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1,ury Vol. 27, No. 5, pp.355-356. 1996 Copyright (0 1996 Elsevier Science Ltd. All rights reserved

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Pure hyperextension of the knee causing popliteal artery injury

S. Jones and S. F. Journeaux Orthopaedic Department, Leeds General Infirmary, Great George Street, Leeds, UK

Injury, Vol. 27, No. 5, 355-356, 1996

Introduction

Popliteal artery injury is a recognized complication follow- ing a severe knee injuryl. Arterial injury following open knee injuries are usually obvious, as patients present with bleeding and hence are managed promptly by control of bleeding and vessel repair’. Closed knee injuries resulting in popliteal artery injury can be more difficult to recognize and delayed treatment results in amputation in up to 40 per cent of cases2-5.

In this article we discuss the case of a patient who sustained a complete popliteal artery avulsion following extreme hyperextension of his knee whilst playing rugby.

Case report

A Jo-year-old man was admitted to hospital with an injury of his left knee sustained whilst playing Rugby Union football. The mechanism of injury was that his foot became stuck in the mud with his left knee fully extended. An opposition player tackled him from the front imparting a direct blow to the front of his tibia which caused abnormal hyperextension of the knee.

On assessment in the Accident and Emergency department he had a painful left knee, and paraesthesia of the left leg distal to the knee. His left knee demonstrated gross diffuse swelling both anteriorly and posteriorly. He had a cool and dusky left foot with delayed capillary refill. There was no palpable left ankle or foot pulses and he had decreased sensation to pin prick over most of the left foot. Plain X-rays of his left knee showed no evidence of a dislocation or fracture.

He was taken to the operating theatre within 3 h of the injury and under anaesthesia his left knee was examined, his left popliteal fossa explored for presumed arterial injury and com- partment pressures, were measured. This examination showed anterior/posterior laxity although this was difficult to ascertain because of swelling, but interestingly he had no varus/valgus laxity.

His left popliteal artery was found to be completely avulsed at the trifurcation. This was repaired with an interposed reversed vein graft taken from his right leg. It was noted at operation that he had a rupture of the posterior capsule and cruciate ligaments of the left knee.

Compartment pressures were abnormal and in addition because of the vascular injury he had a four-compartment

fasciotomy of his left leg. No attempt was made to reconstruct his cruciate ligaments. Immediately after the operation he had a well-perfused left leg with palpable pedal pulses.

Two days after the operation he underwent a re-exploration of his left popliteal fossa for presumed graft thrombosis and a large arterial thrombus was removed. Thrombectomy restored good distal circulation.

The fasciotomy incisions were closed 4 days after the operation and he required a skin graft to the popliteal wound.

He was discharged home after 1 week in a full above-knee plaster cast. At subsequent outpatient review he was mobilized in a cast-brace once wound healing was complete and was left free of the cast at 8 weeks. At the last outpatient review (3 months after the injury) he had good distal pulses and a stable knee on varus/valgus testing. Anterior/posterior laxity was minimal on clinical testing although the patient has not mobil- ized fully independently to assess functional instability.

Discussion

Dislocation of the knee and severe associated ligament injuries are one of the most serious injuries of the lower limbs”. Mostly the injuries result from sporting events or road traffic accidents, with the mechanism of injury being one of severe direct or indirect force7.

In our patient the cause was a direct blow to the knee whilst playing rugby resulting in a pure hyperextension injury with rupture of the posterior capsule and cruciate ligaments. The popliteal artery is relatively fixed in position behind the knee by the geniculate vessels and the ligamentous structures of the popliteal fossa and any severe force applied to the knee results in shearing or avulsion of the popliteal artery’. Pure hyperextension of the knee with a popliteal artery avulsion does not appear to have been recorded in the literature before.

In 1963 Kennedy using a stress machine and cadaver knees demonstrated that at 50” of hyperextension the popliteal artery could rupture9. This would account for the injury of the popiteal artery in our patient.

Popliteal artery injuries are now always apparent in severe knee injuries. Varnell et al.“’ have found no significant difference in the frequency of arterial injuries with knee dislocation or those occurring with ligament rupture alone. Hence in all these injuries a high index of suspicion should be maintained at all times’. The diagnosis of a vascular injury is a clinical one”; hence the importance of an accurate history and thorough physical examination.

356 Injury: International Journal of the Care of the Injured Vol. 27, No. 5, 1996

Physical examination should include assessment of pulses, motor and sensory function and they must be reassessed on a regular basis and recorded”.

There is a requirement for an imaging technique capable of assessing internal derangement of the knee accurately and noninvasively’3. Magnetic resonance imaging (MRI) has emerged as the technique of choice as, unlike ultra- sonography, it is not operator dependent. MRI is per- formed to confirm suspected abnormalities of tendons and ligaments prior to surgery or those which are not amenable to surgical treatment13. The role of angiography remains controversial’z and has been adopted in selected cases. It is not indicated in obviously ischaemic limbs’“. Miller has shown that the critical period for successful arterial repair is an ischaemic interval of 6-8 h in experiments on dogs in 1949~~. Various clinical reviews have shown that this is applicable to humans5,‘5. There is a danger in exceeding this critical period and prolonging ischaemia in trying to procure an anteriogram, before popliteal exploration.

Limb salvage after revascularization has been shown to decrease from 90 per cent at 6 h to less than 50 per cent at 12 to 18 hlz. Vascular exploration and repair with a reversed saphenous vein graft is almost always necessary because of the extensive initimal and adventitial damage incurred6.

A four-compartment fasciotomy is also necessary, par- ticularly following blunt injuries, for two reasons: acute comparment syndrome after contusion, haemorrhage, or fractures’; and obligate reactive oedema in calf compart- ments after vascular reconstruction5. The decision to do this should always be made at the time of vascular explorations.

These patients require long-term follow up to access/ evaluate graft patency. Duplex ultrasound scans may have a role to play in assessing graft patencylz.

References

I Jones RE, Smith EC and Bone GE. Vascular and orthopaedic complications of knee dislocation. Stirg GynaecoI Obstet 1979; 149: 554.

2 Alberty RE, Goodfred G and Boydes AM. Popliteal artery injury with fracture dislocation of the knee. Am ] Surg 1981; 142: 36.

3 Synder WH, Watkins WL and Boe GE. Civilian popliteal artery trauma. An eleven year experience with 83 injuries. Surgery 1979; 85: 101.

4 Lefrak EA. Knee dislocation. Arch Surg 1976; 111: 1021. 5 Conkle DM, Richie RE et al. Surgical treatment of popliteal

artery injuries. Arch Strrg 1975; 110: 1357. 6 Frassica FJ, Sim FH, Staehelli JW, Pairolero PC. Dislocation of

the knee. C/in Orthop Rel Res 1991; 236: 200. 7 Aylesbury AR, Arden GP and Rainey HA. Traumatic

dislocation of the knee. J Bone Joint Surg 1972; 54: 96. 8 MacNeil JW and McGee GS. Popliteal artery injury in the

lumberjack. South A4ed ] 1994; 87: 958. 9 Kennedy TC. Complete dislocation of the knee joint. ] Bone

joint Surg [Am] 1963; 45.k 889. 10 Varnell RM, Coldwell DM, Sangorean BJ et al. Arterial injury

complicating knee disruption. Am Surg 1988; 55: 699.‘

11 Rose SC, Moore EE. Trauma angiography. The use of clinical findings to improve patient selection and case presentation. ] Trauma 1988; 28: 240.

12 Kendall RN, Taylor DC, Salvia AJ and O’Brien PJ. The role of arteriography in assessing vascular injuries associated with dislocation of the knee. ] Trauma 1993; 35: 875.

13 Heron CW. Review article: MRI of the knee. Br J Radio1 1993; 66: 292.

14 Miller HH, Wech CS. Quantitative studies on the factor in arterial injuries. Am Surg 1949; 130: 538.

15 Snyder WH. Vascular injuries near the knee. An updated series and review of the problem. Surgery 1982; 91: 502.

Paper accepted 18 January 1996.

Requests for reprints should be addressed to: Mr S. Jones, Orthopae- die Department, Leeds General Infirmary, Great George Street, Leeds LSl 3EX. UK.