CASE REPORTS

The first patient (case 1), a 28 year old female recreational runner (height 1.7 m, weight 60 kg), was a self referral to the University of Teesside Sport and Exercise Injury Clinic with bilateral lower leg pain. She exercised three times a week (4 miles on two occasions and 6 miles on the third). Before each run, she followed a standard warm up protocol. The patient was in good health with no history of trauma or illness, except for lower leg pain, particularly on the left side. Pain had gradually increased over the preceding four months, and at the time of reporting to the clinic started after 10 minutes of activity. The insidious pain always caused her to cease running. On the advice of her general practitioner, she had stopped running completely for three weeks, but pain reoccurred immediately after returning to activity.

The second patient (case 2), a 20 year old male club sprinter, was referred to our clinic by a local consultant orthopaedic surgeon at Hartlepool General Hospital (Hartlepool, UK). The patient had been experiencing symptoms in both legs, particularly the right. The clinical diagnosis offered was “probably anterior compartment syndrome.” At the time of referral, the patient was inactive and on the waiting list for fasciotomy.

Lower leg pain is the most common cause of disabling leg pain in young competitive athletes.¹ Chronic exertional compartment syndrome (CECS), the most common form of such pain, is an overuse injury, which manifests itself in the form of pain in the anterior compartment during activity.^2–5 Ideally, the diagnosis of compartment syndrome is made on the basis of pressure measurement.^6,7

However, there is no doubt that the clinical history of both patients suggested CECS. The patients presented with aching pain and tightness in the lower leg on exercise.⁸ Pain required the patient to interrupt their running, again implicating CECS.² The pain was fully relieved by rest.⁹

Although we cannot present an incontrovertible diagnosis of CECS, both patients displayed severe pain on running causing them to stop. We would have preferred to perform intracompartmental pressure testing to confirm our clinical history and examination but ready access is difficult for a small sports injury clinic such as ours.

However, in the absence of such equipment, the diagnosis must be made by a process of exclusion.⁸ Lower extremity alignment apparent and actual lower leg lengths, ranges of motion, patella position, and mobility were all considered normal. In case 1, a score of 74/80 was recorded on the lower extremity functional scale.¹⁰ Bilateral peak torque muscle strength of the dorsiflexors and plantarflexors was assessed. Peak torque assessments were used, as it has been shown that the data generated are subject to the least measurement error.¹¹ The isokinetic testing procedure followed the method suggested by Gajdosik.¹² The patient was placed in a supine position with the knee extended and the ankle joint aligned with the actuator of the cybex. The angular velocity of 120°/s used is normally regarded as a medium speed for testing of the ankle.¹³ The peak torque ratio (%) between right and left foot plantarflexion and dorsiflexion strength was calculated, enabling us to compare the relative strength of the dorsiflexors and plantarflexors. The ratio of dorsiflexor torque to plantarflexor torque was 80% (right side) and 120% (left side) in case 1. The value of 120% showed that the dorsiflexors on the more painful left leg produced a greater peak torque than the plantarflexors, the reverse of the result for the less painful right leg. These values were considered high compared with the 30–40% expected for the normal population.¹⁴

A video assessment of gait was undertaken on both patients.¹⁵ Their walking gait appeared to be normal over a range of speeds (2–5 km/h). The patients were then asked to run on a powered treadmill at their usual running speed (7.8 km/h in case 1 and 17 km/h in case 2) on two separate occasions. Examinations took place directly after activity.^2,16 During the first sessions the athletes ran in their normal running shoes. On the second occasion, they ran unshod. Although movements in both frontal and sagittal planes were captured, the sagittal view revealed more substantial differences between shod and unshod running. In both cases, there was heel strike, but there was a noticeable difference in the ankle position at the instant of impact. During shod running, the foot landed in a more dorsiflexed position than during unshod running. Such a difference has been attributed as an adaptive response to improve shock absorption for bare footed running in the absence of external cushioning.¹⁷ More surprisingly, however, were the results of the completed pain scale questionnaires. It is noteworthy that the unshod running, although causing slight superficial pain to the sole of the foot, was almost pain-free in the anterior compartment—the region of interest. In contrast, the shod running resulted in a reoccurrence of the described symptoms.

REHABILITATION PROGRAMME

Three days later the exercises were repeated. Despite the unshod running causing less pain, this type of running was deemed inappropriate given the normal terrain covered during the patients’ training routines. Thus, in an attempt to reproduce the unshod running style but for an outside environment, the subjects were asked to repeat the protocol but this time wearing footwear with harder, thinner soles. A sports therapist accompanied the patients on a 30 minute run outside on concrete terrain. Pain was monitored verbally during the run, and an analogue visual graphic pain rating score was completed after the run.¹⁸ Again, as with the unshod running, “no pain” scores were recorded throughout. A progressive five week training programme using these harder and thinner soled trainers was administered (case 1). Training began with 25 minutes running per session. This was increased by two minutes for each subsequent session. The patient was advised to take one day’s rest between sessions. The second patient was advised to return immediately to normal training wearing the harder, thin soled shoes. Since visiting the clinic 48 (case 1) and eight (case 2) weeks ago, both patients have returned to a pain-free full training schedule.

DISCUSSION

To understand the success of our intervention strategy, it is first appropriate to explain clinically what is believed to have been the underlying cause of this lower leg pain. In doing so, we acknowledge that the facilities in our clinic do not at present allow definitive diagnosis, but, on the basis of the evidence presented, both patients were suffering pain in the lower leg as a result of pressure build up within the anterior compartment, thus reducing venous drainage.¹⁹ As muscle activity is the primary cause of this pressure, it is likely to have fundamental importance in causing pain. Thus reducing muscle activity within the anterior compartment was the solution sought. The tibialis anterior, the largest of these dorsiflexing muscles, has been shown to undergo a burst of activity just after heel strike.^15,20 This activity is eccentric and is the dynamic response required to stabilise the ankle against a large plantar flexing moment (>20 N.m), thus preventing the foot slapping on the ground.²⁰ When the runner was unshod or in the hard, thin soled shoes, the ankle was positioned in a less dorsiflexed position at the point of impact. As the angle through which the ankle had to travel in order to reach mid-foot contact was reduced, it is suggested that dorsiflexor activity was reduced. Although more sophisticated equipment would be required to substantiate these claims, it has recently been shown that muscle activity can be influenced by the amount of cushioning of the shoe.²¹ In so doing, it is likely that the activity is reduced, which in turn would explain the zero pain scores.

Despite our two successes, the findings of this study must be treated with caution. Firstly, we suspect that the diagnosis in our patients was anterior compartment syndrome, but, without the use of pressure measurements, we cannot confirm the diagnosis. Secondly, the claimed success of this strategy is based on a sample size of two. Consequently, the statistical strength for making inferences with regard to the general population is not very strong. Thirdly, the explanation for the success is only based on basic laws of biomechanics. More sophisticated musculoskeletal models would be required to substantiate any claims of reduced dorsiflexor activity while running unshod or in hard, thin soled trainers. Regardless of these limitations, however, the fact remains that these two patients presented to our clinic with lower leg pain and left with zero pain. Given such successes and also that this intervention is both ethical and cheap, we suggest that this strategy has the potential for managing lower leg pain in a primary care setting. Furthermore, given that the results are more or less instantaneous, if it is not successful, then a more traditional solution can be sought without causing unnecessary delay.