We would firstly like to thank Dr. Marsh for his overall positive remarks in the Commentary and Perspective that was published on the Journal's web site on our paper "Dynamic Hip Screw Compared with External Fixation for Treatment of Osteoporotic Pertrochanteric Fractures" We would, however, also like to draw Dr. Marsh's attention to a few points, which we feel deserve some clarification.

In contrast to what Dr. Marsh stated, we found that the Orthofix Pertrochanteric Fixator (OPF) provides better and different outcomes in femoral neck-shaft angle (FNSA) at 6 months as compared with the sliding hip screw group. Furthermore, fracture reduction was better maintained in the OPF group than in the SHS group, as shown by significantly lower fracture varusization at 6 months vs postop.

Concerning the possible increase in pain for the removal of the well- fixed HA-coated pins, this may be a problem for patients with good quality bone but, for the osteoporotic patient it is not. In a previous study of osteoporotic wrist fractures, we quantified pain during pin removal and no differences between standard and HA-coated pins were noted (1).

We completely agree that other implants such as intramedullary hip screw may be better alternatives than external fixation for treatment of unstable pertrochanteric fractures. However, particularly with these fractures, we are rather critical of the reported mechanical advantages of the sliding capabilities provided by implants such as the sliding hip screw and the intramedullary hip screw. The benefit provided by the ability of these implants to achieve fracture impaction at the fracture site can be overcome by the disadvantage of excessive sliding leading to limb shortening and medial displacement of the distal fracture fragment. If fracture impaction is excessive there is a lack of fracture reduction. We also believe that failure to restore the normal hip anatomy is a substantial disadvantage for elderly hip fracture patients.

Regarding the absence of pin-track complications, we believe that this result can also be reproduced by other surgeons because it does not depend on the surgeon skill or familiarity with the technique but on the excellent osteointegrative ability of the coated pins. This is confirmed by the similar consistent results reported by all the authors who have published on HA-coated pins (2-5).

Finally, concerning the shorter operative time found in the external fixation group, we agree that it may reflect the skill of the surgeon in performing external fixation techniques, however, we believe that as the learning curve plateau is reached, even inexperienced orthopaedic surgeons can achieve similar results. The shorter operative time results from the minimally-invasive approach of this technique which features the straightforward implantation of two pins of small diameter into the femoral head. With OPF there is no need of additional surgical steps such as predrilling, sizing and tapping which are used in the majority of the SHS and IMHS fixation techniques to implant one or even two lag screws of significant diameter into the femoral head.

References:

1. A Moroni, C. Faldini, S. Marchetti, M. Manca, V. Consoli, S. Giannini Improvement of the Bone-pin Interface Strength in Osteoporotic Bone with Use of Hydroxyapatite-coated Tapered External-Fixation Pins: A prospective randomized clinical study of wrist fractures J Bone Joint Surg Am. 2001 May;83-A(5):717-21.

2. Piza G, Caja VL, Gonzalez-Viejo MA, Navarro A Hydroxyapatite- coated external fixation pins. The effect on pin loosening and pin-track infection in leg lengthening for short stature. J Bone Joint Surg Br. 2004 Aug;86(6):892-7.

3. Pommer A, Muhr G, David AHydroxyapatite-coated Schanz pins in external fixators used for distraction osteogenesis: a randomized, controlled trial. J Bone Joint Surg Am. 2002 Jul;84-A(7):1162-6.

4. Caja VL, Piza G, Navarro A Hydroxyapatite coating of external fixation pins to decrease axial deformity during tibial lengthening for short stature. J Bone Joint Surg Am. 2003 Aug;85-A(8): 1527-31.

5. Magyar G, Toksvig-Larsen S, Moroni A Hydroxyapatite coating of threaded pins enhances fixation. J Bone Joint Surg Br. 1997 May;79(3):487-9.

Dear Dr. Todkar,

Thank you for your interest and your questions about our article: “Dynamic Hip Screw compared with External Fixation for Treatment of Osteoporotic Pertrochanteric Fractures.”

As you may know, in fracture treatment, assessing the time required for fracture healing is not a simple task and this assessment can be based on different types of analyses. In our study, fracture healing was defined radiographically by the presence of trabeculae bridging the fracture site or obvious periosteal callus within the fracture line. Based on this definition, no differences in the time required for fracture healing were found between the two groups.

In a clinical setting, stability at the fracture site cannot be measured biomechanically. However, upon clinical evaluation at the time of surgery, no differences in fixation stability were found between OPF and DHS. Long-term results (6 months) showed better stability with the OPF as demonstrated by a lower loss of fracture reduction. This was measured by comparing the femoral neck shaft angle at 6 months with the femoral neck shaft angle at post-op.

In response to your question regarding the weight-bearing status, there were no weight-bearing restrictions in either group. Patients were encouraged to resume their full weight-bearing capacity as they recovered from surgery. In this study, the amount of load which was actually placed by the patient on the treated limb was not measured quantitatively in the post-operative period.

In all the patients, fixators were worn for three months as reported in the study.

Certainly, the fixator was a cause of some discomfort. However, it was well- tolerated by patients and did not significantly affect diurnal activities such as bed rest and sitting. It should also be said that at 5 days after surgery, there was a significantly higher level of pain in patients treated with DHS than in patients treated with OPF.

To the Editor:

I read the article " Dynamic Hip Screw Compared with External Fixation for Treatment of Osteoporotic Pertrochanteric Fractures. A Prospective, Randomized Study" with great interest. I congratulate the authors for trying to find a solution for these common fractures in osteoporotic bones, a situation that presents a real challenge for fixation with conventional implants.

I am interested in knowing whether the time required for healing of the fractures treated by external fixation was significantly different from the fractures fixed with sliding hip screw. What was the stability at fracture site achieved after fixation ? Were the fractures fixed with external fixators less stable than sliding hip screws ?

It would also be very interesting to know the weight bearing status after fixation in group B. As you know, partial or non weight bearing is very difficult in this age group of patients.

Addlitionally, could the authors please tell us how long the fixators were kept on the patients? How did the patients manage with the bulky fixators on one side? In our experience, it is difficult for patients to manage with fixators as they have problems woth clothing, turning in bed and using support while mobilising.

Yours sincerely,

MANOJ TODKAR