Pydisetty RV, Madhusudan MG and Barnes KA

INTRODUCTION

Fracture of the femur is one of the most common injuries following high velocity trauma. These patients tend to sustain complicated fractures. To stabilise them most patients require internal fixation. Currently intramedullary nailing is used for stabilising the majority of femoral fractures. The normal leg is most commonly placed in hemi-lithotomy position during intramedullary nailing of the femur. In this position, the normal leg is supported with the hip and knee flexed and the leg abducted to allow access to the injured extremity for image intensifier viewing. Support is provided by a padded popliteal rest.

This study reports one patient who developed compartment syndrome in the normal leg following intramedullary nailing for a femoral fracture with the normal leg in the hemi-lithotomy position.

CASE REPORT

A 25-year-old man involved in a motorbike accident sustained closed communited fractures of the shaft of the femur and tibia. On arrival in causality, the patient was resuscitated according to ATLS guidelines and the limb was immobilised in a Thomas splint. The patient was taken to the operating theatre the following day with a view to stabilise the femur and tibia using intramedullary nailing. It was decided to fix the femoral fracture first and the patient was positioned on the fracture table with upper tibial pin traction. The fractured tibia was temporarily immobilised in a below knee back slab. The normal leg was placed in a leg holder, which consisted of a padded rest under the calf, supporting the hip and knee in a flexed position, and the hip abducted. The leg holder was well padded with Gamjee pads. Care was taken to ensure that there was no constriction at the popliteal fossa. Because of the complicated nature of the fracture, the procedure took six hrs. During that time, no specific attention was directed to the position, or condition of the uninvolved leg.

Because of the prolonged length of the procedure, nailing of the tibia was postponed until the following day. This patient was transferred to the High Dependency unit for overnight postoperative observation. During the night of the surgery, the patient complained of severe pain in the calf, parasthesia, and inability to move the toes and foot on the normal side. On examination, the leg was swollen and tender on palpation. There was diminished sensation on the dorsum and plantar aspect of foot. Passive stretching of the toes produced pain.

The patient was taken to theatre and fasciotomies were performed. All four compartments were released through two standard incisions. The musculature of the posterior compartment was found to be very swollen and failed to respond to stimulation. After adequate release, the incisions were left open. Sequential evaluation was performed in theatre in 48-hour intervals and the wounds were subsequently closed.

This patient was followed up in the clinic. The wounds healed well, the sensation and motor power improved. In November 2002, there was some residual numbness on the dorsum of the foot and grade 4 power in the muscles of the leg and foot. At the most recent review in February 2003 the patient regained full power and sensation of the foot and leg.

DISCUSSION

Compartment syndrome following hemi-lithomy positioning of the normal limb has been reported in eight cases in the orthopaedic literature. All these occurred during femoral nailing.

Leff et al2 in 1979 first described compartment syndrome resulting from the lithotomy position in a urology case. Nineteen cases have subsequently been reported in the surgical, anaesthetic and gynaecological literature. In all these reported cases the operating time ranged from five and a half to eleven and a half hours. In all these cases a wide range of devices were used to support the leg, ankle and foot. However, the implication is that positioning and support during a lengthy procedure could be the underlying cause of the postoperative compartment syndrome in the normal leg. In our case, the patient was put on a traction table and the normal leg was put in the hemi-lithotomy position with the hip and knee flexed with a well-padded support under the knee. This was done to facilitate the use of the 'C' arm for intra operative films.

Adler et al 1 described three patients with femoral fractures who developed compartment syndrome in the normal leg after intra medullary nailing in the hemi-lithotomy position. In each case, they used a "well padded leg holder". Operative times ranged from four and a half to seven hours. They suggested that patients with "greater limb weight may be predisposed to development of compartment syndrome". Tan et al 5 described monitoring compartment pressures in the normal leg of eight patients before, during, and after placement of the leg in the hemi-lithotomy position for femoral fracture nailing. They found a rapid increase in compartment pressures, from a mean of 9.2 to 27.3 millimetres of mercury, a continued increase in pressure while the leg remained in the holder, and an immediate return to near baseline levels once the leg was taken down. A positive correlation between body mass index and increased compartment pressures was found and indicated that obesity may be a contributing factor.

The pathophysiology of compartment syndrome in this scenario is unclear. The weight of the extremity may cause direct pressure on the vascular structures despite the presence of padding. The position of the leg itself may cause extrinsic compression of the vessels. These two factors could compromise the blood flow to the limb. In addition, elevation of the limb above the level of the heart has been shown to decrease arteriolar pressure by 0.78 mm Hg/cm above the atrium. In addition, intra operative hypotension occurring during general anaesthesia may further compromise blood flow3.

Meyers et al4 . state that increased intramuscular pressure due to external compression from the calf support, combined with decreased perfusion pressure due to the elevated position leads to a significant decrease in the difference between the diastolic pressure and the intramuscular pressure when the leg is placed in the hemi-lithotomy position in a well-leg holder on a fracture table.

In our patient the fracture, it took five and a half hours to achieve adequate fixation of his femoral fracture. This patient was a very well built man with a body mass index (BMI) of 32kg/m2 . These factors, combined with positioning, could explain the cause of the raised compartment pressures following operation. . In long procedures, frequent monitoring and repositioning of the normal limb will reduce the incidence of compartment syndrome. Adequate padding is necessary but may not be sufficient to prevent compartment syndrome. Leaving the calf free, with a heel-support decreases the intra-compartmental pressures by increasing the perfusion of muscles. This method of positioning may decrease the risk of acute compartment syndrome9.

In summary, the hemi-lithotomy position for the normal limb during femoral nailing with a fracture may be avoided and alternate positioning should be considered in order to reduce the risk of acute compartment syndrome.

CONCLUSIONS

Compartment syndrome is a serious and avoidable complication. When the risk factors are taken into account, this case shows that there is an argument for avoiding the hemi-lithotomy position of the normal leg in complicated cases where the operation time is likely to be prolonged.

REFERENCES

1. Adler LM, Heppenstall RB, Esterhai JL, Compartment syndrome in the well leg: a complication of the hemi-lithotomy position. Tech Orthop 1997; 12:133-135.

2. Leff RG, Shapiro SR. Lower extremity complications of the lithotomy position: prevention and management. J Urol 1979; 122: 138-139.

3. Matsen FA III. A practical approach to compartment syndromes. Part I. Definition, theory, and pathogenesis. Instr Course Lect 1983; 32: 88-92.

4. Meyers RS, White KK, Smith JM, Groppo ER, Mubarak SJ, Hargens AR. Intramuscular and blood pressures in legs positioned in the hemilithotomy position: clarification of risk factors for well-acute compartment syndrome. J Bone Joint Surg Am 2002; 84-A (10): 1829-35.

5. Tan V, Pepe MD, Glaser DL et al. Well-leg compartment pressures during hemi-lithotomy position for fracture fixation. J. Orthop Trauma 2000; 14: 157-161.