Hip fracture is a major problem for elderly patients, with a significant cause of postfracture disability, morbidity and mortality, and is often associated with postoperative urinary retention, which can lead to renal insufficiency and extended stay in hospital. However, the aetiology of postoperative urinary retention of hip fracture is unclear because the autonomic nervous system which controlls urinary bladder function has no damage after hip fracture. Iliopsoas muscle, which is placed between the lumbar vertebra and lesser trochanter of femoral bone, has role in stabilizing the spine and maintaining the posture. Because abdominal muscle pressure and gravity with bladder detrusor muscle in seating or standing position have roles in effective urination when compared to in bed rest, iliopsoas muscle might have important role in voiding function. Thus, in this study, we examined the relation between the residual urine volume and iliopsoas muscle function after hip fracture.

A total of 148 patients with hip fracture were studied. Hip fracture was divided into 3 types; femoral neck fracture (n=96), trochanteric fracture with lesser trochanter injury (n=31), and trochanteric fracture without lesser trochanter injury (n=21). Urethral catheter was removed 2 or 3 days after hip surgery, and the postvoid residual urine volume was measured using ultrasonography for 24 hours after catheter removal. Intermittent catheterization (IC) was performed in patients with postvoid residual urine volume of over 200 ml. The ratio of IC was compared between femoral fracture vs. trochanteric fracture, and trochanteric fracture with lesser trochanter injury vs. without injury. Iliopsoas muscles mass was compared between before and after surgery using computerized tomography (n=8 in each group). In patients with trochanteric fracture with IC (n=6) or without IC (n=10), the fracture pattern of stable/unstable, the ability of holding of seating position, strength of iliopsoas muscles, and postoperative pain were assessed using Jensen classification, Hoffer classification, hand-held dynamometer, and numerical rating scale, respectively.

The ratio of IC for drainage of residual urine after surgery was significantly higher in trochanteric fracture (23%) compared to femoral fracture (10%), and was higher in trochanteric fracture with lesser trochanter injury (40%) than in patients without injury (20%). The iliopsoas muscle mass was significantly decreased in trochanteric fracture with lesser trochanter injury (-35%) compared to trochanteric fracture without lesser trochanter injury (-18%) and femoral fracture (-5%). Jensen classification revealed that unstable fracture pattern (type 3, 4 and 5) is larger (75%) in patients with IC compared to patients without IC (55%). The iliopsoas muscle strength was significantly weaker in patients with IC than in patients without IC. The recovery speed of the ability of holding of seating position assessed by Hoffer classification in patients with IC was slower than in patients without IC. There was no significant difference according to age, sex, and pain score between patients with and without IC.

This study suggests that (1) trochanteric fracture has relation with the increase of postvoid urine volume, (2) the iliopsoas muscle mass was significantly decreased in patients with lesser trochanter injury when compared to femoral fracture, and (3) the stability of fracture and the strength of iliopsoas muscle was significantly weaker and the recovery speed of the ability of holding of seating position was slower in patients with residual urine than in patients without residual urine. These results indicate that hip fracture with lesser trochanter injury induces the decrease of iliopsoas muscle function and the increase of postvoid residual urine. Because iliopsoas muscle has an important role for maintaining the posture during urination for effective voiding, the weak strength of iliopsoas muscle after trochanteric fracture might lead to urinary retention.

We need to attention on the iliopsoas muscle and the ability of maintaining posture during urination in elderly patients after hip fracture.