Session V - Geriatrics

Crush Syndrome after Proximal Femoral Fracture

Ashima Garg, MD; O. Quaba, MA; Carol Hajducka, RGN; Margaret M. McQueen, MD, Edinburgh Orthopaedic Trauma Unit, Edinburgh, Scotland

Purpose: To examine the effect of prolonged recumbency on the creatinine phosphokinase (CPK) levels, occurrence of crush syndrome and outcome after proximal femoral fracture.

Methods: Data for twenty-eight patients who were admitted with proximal femoral fractures to one orthopedic trauma unit during May 1995 were prospectively recorded. These patients had all been lying immobile for 6 hours or less after sustaining their fracture. Data were also collected for patients admitted with proximal femoral fractures who had been lying immobile for more than 6 hours. A total of 27 patients from May 1995 until October 1997 fulfilled these criteria.

The data collected included demographic details, type of hip fracture sustained (intertrochanteric or femoral neck), the length of time the patient was immobile and any other injuries sustained. Intercurrent illnesses were recorded in detail. Urea and electrolytes and CPK levels were recorded on admission and eight hours later. Any death occurring within 30 days of admission was noted. One patient who had an acute myocardial infarction was eliminated as the CPK would be falsely elevated and the effect of any rhabdomylosis masked.

There were 55 patients with an average age of 83.6 years and an age range of 68 to 94 years. There were 48 women and 7 men, with 33 intertrochanteric fractures and 22 subcapital fractures. The group who lay for six hours or less (Group 1) contained 2 men and 26 women with an average age of 84 years (range 61 to 95 years). The group who lay for more than six hours (Group 2) contained 3 men and 24 women with an average age of 84 years (range 68 to 93 years). The amount of time the patient was lying undetected with a fracture varied from a few minutes to six hours in the group 1 with an average of 1.7 hours and 7 to 120 hours in the group 2 with an average of 21.4 hours.

Crush syndrome was defined as more than five times the upper limit of normal for the CPK value.

Statistical analysis was performed using the Chi-squared test.

Results: For patients lying undetected for 6 hours or less, 6 of 28 patients (21.4%) had an elevated CPK. In the group which lay for more than 6 hours, 19 out of 27 patients (70.4%) had an elevated CPK on admission. This difference is statistically significant (p<0.001). One patient (3.6%) in group 1 had crush syndrome. Seven patients were admitted with crush syndrome (25.9%) in group 2. This difference is statistically significant (p<0.025).

Of the 55 patients, 6 died within one month of injury giving an overall mortality rate of 10.9%. On admission 25 patients had elevated CPK, and 5 of them died (20%). One patient of 30 with a normal CPK died (3.3%). There is a trend to a higher mortality rate in patients with an elevated CPK on admission (p=0.072). Four out of 9 patients (44.4%) with an established crush syndrome either on admission or eight hours later died. Only 2 patients of the remaining 46 (4.4%) died. If CPK was elevated on admission and continued to rise after 8 hours the mortality rate was 36% versus 7% if the CPK was declining.

Discussion: The effects of the crush syndrome are well recognised after prolonged recumbency after drug overdose, carbon monoxide poisoning and natural or man-made disasters. They are poorly recognised in elderly patients who have lain immobile for a long period of time after proximal femoral fracture. This study has demonstrated that crush syndrome occurs in the elderly patient in these circumstances and that elevated CPK levels are associated with prolonged recumbency in this group of patients. Elevated CPK levels on admission, rising CPK levels eight hours after admission and the presence of crush syndrome all lead to a higher mortality rate.

Conclusion: CPK levels should be measured in elderly patients who have lain immobile for more than six hours. Emergent treatment and renal support may aid in reducing mortality rates in patients in whom raised levels are detected.