Aims. Approximately 10% to 20% of knee arthroplasty patients are not satisfied with the result, while a clear indication for revision surgery might not be present. Therapeutic options for these patients, who often lack adequate quadriceps strength, are limited. Therefore, the primary aim of this study was to evaluate the clinical effect of a novel rehabilitation protocol that combines low-load resistance training (LL-RT) with blood flow restriction (BFR). Methods. Between May 2022 and March 2024, we enrolled 45 dissatisfied knee arthroplasty patients who lacked any clear indication for revision to this prospective cohort study. All patients were at least six months post-surgery and had undergone conventional physiotherapy previously. The patients participated in a supervised LL-RT combined with BFR in 18 sessions. Primary assessments included the following patient-reported outcome measures (PROMs): Knee injury and Osteoarthritis Outcome Score (KOOS); Knee Society Score: satisfaction (KSSs); the EuroQol five-dimension five-level questionnaire (EQ-5D-5L); and the pain catastrophizing scale (PCS). Functionality was assessed using the six-minute walk Test (6MWT) and the 30-second chair stand test (30CST). Follow-up timepoints were at baseline, six weeks, three months, and six months after the start. Results. Six weeks of BFR with LL-RT improved all the PROMs except the sports subscale of the KOOS compared to baseline. Highest improvements after six weeks were found for quality of life (QoL) (mean 28.2 (SD 17.2) vs 19 (SD 14.7); p = 0.002), activities of daily living (mean 54.7 (SD 18.7) vs 42.9 (SD 17.3); p < 0.001), and KSSs (mean 17.1 (SD 8.8) vs 12.8 (SD 6.7); p < 0.001). PROMs improvements continued to be present at three-month and six-month follow-up compared to baseline. However, no significant differences were observed in the paired comparisons of the six-week, three-month, and six-month follow-up. The same trends are observed for the 6MWT and 30CST. Conclusion. The reported regime demonstrates improved QoL and function of dissatisfied knee arthroplasty patients. In light of this, the pathway described may provide a valuable and safe treatment option for dissatisfied knee arthroplasty patients for whom therapeutic options are limited. Cite this article: Bone Joint J 2024;106-B(12):1416–1425

Introduction and Aim. Quadriceps strength is crucial for physical function in patients with knee osteoarthritis (KOA). This study aimed to investigate the effect of combining blood flow restriction (BFR) with low-intensity training (LIT) on quadricep strength in patients with advanced KOA. Methods. Patients with advanced KOA were block randomized by gender into the control or BFR group. The control group received LIT with leg press (LP) and knee extension (KE) at 30% of 1-repetition maximum (1-RM), while the BFR group underwent the same training with 70% limb occlusion. Physical function and patient-reported outcomes were assessed up to 16 weeks. Results. A total of 42 patients were analyzed: 22 in the BFR group (9 males, 13 females) and 20 in the control group (8 males, 12 females). In the BFR group, males exhibited increased KE power from the 4th to the 16th week (p<0.05) and LP power from the 4th to the 12th week (p<0.05). Females in the BFR group showed increased KE power in the 4th and 12th weeks (p<0.05), and LP power increased from the 4th to the 16th week (p<0.05). Males also had improved TSS at the 12th week, while females had improved TSS from the 8th to the 16th week. In the control group, males did not experience an increase in quadricep power. Females, however, had increased KE power in the 4th, 12th, and 16th weeks (p<0.05), and LP power from the 4th to the 12th week (p<0.05). Females in the control group also had improved TSS at the 4th week. Patient-reported outcomes did not differ, and all patients tolerated the training without any dropouts or adverse events. Conclusion. Combining BFR with LIT significantly improved quadricep power and physical function in both genders of KOA patients without exacerbating symptoms

Abstract. Source of Study: London, United Kingdom. This intervention study was conducted to assess two developing protocols for quadriceps and hamstring rehabilitation: Blood Flow Restriction (BFR) and Neuromuscular Electrical Stimulation Training (NMES). BFR involves the application of an external compression cuff to the proximal thigh. In NMES training a portable electrical stimulation unit is connected to the limb via 4 electrodes. In both training modalities, following device application, a standardised set of exercises were performed by all participants. BFR and NMES have been developed to assist with rehabilitation following lower limb trauma and surgery. They offer an alternative for individuals who are unable to tolerate the high mechanical stresses associated with traditional rehabilitation programmes. The use of BFR and NMES in this study was compared across a total of 20 participants. Following allocation into one of the training programmes, the individuals completed training programmes across a 4-week period. Post-intervention outcomes were assessed using Surface Electromyography (EMG) which recorded EMG amplitude values for the following muscles: Vastus Medialis, Vastus Lateralis, Rectus Femoris and Semitendinosus. Increased Semitendinosus muscle activation was observed post intervention in both BFR and NMES training groups. Statistically significant differences between the two groups was not identified. Larger scale randomised-controlled trials are recommended to further assess for possible treatment effects in these promising training modalities

7–20 % of the patients with a total knee arthroplasty (TKA) are dissatisfied without an indication for revision. Therapeutic options for this patient population with mostly a lack of quadriceps strength are limited. The purpose of this study is to evaluate the effect of six weeks low load resistance training with blood flow restriction (BFR) on the clinical outcome in these unhappy TKA patients. Thirty-one unhappy TKA patients (of the scheduled fifty patients) without mechanical failure were included in this prospective study since 2022. The patients participate in a supervised resistance training combined with BFR, two times a week during nine weeks. Patients were evaluated by the Knee Osteoarthritis Outcome Score (KOOS), Knee Society Score: satisfaction (KSSs) and the Pain Catastrophizing Scale (PCS). Functionality was tested using the Six Minute Walk Test (6MWT) and the 30-Second Chair Stand Test (30CST). Follow-up took place at six weeks, three months and six months after the start. Six weeks training with BFR provided statistically significant improvements in all the KOOS subscales compared to the baseline, especially for symptoms (55.1 (±15.4) versus 48.0 (±16.5); p<0.001), activities in daily living (50.3 (±21.1) versus 43.7 (±17.2); p<0.00) and quality of life (24.6 (±18.5) versus 17.3 (±13.0); p<0.001). The PCS reduced from 27.4 (±11.0) to 23.2 (±11.4) at six weeks (p<0.01), whereas the KSSs increased from 11.8 (±6.5) to 14.9 (±7.6) (p=0.021). Both the 6MWT and the 30CST improved statistically significant from respectively 319.7 (±15.0) to 341.6m (±106.5) (p<0.01) and 8.6 (±3.9) to 9.3 times (±4.5) (p<0.01). Blood flow restriction appears to enhance the quality of life and functional performance of unhappy TKA patients. Based on these preliminary results, BFR seems to be a promising and valuable alternative for these TKA patients with limited therapeutic options

Aims

The aim of this study was to investigate the global and local impact of fat on bone in obesity by using the diet-induced obese (DIO) mouse model.

Bones can adapt in response to mechanical stimuli; higher rates of loading have been associated with greater bone formation rates. This study determined where bone accretion was localized in response to high loading rates. Non-invasive loads were applied to mice tibiae at one of three rates for four week. It was found, via calcein labels, that adaptation on the periosteal, but not endosteal, surface exhibited a dose-response relation with loading rate; periosteal and endosteal adaptation was localized to regions of high strain gradients. Understanding the stimuli bone responds to may underpin the development of non-pharmacological treatments to enhance bone mass. Bones can adapt to mechanical stimuli; higher rates of loading have been linked with greater bone formation rates (BFR). The purpose of this research was to determine if bone accretion associated with higher loading rates occurs in regions of high strain gradients or strain rates and if adaptation is similar on periosteal and endosteal surfaces. Periosteal but not endosteal surfaces displayed a dose-response relation with loading rate. Adaptation on both periosteal and endosteal surfaces was localized to sectors with high strain gradients. Understanding the precise stimuli by which bone responds may underpin the development of non-pharmacological treatments to enhance bone mass. Tibia loaded at the high rate had significantly greater periosteal BFR, relative to tibiae loaded at medium (> 48 %) and low (> 104 %) rates; adaptation was localized to posterior sectors (high strain gradients). Endosteally, adaptation was localized to regions of high strain gradients (anterior sectors), but did not display a dose-response relation with loading rate. Forty-three skeletally mature C57BL/6 mice were randomly assigned to one of three groups, based on loading rate; low (0.004 ε/s; n = 14), medium (0.020 ε/s; n = 15), and high (0.100 ε/s; n = 14). Loads were applied so that tibiae experienced non-invasive medio-lateral cantilever bending (peak strain = 1000 με) at 1 Hz, 60 s, 5 d/w, for 4 wk. Calcein bone labels were administered on d one and eighteen. A standardized sector of the tibial middiaphyeal shaft was digitally divided into 45° radial sectors, and prepared for histomorphometry. Funding: Funded in part by NSERC, and CIHR

Objectives

Little is known about tissue changes underlying bone marrow lesions (BMLs) in non-weight-bearing joints with osteoarthritis (OA). Our aim was to characterize BMLs in OA of the hand using dynamic histomorphometry. We therefore quantified bone turnover and angiogenesis in subchondral bone at the base of the thumb, and compared the findings with control bone from hip OA.

We investigated the effect of stimulation with a pulsed electromagnetic field on the osseointegration of hydroxyapatite in cortical bone in rabbits. Implants were inserted into femoral cortical bone and were stimulated for six hours per day for three weeks.

Electromagnetic stimulation improved osseointegration of hydroxyapatite compared with animals which did not receive this treatment in terms of direct contact with the bone, the maturity of the bone and mechanical fixation. The highest values of maximum push-out force (F_max) and ultimate shear strength (σ_u) were observed in the treated group and differed significantly from those of the control group at three weeks (F_max; p < 0.0001; σ_u, p < 0.0005).

Carbonate-substituted hydroxyapatite (CHA) is more osteoconductive and more resorbable than hydroxyapatite (HA), but the underlying mode of its action is unclear. We hypothesised that increased resorption of the ceramic by osteoclasts might subsequently upregulate osteoblasts by a coupling mechanism, and sought to test this in a large animal model.

Defects were created in both the lateral femoral condyles of 12 adult sheep. Six were implanted with CHA granules bilaterally, and six with HA. Six of the animals in each group received the bisphosphonate zoledronate (0.05 mg/kg), which inhibits the function of osteoclasts, intra-operatively.

After six weeks bony ingrowth was greater in the CHA implants than in HA, but not in the animals given zoledronate. Functional osteoclasts are necessary for the enhanced osteoconduction seen in CHA compared with HA.