Annals of the Royal College of Surgeons of England (1990) vol. 72, 270-271

Rupture of the Achilles tendon: a new clinical test S A Copeland FRCS Consultant Orthopaedic Surgeon The Royal Berkshire Hospital, Reading

Key words: Achilles tendon; Tendon rupture; Test, clinical

A new diagnostic test using a sphygmomanometer cuff to detect a spontaneous rupture of the Achilles tendon is described. It has also been found to be useful in monitoring progress following treatment.

Spontaneous rupture of the Achilles tendon is still a clinical diagnosis that is frequently missed. Scheller et al. (1) showed that 25% of their patients were initially misdiagnosed due to the insignificance of presenting symptoms. Both patient and doctor can be misled by the patient's ability to maintain some degree of active plantar flexion in the presence of full tendon rupture. In the early stages, swelling and bruising may not be apparent. Later, swelling may cause difficulty in palpating a gap in the tendon. At that stage weakness of plantar flexion is attributed to pain rather than to complete tendon rupture. Simmonds (2) first described the 'calf squeeze' test. He noticed that if the calf muscles were squeezed in the normal patient, this produced a plantar flexion motion of the ankle. If the Achilles tendon was ruptured then the movement failed to occur. The same test was later described by Thompson and Doherty (3). O'Brien (4) described an ingenious needle test to distinguish the completely ruptured tendon. This test is reliable, but is invasive and can be painful. More recently, Fornage (5) and Laine (6) have found ultrasonography to be helpful in the differential diagnosis of Achilles tendon pain. Reinig (7) used nuclear magnetic resonance to display very clear images of the ruptured Achilles tendon. Both these tests are elegant and sophisticated, but also time consuming and unlikely to be of help in the acute

Method and results The patient lies face down on the examination couch. The knee is flexed to 900 and a sphygmomanometer cuff is applied around the bulk of the calf muscle. The cuff is inflated to approximately 100 mmHg with the ankle plantar flexed (Fig. 1). The ankle is then passively dorsiflexed by pressure on the sole of the foot (Fig. 2). If the Achilles tendon is intact, the column will be seen to rise to approximately 140 mmHg. If the tendon is disrupted, only a fficker of movement is seen in the Mercury column (Fig. 3). When the test was applied to 20 normal subjects, the variation of displacement of the Mercury column was between 35 and 60 mmHg. The test must be applied to both calves of the same individual to determine that particular patient's normal value. In the same 20 patients the variability of readings between the limbs was a maximum of 5 mmHg. The test was also applied to eight subjects following operative repair of the tendo Achilles and a period of 7 weeks' plaster immobilisation. The test could obviously not be applied during

situation.

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Correspondence to: Mr S A Copeland FRCS, Consultant Orthopaedic Surgeon, The Royal Berkshire Hospital, London Road, Reading, Berkshire

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Figure 1. The patient lies prone with the sphygmomanometer cuff applied to the calf, the foot in plantar flexion. Inflation pressure 100 mmHg.

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Rupture of the Achilles tendon

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the first 7 weeks. However, on removal of the plaster it was noted that the readings rose from the mean of 120 mmHg at 8 weeks to a mean of 135 mmHg at 40 weeks. One patient unfortunately had a late re-rupture at 11 weeks and his reading returned to only 10 mm of displacement indicating a partial re-rupture.

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Figure 2. The foot is passively dorsiflexed and the change in pressure noted.

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Discussion The absolute value of the rise in the Mercury column is not of significance when comparing patients, but is an extremely useful index of recovery in the individual. Following treatment the readings can be seen to rise over the ensuing weeks and months of recovery to equal that of the opposite leg. The test is thought to work because the cuff is basically a cylinder applied to a conical mass (the calf muscle). As the foot is dorsiflexed the cone is pulled down the cylinder displacing more air from the pneumatic cuff and hence increasing pressure and driving the Mercury column higher. The test has been found to be easy and simple to apply as the sphygmomanometer cuff is a readily available piece of medical equipment. It is found to be reliable and sensitive and is useful not only in the acute situation to determine whether the Achilles tendon is intact or not, but also as a quantitative guide in the individual patient to plot progress following treatment.

References I Scheller AD, Kasser JR, Quigley TB. Tendon injuries about the ankle. Orthop Clin North Am 1980;11:801-1 1. 2 Simmonds FA. The diagnosis of the ruptured Achilles tendon. Practitioner 1957;179:56-8. 3 Thompson TC, Doherty JH. Spontaneous rupture of tendon of Achilles; a new clinical diagnostic test. J Trauma 1962;2: 126-9. 4 O'Brien T. The needle test for complete rupture of the Achilles tendon. J Bone joint Surg 1984;66A: 1099-1101. S Fornage BD. Achilles tendon; ultrasound examination.

Radiology 1986;159(3):759-64. 6 Laine HR. Ultrasonography as a differential diagnostic aid in Achillodynia. J Ultrasound Med 1987;(6):351-62. 7 Reinig JW, Dorwart RH, Roden WC. Imaging of ruptured Achilles tendon. 7 Comput Assist Tomogr 1985;9(6):1131-4.

Figure 3. If the tendo Achilles is ruptured, pressure fails to rise on passive dorsiflexion.

Received 12 December 1989