The rehabilitation of knee injuries involving the anterior cruciate ligament (ACL) is controversial. This paper describes strain in the normal and reconstructed ACL during a series of passive and active tests of knee flexion with and without varus, valgus, and axial rotation torques on the tibia. Strain in the human knee ACL was significantly different depending on whether the knee flexion angle was changed passively or via simulated quadriceps contraction. The knee joint capsule was found to be important for strain protection of the ACL. Quadriceps activity did not strain the normal or reconstructed ACL when the knee was flexed beyond 60 degrees, but significantly strained the tissue from 0 to 45 degrees of knee flexion. Immobilization may not protect the ACL if isometric quadriceps contractions are allowed to occur. Properly placed reconstructions exhibited strain behavior which closely followed the anteromedial band of the ACL.

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Background: Treatment for displaced proximal humeral fractures is still under debate. Poor rota-tor cuff status and non-union of the tubercles in elderly patients has caused reversed total shoulder prosthesis growing popularity and showed promising results, even in comparison to angular stable plates fixation. The purpose of this study is to report clinical and radiological results of proximal humerus fractures treated with rTSA or ORIF in elderly. Materials and methods: The study has investigated retrospectively a consecutive series of 73 patients over 65 years old (range 65-91) with proxi-mal humeral three-and four-parts fractures, operated from January 2009 to June 2014 with a reversed total shoulder prosthetic replacement or open reduction and internal fixation using an angular stable plate, with at least 1 year follow-up. Participants are admitted in our hospital with a displaced proximal humeral fracture according to AO-OTA type 11-B2 or 11-C2. The primary outcomes are active ROM and shoulder function (Constant score). Secondary outcomes have been patient self-assessment form (Simple shoulder test) and radiographical details. Follow-up takes place at the moment of clinical observation with rx control. Results: We analyzed a group of 23 patients treated by plate and screws and 21 patients treated by rTSA with these average results. ORIF: Flexion 112.8°, Abduction 99.6°, External rotation at 90° 47.4°, modal Internal rotation hand at Sacroiliac joint, Constant Score 52.9 and Simple Shoulder Test 8.0. RSA: Flexion 133.3°, Abduction 101.4°, External rotation at 90° of abduction 35.5°, modal Internal rotation hand at waist (L3), Constant Score 65.9 and Simple Shoulder Test 9.2. No nerve injuries were reported. No cases of pseudo-arthrosis or plate fractures. No arthroplasty implant loosening, infection or dislocation was documented and revision required. Conclusion: Our study shows good clinical outcomes and fewer complications in both treatment options. Better clinical and daily living results are reported in RSA compared with ORIF, confirming that rTSA is one of the best treatment in proximal humeral fractures in the elderly patients, which rotator cuff status frequently is poor and degenerating. The few radiological complications do not seem to have influence on active ROM and Constant Score, both the first and the second group of patients. Level of evidence: Level IV, Case Series, Surgical.

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