Estrogen fluctuations have been implicated in the soft tissue injury gender-bias due to the hormones effect on the viscoelastic properties. The isolated effect of estrogen on the mechanical behaviour of human tendon is unknown. The purpose of this study was to elucidate the effect of circulating levels of estrogen on the strain properties of the human Achilles tendon.

Twenty females (18–35 years) who were using the pill together with 20 matched, non-pill users, participated in this study. Non-pill users were tested at the time of lowest (menstruation) and highest (ovulation) estrogen whilst pill users, who exhibited constant and attenuated estrogen levels, were tested at menstruation and two weeks later. At each test session, maximal isometric plantarflexion efforts were performed on a calf-raise apparatus whilst synchronous real-time ultrasonography of the triceps surae aponeurosis was recorded. Connective tissue length (Lo) of the triceps surae complex was measured and tendon strain was calculated by dividing aponeurosis displacement during plantarflexion by Lo.

Repeated measures ANOVA revealed a significant (p < 0.05) main effect of subject group with significantly higher Achilles strain rates (16.1%) in the non-pill users compared to the pill users. Augmented Achilles tendon strain was associated with higher average estrogen levels in non-pill users.

Those results suggest that higher estrogen levels diminish the joint stabilising capacity of the triceps surae musculotendinous unit and may alter the energy storage capacity of the Achilles tendon during stretch-shorten cycle activities. This may result in a higher incidence of injuries during periods of high estrogen concentration.

Good perioperative analgesia following Total Knee Replacement facilitates rehabilitation and may reduce hospital stay. A multimodal drug injection has been shown to provide excellent pain control and functional recovery, and was introduced into the operating practice of one Arthroplasty surgeon during his Total Knee Replacements.

We compared the rehabilitation of 27 consecutive patients (group 1) following their Total Knee Replacement under spinal anaesthesia receiving the periarticular infiltration mixture, consisting of levobupivacaine, ketorolac and adrenaline at the end of surgery. Their rehabilitation was compared to group 2, a historical group operated on by the same surgeon before the introduction of the multimodal drug injection. These patients were age and sex matched and had received a Femoral and Sciatic block at the time of their operation.

Patients in group 1 had lower analgesic and anti-emetic requirements than group 2. Group 1 also had a shorter time to Strait Leg raise.

Periarticular multimodal drug injection can improve perioperative analgesia and mobilisation following Total Knee Replacement as well as reducing opioid side effects.