From Limb Loss to Bone Loss

Presentation Number: SUN 312
Date of Presentation: April 2nd, 2017

Sheliza Lalani*1, Eric S Nylen2 and Shruti Mahendra Gandhi3
1George Washington University, Washington, DC, 2Veterans Affairs Medical Center, Washington, DC, 3Washington DC VA Medical Center, DC

Abstract

Introduction

Osteoporosis is a silent disease with many known risk factors including circumstances including immobilization and unloading (e.g., space travel and scuba diving)1. Following lower extremity amputation, bone turnover rates become discordant between the amputated and intact limb with some reports documenting increased fracture2,3. Since the current guidelines for osteoporosis (i.e., National Osteoporosis Foundation, Endocrine Society, American Association of Clinical Endocrinologists) or prospective DEXA programs such as NHANES do not include amputation as a factor for accelerated bone loss, we undertook this exploratory chart review in a population of veteran subjects with a high prevalence of limb amputation.

Method

Veterans with lower extremity amputations based on ICD-9/10 coding were cross-referenced with DEXA reports at the Washington DC VA Medical Center.

Results

Out of 571 amputees, 33 patients had received a screening DEXA after amputation (6%). We excluded patients with bilateral lower extremity amputations or a history of CVA with paralysis. The remaining 13 male veterans had an average post-amputation duration (time from amputation to DEXA) of 11 years. The differences in bone mineral densities (BMD) of the total femoral neck on the amputated side were compared to the non-amputated side (reference) for each patient. The BMD values were significantly lower on the side of the amputation with a mean difference of 0.268 g/cm2 (p=0.0015). A total of 6 patients (48%) were found to have osteoporosis on the amputated side (T score range -2.9 to -5). Only 1 of the 6 patients with osteoporosis had bilateral disease and just 3 received treatment with a bisphosphonate. An additional 6 patients had osteopenia. Lastly, the post-amputation duration was directly correlated with differences in BMD (r2=0.16; p=0.015).

Conclusion

This study confirms that there is accelerated bone loss ipsilateral to the amputation which is aggravated by the time post-surgery. Moreover, there was a paucity of recognition of the negative impact that amputations have on skeletal health despite the availability of effective screening with DEXA. A review of the literature demonstrates a limited number of relevant studies1-4. There appears to be an increased risk of hip fracture on the side of the amputation which may be secondary to a decline in BMD or in combination with higher rates of falls. Interestingly, the decline in BMD occurs despite prosthesis use, suggesting additional mechanisms such as an altered load at the amputated side or increased bone turnover at those sites1. While more data is clearly desirable, it is important for clinicians to recognize that patients with amputations have a higher risk of bone loss at the hip and should be screened early to assess their bone health with the ultimate goal of fracture prevention.

 

Nothing to Disclose: SL, ESN, SMG