Is 80% satisfaction still the expectation in modern TKA mechanically aligned with robot assist? We think not.

Several studies reported that20% of patients were unhappy with the outcome of their total knee arthroplasty (TKA). Having commenced robot assist TKA whilst maintaining the goal of implanting the prosthesis to a neutral mechanical axis, we reviewed our patients to find out if we also have a 20% rate of patients being unhappy with the outcome of their knee replacement surgery. We hypothesized that rate of patient satisfaction would be higher than 90% with robot-surgical assistant (ROSA) technique. The first 175 patients who underwent ROSA TKA were reviewed at a minimum of 1 year postoperatively. All TKAs were performed using ROSA technique with Persona cementless prosthesis aiming to restore neutral mechanical coronal alignment with flexion gap balancing. We investigated whether or not the patients were happy they had their knee replacement surgery and whether they were happy with the outcome. 165 (94%) of 175 patients, were contactable with 1 deceased and 9 uncontactable. From the 165 patients who participated in the study, 95% of patients were happy they had the surgery done and 93% were happy with the outcome of their knee replacement. A sub analysis showed that patients who had simultaneous bilateral TKA were significantly less likely to be happy than staged procedures (p < 0.05). Total knee replacement utilising robot technique with modern implants and aiming for mechanical coronal alignment of the implants to restore the mechanical axis with flexion gap balancing may result in > 90% of patients being happy with the outcome of their surgery.

Incidence of soft tissue releases in robotic assisted cementless TKA with mechanical alignment and flexion gap balancing.

BACKGROUND: To ensure the success of total knee arthroplasty (TKA), precise bone cuts and a well-balanced soft tissue envelope are crucial. Soft tissue release may be necessary, subject to various factors. Therefore, documenting the type, frequency, and necessity of soft tissue releases can establish a benchmark for comparing different alignment techniques and philosophies and evaluating their outcomes. The purpose of this study was to demonstrate that robotic-assisted knee surgery requires minimal soft tissue release. METHODS: We prospectively documented and retrospectively reviewed the soft tissue releases employed in securing ligament balance in the first 175 patients who received robotic-assisted TKAs at Nepean Hospital. ROSA was utilized in all surgeries with the aim of restoring mechanical coronal alignment, with a flexion gap balancing technique. Surgeries were performed between December 2019 to August 2021 by a single surgeon who used a standard medial parapatellar approach without a tourniquet, and the cementless persona prosthesis. All patients were followed up for a minimum of 6 months post-surgery. Soft tissue releases included any form of medial release for varus knee, posterolateral release for valgus knee and PCL fenestration or sacrifice. RESULTS: There were 131 female and 44 male patients, aged between 48 to 89 years (average 60 years). The preoperative HKA ranged from 22 degrees varus to 28 degrees valgus, with 71% of patients presenting with a varus deformity. For the whole group, the no need for soft tissue release was documented in 123 patients (70.3%), small fenestrated releases of PCL in 27 (15.4%), sacrifice of PCL in 8 (4.5%), medial releases in 4 (2.3%) and posterolateral releases in 13 (7.4%). In 29.7% of patients in whom a soft tissue release was necessary for balance, over half were/received minor fenestrations of the PCL. Outcomes to date included no revisions or impending revisions, 2 MUAs (1%), and Oxford knee scores averaged 40 at 6 months. CONCLUSION: We concluded that Robot technology enhanced the precision of bone cuts and allowed for titration of required soft tissue releases to achieve optimal balance.

Tissue-Engineered Hydroxyapatite Bone Scaffold Impregnated with Osteoprogenitor Cells Promotes Bone Regeneration in Sheep Model.

BACKGROUND: Managing massive bone defects, a great challenge to orthopaedics reconstructive surgery. The problem arise is the supply of suitable bone is limited with many complications. Tissue-engineered hydroxyapatite bone (TEHB) scaffold impregnated with osteoprogenitor cells developed as an alternative to promote bone regeneration. METHODS: This animal protocol has been approved by Universiti Kebangsaan Malaysia Animal Ethical Committee. The TEHB scaffold prepared from hydroxyapatite using gel casting method. A total of six adolescent female sheep were chosen for this study. Later, all the sheep were euthanized in a proper manner and the bone harvested for biomechanical study. Bone marrow was collected from iliac crest of the sheep and bone marrow stem cells (BMSCs) isolated and cultured. BMSCs then cultured in osteogenic medium for osteoprogenitor cells development and the plasma collected was seeded with osteoprogenitor cells mixed with calcium chloride. Bone defect of 3 cm length of tibia bone created from each sheep leg and implanted with autologous and TEHB scaffold in 2 different groups of sheep. Wound site was monitored weekly until the wound completely healed and conventional X-ray performed at week 1 and 24. Shear test was conducted to determine the shear force on the autologous bone and TEHB scaffold after implantation for 24 weeks. RESULTS: All of the sheep survived without any complications during the study period and radiograph showed new bone formation. Later, the bone harvested was for biomechanical study. The highest shear force for the autologous group was 13 MPa and the lowest was 5 MPa while for the scaffold group, the highest was 10 MPa and the lowest was 3 MPa. Although, proximal and distal interface of autologous bone graft shows higher shear strength compared to the TEHB scaffold but there is no significant difference in both groups, p value > 0.05. Histologically in both proximal and distal interface in both arms shows bone healing and woven bone formation. CONCLUSION: TEHB scaffold impregnated with osteoprogenitor cells has the potential to be developed as a bone substitute in view of its strength and capability to promote bone regeneration.