Knee loading stimulates healing of mouse bone wounds in a femur neck

Abstract

Healing of bone wounds is sensitive to various environmental stimuli. Using knee loading, which has been shown to stimulate bone formation in mouse femora and tibiae, we addressed a question: Does knee loading accelerate a closure of open wounds in a femur neck? A surgical wound (0.5 mm in diameter) was generated at the femur neck in the left and right femora of C57/BL/6 female mice, and knee loading was applied to the left knee for 3 min/day for 3 consecutive days. Surgical holes at the femoral midshaft were used as control. Animals were sacrificed 1, 2, and 3 weeks after surgery for analyses with µCT and pQCT as well as mechanical testing. The results showed load-driven acceleration of the closure of surgical holes. Compared to a sham-loaded contralateral control, knee loading reduced the size of surgical wounds in the femoral midshaft by 14% (p < 0.05), 21% (p < 0.01), and 32% (p < 0.001) in 1, 2, and 3 weeks, respectively. It also decreased the wound size in the femur neck by 16% (p < 0.001; 1 week), 18% (p < 0.001; 2 weeks), and 21% (p < 0.001; 3 weeks). Images with pQCT revealed that bone mineral density (BMD) was increased from 571 ± 19 mg/cm3 (control) to 686 ± 19 mg/cm3 (loaded) (p < 0.01), and bone mineral content (BMC) from 3.05 ± 0.12 mg/mm (control) to 3.42 ± 0.11 mg/mm (loaded) (p < 0.05). Furthermore, mechanical testing showed that stiffness of the femur was increased by knee loading (p < 0.05). This study demonstrates that knee loading is capable of accelerating healing of surgical wounds throughout the femur including the femoral midshaft and neck.

Development of an Artificial Finger-Like Knee Loading Device to Promote Bone Health

“…A controlled mechanical loading was then applied on a periodic basis. It was observed that the surgical holes healed quickly in the femur with mechanical loading than the contralateral femur without mechanical loading [15]. This observation supports the notion that direct mechanical loading is an effective treatment to accelerate healing of bone injuries.…”

Knee loading protects against osteonecrosis of the femoral head by enhancing vessel remodeling and bone healing

“…Loading synovial joints such as the knee and ankle has been demonstrated to accelerate the healing of surgical wounds in the femoral neck and tibia, respectively [15, 17]. Joint loading is also reported to elevate the length of mouse limbs [47, 48].…”

“…Joint loading have been applied to synovial joints such as the elbow, knee and ankle [15]. In our previous studies, joint loading were applied 3 to 5 min per day for 2 to 3 weeks.…”

“…Our bone histomorphometric studies demonstrated that knee loading stimulates bone formation [16]. We have also demonstrated that knee loading can accelerate the healing of surgical wounds in the femoral neck and tibia [15, 17]. …”

A Mechatronic Loading Device to Stimulate Bone Growth via a Human Knee

“…An experimental mechanical loading setup was used to apply loading force on one of the injured knees, and the other knee was allowed to heal via remote endocrine signaling [7]. During the loading and recovery phases, the samples of the mouse femur were analyzed, and it was found that the frequent knee-loading helped in accelerated healing and closure of the hole on the femur bone rather than the other knee of the mice [4,5,8]. This experiment attests to the effectiveness of the loading phenomenon in reducing healing time, repair and regeneration of the bones.…”