty for fractured neck of femur. J Bone Joint Surg. 1983:65B:548 -551

To The Editor:

Upon reading the Level 1 Evidence study comparing hemiarthroplasty to total hip arthroplasty for the treatment of displaced femoral neck fractures in the active elderly(1), I wanted to write to congratulate the authors for an excellent study regarding an important topic. Coincidentally, a consortium of US surgeons (DFACTO, Displaced Femoral neck fracture Arthroplasty Consortium for Treatment and Outcomes) has performed a similar study with strikingly similar results, which in November 2006, was submitted for publication to the JBJS British.

I have some thoughts and questions which perhaps we can ask the authors can comment on:

1) In regards to the 7.5% dislocation rate reported in their study, it would appear from the Methods section that for the total hips, a 28 mm prosthetic head was placed using a transgluteal approach to the hip, without a capsular repair in all cases. Do the authors feel that the use of larger prosthetic femoral heads (32 mm and above) with a capsular repair upon closure would have decreased this dislocation rate?

2) The finding that 66% of the hemiarthroplasty patients demonstrated some degree of acetabular erosion during the follow-up period was impressive, but I cannot help but wonder if the use of modular unipolar heads in 1 mm size increments would have reduced the prevalence of acetabular erosion. During the performance of hemiarthroplasty of the hip for my patients, I prefer to implant the largest unipolar femoral head possible in order for the intact labrum to bear some of the stress during ambulation and hip movement.

3) Results from our DFACTO Trial also found that patients who were randomized to total hip arthroplasty had a higher likelihood of increased ability to ambulate when compared to hemiarthroplasty. However, we preferred the use of the objective (non-patient reported) measure known as the Timed Up & Go (TUG) test . One of the potential criticisms of all these trials is that it is very difficult to blind the patient to the treatment; thus self-reported outcomes must, therefore, be looked at skeptically due to higher potential bias.

The magnitude of the importance of this kind of work cannot be overstated. While I am less familiar with the demographics of the elderly population of the UK, in the US, we currently care for more than 350,000 hip fractures each year. This number is expected to double by 2040. The surgical outcome of each procedure must be optimized to keep our respective health care systems from being excessively burdened with complications and re-operations. Baker et al. have correctly pointed out that the outcomes of an older, less independent population of patients remains more in question (though the application of capsular repair and enhanced head-to-neck ratio for THA may allow a more widespread application of THA for the treatment of femoral neck fractures).

I challenge our colleagues who treat displaced femoral neck fractures throughout the world to also consider more the optimal treatment of similar patients below the age of 60, particularly those with a 2 day interval from trauma to treatment, comminution of the femoral neck, a high degree of displacement, and poor bone quality.

The author did not receive any outside funding or grants in support of his research for or preparation of this work. Neither he nor a member of his immediate family received payments or other benefits or a commitment or agreement to provide such benefits from a commercial entity. No commercial entity paid or directed, or agreed to pay or direct, any benefits to any research fund, foundation, division, center, clinical practice, or other charitable or nonprofit organization with which the author, or a member of his immediate family, is affiliated or associated .

Reference:

1. Baker RP, Squires B, Gargan MF, Bannister GC. Total hip arthroplasty and hemiarthroplasty in mobile, independent patients with a displaced intracapsular fracture of the femoral neck. A randomized, controlled trial. J Bone Joint Surg Am 2006;88:2583-2589.