Patellar Tendon Force Differs Depending on Jump-Landing Tasks and Estimation Methods

Patellar tendinopathy is a chronic overuse injury of the patellar tendon which is prevalent in jump-landing activities. Sports activities can require jumping not only with a vertical component but also in a forward direction. It is yet unknown how jumping in the forward direction may affect patellar tendon forces. The main purpose of this study was to compare PTF between landings preceded by a vertical jump and a forward jump in volleyball players. The second purpose was to compare two different estimation methods of the patellar tendon force. Fifteen male volleyball players performed vertical and forward jump-landing tasks at a controlled jump height, while kinetics and kinematics were recorded. Patellar tendon forces were calculated through two estimation methods based on inverse dynamic and static optimization procedures, using a musculoskeletal model. Results showed that forward jump-landing generated higher patellar tendon forces compared to vertical jump-landing for both estimation methods. Surprisingly, although the static optimization method considered muscle co-contraction, the inverse kinematic method provided statistically significant higher patellar tendon force values. These findings highlight that limiting the forward velocity component of the aerial phase appears to reduce the load on the patellar tendon during landing and may help to prevent patellar tendinopathy.

Arthroscopic Patellar Tendon Debridement and Distal Pole Osteoplasty for Recalcitrant Patellar Tendinopathy

Background: Chronic patellar tendinosis is an overuse injury of the patellar tendon that commonly afflicts jumping athletes. Indications: For patients with refractory symptoms that do not respond to extensive physical therapy and rest, surgical management may be considered. Although both open and arthroscopic treatments have been described, arthroscopic treatment allows for more direct access to the diseased dorsal portion of the tendon and allows for faster return to activities and sport. Technique Description: Arthroscopic treatment involves debridement of the diseased portion of the patella tendon and osteoplasty of the distal pole of the patella. The infrapatellar fat pad is first debrided using an arthroscopic shaver and radiofrequency ablation device to the level of the dorsal surface of the patellar tendon. Under direct arthroscopic visualization and corresponding to the location of edema noted on the magnetic resonance image, the diseased portion of the patellar tendon is gently debrided with an arthroscopic shaver. Next, an osteoplasty of the distal pole of the patella is performed to facilitate bleeding and healing of the diseased tendon as well as eliminate any mechanical impingement. Any calcifications within the enthesis can be removed using an arthroscopic biter and resector. An arthroscopic resector is then used to decorticate and smoothen the distal pole of the patella to the level of healthy, bleeding cancellous bone. Results: Significant improvements in pain and function have been reported with arthroscopic treatment for chronic patellar tendinosis. Patients can expect a 90% return to sport rate following the procedure, with return to preinjury function as soon as 3 to 5 months. This procedure is well tolerated with minimal complications reported. Discussion: Arthroscopic patellar tendon debridement and distal pole osteoplasty can be used to treat chronic patellar tendinosis refractory to nonoperative treatment. Improvements in pain and function have been reported with this technique, along with a faster return to sport compared with traditional open techniques.

Association of Ankle Dorsiflexion and Landing Forces in Jumping Athletes

Background: Dorsiflexion range of motion restriction has been associated with patellar tendinopathy, but the mechanisms of how dorsiflexion restriction could contribute to knee overload remain unknown. Hypothesis: Peak ankle dorsiflexion and ankle dorsiflexion excursion are negatively associated with peak vertical ground-reaction force (vGRF) and loading rate, and with peak patellar tendon force and loading rate, and positively associated with peak ankle plantar flexor moment. Study Design: Cross-sectional study. Level of Evidence: Level 4. Methods: Kinematic and kinetic data of 26 healthy recreational jumping athletes were measured during a single-leg drop vertical jump. Pearson’s correlation coefficients were calculated to establish the association between peak ankle dorsiflexion and ankle dorsiflexion excursion with peak vGRF and vGRF loading rate, with peak patellar tendon force and patellar tendon force loading rate, and with peak ankle plantar flexor moment. Results: Ankle dorsiflexion excursion negatively correlated with peak vGRF loading rate ( r = −0.49; P = 0.011) and positively correlated with peak ankle flexor plantar moment ( r = 0.52; P = 0.006). In addition, there was a positive correlation between peak ankle dorsiflexion and peak vGRF ( r = 0.39; P = 0.05). Conclusion: Ankle kinematics are associated with vGRF loading rate, ankle flexor plantar moment and peak vGRF influencing knee loads, but no association was observed between ankle kinematics and patellar tendon loads. Clinical Relevance: These results suggest that increasing ankle dorsiflexion excursion may be an important strategy to reduce lower limb loads during landings but should not be viewed as the main factor for reducing patellar tendon force.