Altered Gastrocnemius Contractile Behavior in Former Achilles Tendon Rupture Patients During Walking

Abstract

Achilles tendon rupture (ATR) remains associated with functional limitations years after injury. Architectural remodeling of the gastrocnemius medialis (GM) muscle is typically observed in the affected leg and may compensate force deficits caused by a longer tendon. Yet patients seem to retain functional limitations during—low-force—walking gait. To explore the potential limits imposed by the remodeled GM muscle-tendon unit (MTU) on walking gait, we examined the contractile behavior of muscle fascicles during the stance phase. In a cross-sectional design, we studied nine former patients (males; age: 45 ± 9 years; height: 180 ± 7 cm; weight: 83 ± 6 kg) with a history of complete unilateral ATR, approximately 4 years post-surgery. Using ultrasonography, GM tendon morphology, muscle architecture at rest, and fascicular behavior were assessed during walking at 1.5 m⋅s–1 on a treadmill. Walking patterns were recorded with a motion capture system. The unaffected leg served as control. Lower limbs kinematics were largely similar between legs during walking. Typical features of ATR-related MTU remodeling were observed during the stance sub-phases corresponding to series elastic element (SEE) lengthening (energy storage) and SEE shortening (energy release), with shorter GM fascicles (36 and 36%, respectively) and greater pennation angles (8° and 12°, respectively). However, relative to the optimal fascicle length for force production, fascicles operated at comparable length in both legs. Similarly, when expressed relative to optimal fascicle length, fascicle contraction velocity was not different between sides, except at the time-point of peak series elastic element (SEE) length, where it was 39 ± 49% lower in the affected leg. Concomitantly, fascicles rotation during contraction was greater in the affected leg during the whole stance-phase, and architectural gear ratios (AGR) was larger during SEE lengthening. Under the present testing conditions, former ATR patients had recovered a relatively symmetrical walking gait pattern. Differences in seen AGR seem to accommodate the profound changes in MTU architecture, limiting the required fascicle shortening velocity. Overall, the contractile behavior of the GM fascicles does not restrict length- or velocity-dependent force potentials during this locomotor task.

Supervised Physiotherapy Improves Three-Dimensional (3D) Gait Parameters in Patients after Surgical Suturing of the Achilles Tendon Using an Open Method (SSATOM)

“…The literature analysis indicates that some of the authors presented a biomechanical assessment of gait in patients treated conservatively [ 22 , 26 , 40 , 41 , 42 ] and surgically [ 21 , 27 , 43 ] after AT rupture. Moreover, studies indicate that the authors used various methods and surgical techniques [ 44 , 45 , 46 ].…”

“…Different physiotherapy protocols and the level of accuracy of the description of these protocols, as well as the duration of physiotherapy, are known [ 11 , 16 , 28 ]. Some publications do not contain a description of physiotherapeutic procedures or are limited to providing basic schemas of early postoperative management [ 15 , 22 , 43 ].…”

Movement in low gravity environments (MoLo) programme–The MoLo-L.O.O.P. study protocol

“…Real-time B-mode ultrasound using a linear array transducer placed in a custom-made cast and secured with elastic bandages will be positioned over both the m. gastrocnemius medialis mid-belly to determine fascicle length and pennation angles [ 28 , 53 ], and over the myotendinous junction (MTJ) to determine tendon length [ 54 , 55 ]. The ultrasound recordings will be time-synchronized with the other data acquisition systems through a TTL pulse passed through the auxiliary ECG channel.…”

“…For the determination of tendon length, three markers are attached to the ultrasound transducer, enabling the transformation of the tracked fascicle insertion point close to the MTJ in the 2D ultrasound image into the global reference system. Additionally, the m. gastrocnemius medialis tendon length, fascicle length and pennation angle are determined while subjects are lying prone with the knee and ankle joints in anatomically neutral positions (knee fully extended, sole perpendicular to the tibia) and muscles are relaxed [ 53 ].…”