Ankle dorsiflexion in adolescent athletes

Passive Muscular Insufficiency: The Etiology of Gastrocnemius Equinus

The current understanding is that gastrocnemius equinus is caused by a pathologic tightening of the muscle leading to decreased ankle joint dorsiflexion. However, an alternative hypothesis is that it is a normal limitation of available muscle length. Passive muscular insufficiency of the gastrocnemius muscle acts on a pathologic foot, which is poorly prepared to accept the forces from the gastrocnemius-soleus complex. In this manner, a normal gastrocnemius muscle exerts abnormal forces across the foot. This alternative hypothesis leads to a different interpretation of the current research literature and a potential new area of biomechanical research.

The effect of the gastrocnemius on the plantar fascia

Although anatomic and functional relationship has been established between the gastrocnemius muscle, via the Achilles tendon, and the plantar fascia, the exact role of gastrocnemius tightness in foot and plantar fascia problems is not completely understood. This article summarizes past and current literature linking these 2 structures and gives a mechanical explanation based on functional models of the relationship between gastrocnemius tightness and plantar fascia. The effect of gastrocnemius tightness on the sagittal behavior of the foot is also discussed.

Sagittal plane kinematics of passive dorsiflexion of the foot in adolescent athletes

BACKGROUND

Although assessment of passive maximum foot dorsiflexion angle is performed routinely, there is a paucity of information regarding adolescents' foot and foot segment motion during this procedure. There are currently no trials investigating the kinematics of the adolescent foot during passive foot dorsiflexion.

METHODS

A six-camera optoelectronic motion capture system was used to collect kinematic data using the Oxford Foot Model. Eight female amateur gymnasts 11 to 16 years old (mean age, 13.2 years; mean height, 1.5 m) participated in the study. A dorsiflexing force was applied to the forefoot until reaching maximum resistance with the foot placed in the neutral, pronated, and supinated positions in random order. The maximum foot dorsiflexion angle and the range of movement of the forefoot to hindfoot, tibia to forefoot, and tibia to hindfoot angles were computed.

RESULTS

Mean ± SD maximum foot dorsiflexion angles were 36.3° ± 7.2° for pronated, 36.9° ± 4.0° for neutral, and 33.0° ± 4.9° for supinated postures. One-way repeated-measures analysis of variance results were nonsignificant among the 3 groups (P = .70), as were the forefoot to tibia angle and hindfoot to tibia angle variations (P = .091 and P = .188, respectively). Forefoot to hindfoot angle increased with the application of force, indicating that in adolescents, the forefoot does not lock at any particular posture as portrayed by the traditional Rootian paradigm.

CONCLUSIONS

Participants had very flexible foot dorsiflexion, unlike those in another study assessing adolescent athletes. This finding, together with nonsignificant statistical results, implies that foot dorsiflexion measurement may be performed at any foot posture without notably affecting results.

Validity and reliability of a new ankle dorsiflexion measurement device

BACKGROUND

The assessment of the maximum ankle dorsiflexion angle is an important clinical examination procedure. Evidence shows that the traditional goniometer is highly unreliable, and various designs of goniometers to measure the maximum ankle dorsiflexion angle rely on the application of a known force to obtain reliable results. Hence, an innovative ankle dorsiflexion measurement device was designed to make this measurement more reliable by holding the foot in a selected posture without the application of a known moment.

OBJECTIVES

To report on the comprehensive validity and reliability testing carried out on the new device.

METHODS

Following validity testing, four different trials to test reliability of the ankle dorsiflexion measurement device were performed. These trials included inter-rater and intra-rater testings with a controlled moment, intra-rater reliability testing with knees flexed and extended without a controlled moment, intra-rater testing with a patient population, and inter-rater reliability testing between four raters of varying experience without controlling moment. All raters were blinded.

STUDY DESIGN

A series of trials to test intra-rater and inter-rater reliabilities.

RESULTS

Intra-rater reliability intraclass correlation coefficient was 0.98 and inter-rater reliability intraclass correlation coefficient (2,1) was 0.953 with a controlled moment. With uncontrolled moment, very high reliability for intra-tester was also achieved (intraclass correlation coefficient = 0.94 with knees extended and intraclass correlation coefficient = 0.95 with knees flexed). For the trial investigating test-retest reliability with actual patients, intraclass correlation coefficient of 0.99 was obtained. In the trial investigating four different raters with uncontrolled moment, intraclass correlation coefficient of 0.91 was achieved.

CONCLUSIONS

The new ankle dorsiflexion measurement device is a valid and reliable device for measuring ankle dorsiflexion in both healthy subjects and patients, with both controlled and uncontrolled moments, even by multiple raters of varying experience when the foot is dorsiflexed to its end of range of motion.

CLINICAL RELEVANCE

An ankle dorsiflexion measuring device has been designed to increase the reliability of ankle dorsiflexion measurement and replace the traditional goniometer. While the majority of similar devices rely on application of a known moment to perform this measurement, it has been shown that this is not required with the new ankle dorsiflexion measurement device and, rather, foot posture should be taken into consideration as this affects the maximum ankle dorsiflexion angle.

Interrater and intrarater reliability in the measurement of ankle joint dorsiflexion is independent of examiner experience and technique used

BACKGROUND

Goniometric measurement is currently being used as a diagnostic and outcomes assessment tool for ankle joint dorsiflexion. Despite its common use, its interrater and intrarater reliability has been questioned.

METHODS

This is a prospective study examining whether the experience of the examiner or the technique used affects the interrater and intrarater reliability for measuring ankle joint dorsiflexion. Fourteen asymptomatic individuals (8 male and 6 female) with a mean age of 28.2 years (range, 23-52) were enrolled into this study. The years of clinical experience of the five examiners averaged 10.4 years (range, 0-26). Four examiners used a modified Root, Weed and Orien method of measuring ankle joint dorsiflexion. The fifth examiner utilized a nonstandardized technique. A standard goniometer was used for bilateral measurements of ankle joint dorsiflexion with the knee extended and flexed. All five examiners repeated each measurement three times during each of the three sessions, with each session spaced at least 1 week apart.

RESULTS

The interclass correlation coefficient reveals a moderate intrarater and poor interrater reliability in ankle joint dorsiflexion measurements using a standard goniometer. More importantly, further analysis indicates that the use of a standardized technique for measurement of ankle joint dorsiflexion or years of clinical experience does not increase the intrarater or interrater reliability.

CONCLUSIONS

The utility of the goniometric measurement of ankle joint dorsiflexion may be limited.

Endoscopic gastrocnemius recession for treating equinus in pediatric patients

Gastrocnemius recessions have been performed as open or endoscopic procedures. Most of the literature describes the outcomes of these procedures in children with specific neurologic limitations. We report an alternative approach to endoscopic gastrocnemius recessions in neurologically healthy pediatric and adolescent patients whose gastrocnemius equinus could not be corrected nonoperatively. We prospectively followed 23 patients (16 boys, seven girls) who underwent 40 procedures for equinus deformity (n = 22) or osteoarthritis (n = 1). All patients had been directly referred for surgical treatment because all previous nonoperative treatments (stretching, night splints, orthotics, nonsteroidal anti-inflammatory drugs, and physical therapy) had failed. The indications for surgery were patients age 18 years or younger experiencing symptomatic equinus unresponsive to nonoperative care. Pre- and postoperative ankle dorsiflexion were measured. The minimum followup for study inclusion was 1 year (mean, 2.9 years; range, 2-5.1 years). For every patient, dorsiflexion range of motion improved (mean, 15 degrees ; standard deviation, 4 degrees ). No patient had diminished nerve sensation postoperatively. This technique can be used to correct gastrocnemius equinus in otherwise healthy children who have not benefited from prior nonsurgical treatment.

LEVEL OF EVIDENCE

Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

The effect of triceps surae contracture force on plantar foot pressure distribution

BACKGROUND

Triceps surae contractures have been associated with foot and ankle pathology. Achilles tendon contractures have been shown to shift plantar foot pressure from the heel to the forefoot. The purpose of this study was to determine whether isolated gastrocnemius contractures had similar effects and to assess the effects of gastrocnemius or soleus contracture on midfoot plantar pressure.

METHODS

Ten fresh frozen cadaver below-knee specimens were loaded to 79 pounds (350 N) plantar force with the foot unconstrained on a 10-degree dorsiflexed plate. Combinations of static gastrocnemius or soleus forces were applied in 3-lb increments and plantar pressure recordings were obtained for the hindfoot, midfoot, and forefoot regions.

RESULTS

The percentage of plantar force borne by the forefoot and midfoot increased with triceps surae force, while that borne by the hindfoot decreased (p<or=0.005). Increasing gastrocnemius force had similar results. Increasing triceps surae force from 0 to 21 lbs (93 N) increased average percent forefoot and midfoot force 59% and 38%, respectively, and reduced average percent hindfoot force 18%. Increasing gastrocnemius force from 0 to 18 lbs increased average percent forefoot and midfoot force 50% and 32%, respectively, and reduced average percent hindfoot force 16%. For a given triceps surae force, there was no statistical difference in pressure distribution noted between different combinations of gastrocnemius and soleus force.

CONCLUSIONS

In a static model, increased triceps surae or isolated gastrocnemius force shifted weightbearing plantar pressure from the hindfoot to the midfoot and forefoot. Similar results were noted whether the triceps surae force was applied through the gastrocnemius or soleus or both. The results of this study are consistent with the clinical association of triceps surae contracture with foot and ankle disorders including diabetic foot ulcers and metatarsalgia. The similar effects with triceps surae force application through the gastrocnemius or soleus suggest that patients with isolated gastrocnemius contractures may obtain similar clinical benefits with potentially less morbidity after gastrocnemius aponeurosis lengthening as compared to Achilles tendon lengthening.