Dataset Information

Assessment of knee flexor muscles strength in patients with patellar instability and its clinical implications for the non-surgical treatment of patients after first patellar dislocation - pilot study.

ABSTRACT:

Background

Biomechanical studies indicate that during outward rotation of the tibia and the valgus knee joint position, the patella is shifted in the lateral direction. After first-time patellar dislocation, the dynamic position of the femur in relation to the tibia plays an important role in joint stability, because the medial stabilizer of the patella (mostly the MPFL) is damaged or inefficient. The most important factor in controlling the rotational movement of the tibia in relation to the thigh are the hamstring muscles. The aim of the study therefore is to determine whether patients with patellar instability have a significant weakness in the knee flexor muscles, which can predispose to recurrent dislocations. This is an important consideration when planning the rehabilitation of patients with first-time patellar dislocation.

Methods

The study enrolled 33 patients with confirmed recurrent patellar dislocation, including six patients with bilateral involvement. In the study group, the hamstring muscles (both sides) were evaluated at velocities of 60 and 180 deg/s for the following parameters: peak torque, torque at 30 degrees of knee flexion, angle of peak torque and peak torque hamstring to quadriceps ratio (H/Q ratio).

Results

In the recurrent patellar dislocation group, a statistically significant weakness in knee flexors was observed for both angular velocities compared to age and gender normative data. No such relationship was observed in the control group of heathy subjects. In patients with one-sided dislocation, no differences were found in knee flexors peak torque, torque at 30 degrees of knee flexion, angle of peak torque or H/Q ratio between the healthy and affected limbs for either angular velocity.

Conclusions

In patients with recurrent patellar dislocation, knee flexors strength is decreased significantly in both the unaffected and affected limbs. This may indicate a constitutional weakening of these muscles which can predispose to recurrent dislocations.

Trial registration

The study was retrospectively registered on ClinicalTrials.gov ( NCT04838158 ), date of registration; 22/03/2021.

SUBMITTER: Malecki K

PROVIDER: S-EPMC8403423 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:We examined the temporal changes of isokinetic strength performance of knee flexor (KF) and extensor (KE) strength after a football match. Players were randomly assigned to a control (N = 14, participated only in measurements and practices) or an experimental group (N = 20, participated also in a football match). Participants trained daily during the two days after the match. Match and training overload was monitored with GPS devices. Venous blood was sampled and muscle damage was assessed pre-match, post-match and at 12 h, 36 h and 60 h post-match. Isometric strength as well as eccentric and concentric peak torque of knee flexors and extensors in both limbs (dominant and non-dominant) were measured on an isokinetic dynamometer at baseline and at 12 h, 36 h and 60 h after the match. Functional (KFecc/KEcon) and conventional (KFcon/KEcon) ratios were then calculated. Only eccentric peak torque of knee flexors declined at 60 h after the match in the control group. In the experimental group: a) isometric strength of knee extensors and knee flexors declined (P<0.05) at 12 h (both limbs) and 36 h (dominant limb only), b) eccentric and concentric peak torque of knee extensors and flexors declined (P<0.05) in both limbs for 36 h at 60°/s and for 60 h at 180°/s with eccentric peak torque of knee flexors demonstrating a greater (P<0.05) reduction than concentric peak torque, c) strength deterioration was greater (P<0.05) at 180°/s and in dominant limb, d) the functional ratio was more sensitive to match-induced fatigue demonstrating a more prolonged decline. Discriminant and regression analysis revealed that strength deterioration and recovery may be related to the amount of eccentric actions performed during the match and athletes' football-specific conditioning. Our data suggest that recovery kinetics of knee flexor and extensor strength after a football match demonstrate strength, limb and velocity specificity and may depend on match physical overload and players' physical conditioning level.