Effect of Q-angle, Lateral Distal Tibial Angle and Proximal Muscle Torque on Ankle Injury

Ankle sprain is the most common type of ankle injury, comprising nearly 80% of all injuries affecting this area. Among these, 77% consists of sprains involving the lateral ankle (1). In sedentary individuals, the reported incidence is 5.2 to 6 per 1000 persons (2). Although the reported risk factors for ankle sprain include asymmetric tension in the flexor muscles of the ankle, increased body mass index (BMI), increased bodyweight, and younger age, definitive data is lacking (2).

The alignment of the pelvis, knee, and ankle has attracted significant research interest as a potential risk factor for lower extremity injury. Also, the quadriceps angle (Q angle) was reported to be an indicator for the biomechanical functions of the lower extremity, reflecting the effect of the quadriceps mechanisms on the knee, as well as providing information on patellar movements within the trochlear sulcus and on the functions of the thigh muscles (3). Q angle is measured as the narrow angle between the line that connects the anterior superior iliac spine (ASIS) to mid-patella and the line that connects the tibial tubercle with the center of patella (3, 4). Currently, no consensus exists regarding the normal value of the Q angle. While the American Orthopedics Society considers 10 degrees normal and 15 to 20 degrees as pathologic, the normal values reported by Schulthies et al. for males and females are 10 to 14 degrees, and 14.5 to 17 degrees, respectively (5). Several studies suggested that Q angle may actually represent an independent risk factor associated with increased risk of ankle sprain (4, 5). It has been proposed that individuals with knee valgus and a Q value exceeding 15 degrees have an increased risk of lower extremity injury. Also, a positive correlation between ankle sprain and Q angle was reported among recreational basketball players (3). On the other hand, no direct correlations were found between these two parameters in a study involving 45 professional athletes (4).

Another parameter that can be utilized to evaluate the alignment disorders of the lower extremity is the lateral distal tibial angle (LTDA). The average angle between the distal tibial joint orientation line and the anatomical and mechanical axis of the tibia is 89 degrees. This angle is referred to as LDTA (Figure 1). An angle of less than 86 degrees and more than 92 degrees indicate the presence of valgus and varus deformities, respectively (6). To the best of our knowledge, no previous studies have examined the association between LDTA and ankle sprain. It is plausible to assume that pathological LDTA, which is one of the alignment parameters of the lower extremity, may increase the predisposition to varus or valgus sprains. Therefore, our study was based on the hypothesis that LDTA may have an effect on the occurrence of ankle sprain, and thus it represents an intriguing research parameter. Also, when proximal muscle strength is assessed in people with chronic ankle imbalance, lack of muscle strength may be another potential risk factor for injury risk (9). This latter was particularly evident in studies that showed that the abductor muscle defects may lead to poor balance and neuromuscular adaptations in the ankle, therefore, contributing to increased inversion moments, increased activation, and earlier activation of the ankle evertors. When compared with athletes without injury, those with injury had weaker pelvic abduction and pelvic external rotation strength. In contrast, a prospective study by McHugh and colleagues concluded that the pelvic abductor, flexor or adductor strength had no role in predicting the future risk of ankle sprain (10).

Therefore, the published literature on the potential effects of Q angle on ankle sprain is controversial. On the other hand, literature data on the role of LDTA and proximal muscle strength on injury risk is also far from being clear. The primary objective of our study was to examine whether Q angle, LDTA, and knee and pelvic muscular torque were associated with ankle sprain. The secondary objective was to determine the parameter that had the most prominent impact on ankle injury risk.