Robot-Assisted Unicompartmental Knee Arthroplasty: Increasing Surgical Accuracy? A Cadaveric Study.

Unicompartmental knee arthroplasty (UKA) represents 10% of knee arthroplasties. Advantages are better functional results, quicker recovery, shorter hospitalization time, and lower blood loss, among others. However, revision rates are larger than total knee arthroplasty. Among the most important factors that explain this are the implant position and alignment, and the correct surgical indication. Greater accuracy in the implant placement may improve clinical results and increase the rate of implant survival. The objective of this study is to evaluate the precision of the Navio robot-assisted system in the position and alignment of medial UKA compared with the conventional technique. This is an experimental pilot study. Twenty-six cadaveric models were randomized into 2 groups: Robot-Assisted surgery (R) and Conventional Surgery (C). Radiological study was performed pre- and post-surgery, evaluating the medial distal femoral angle (MDFA), medial proximal tibial angle (MPTA), tibial slope, tibiofemoral angle (TFA), sagittal femoral angle (SFA), and size of the femoral and tibial components. The main result measurement was the change in postoperative angulation. The results of this study are MDFA median of 1.07° (0.19-4.5) for group R and 0.12° (0.03-10.4) with a significant difference in variances; a Welch t-test of p = 0.013; and an MPTA of 1.28° (0.05-5.87) for R and 1.3°(0.08-14.1) for C with significantly different variances (p = 0.0064). Size of the femoral component has a difference of p < 0.05 between groups. No differences for dispersion of TFA nor for the size of the tibial component were observed. In conclusion, using robot-assisted UKA allows for greater accuracy in the positioning of the implants and in the prediction of the size of the femoral component.

Robotic-assisted vs conventional surgery in medial unicompartmental knee arthroplasty: a clinical and radiological study.

BACKGROUND: The use of unicompartmental knee arthroplasty (UKA) has increased and new technologies have been developed to improve patient survival and satisfaction, soft tissue balance, alignment, and component size. Robot-assisted systems offer an increase in surgical precision and accuracy. The purpose of this study is to evaluate the precision of component position using five radiological parameters in conventional and robotic-assisted medial UKA using the NAVIO system. METHODS: A cohort study was designed for patients who underwent medial UKA between April 2017 and March 2019 in a single center. Patients were allocated in the conventional (UKA-C) or robotic-assisted (UKA-R) group. The variables analyzed were age, gender, affected knee side, length of hospital stay, surgical time, and radiological measurements such as anatomical medial distal femoral angle (aMDFA), anatomical medial proximal tibial angle (aMPTA), tibial slope, the sagittal femoral angle, and the component size. A target was defined for each measurement, and a successful UKA was defined if at least four radiological measures were on target after surgery. Also, patients' reported outcomes were evaluated using the Oxford Knee Score (OKS) and a numeric rating scale (NRS) for pain. RESULTS: Thirty-four patients were included, 18 of them underwent UKA-R. The success rate for UKA in the UKA-R group was 87%; meanwhile, in the UKA-C group this was 28%, this difference was significant and powered (Fisher's exact test, p = 0.001; 1 - ß = 0.95). Also, a 5-point difference in favor of the UKA-R group in the median OKS (p = 0.01), and a significantly lower median NRS for pain (p < 0.000) were found after surgery. CONCLUSIONS: UKA-R achieved more precision in the radiological parameters' measure in this study. Also, UKA-R has a trend towards a better OKS and a lower NRS for pain at short-term follow-up.

Dynamic-Anatomical Reconstruction of Medial Patellofemoral Ligament in Open Physis.

Patellar dislocation is a common knee problem, 10 times more frequent in childhood and adolescence. Medial patellofemoral ligament is injured up to 94% of the time, and its reconstruction is effective in terms of stabilization of the patella. However, distal femoral physis can be damaged with different techniques of reconstruction, due to the location of the femoral footprint. The purpose of this Technical Note is to describe a quasi-anatomical and dynamic reconstruction of the medial patellofemoral ligament, using no tunnel in the femur, passing the graft behind the adductor tendon, and fixing it with one tunnel in the patella and one passage through the quadriceps tendon.

Robotic-assisted Unicompartmental knee Arthroplasty optimizes joint line restitution better than conventional surgery.

PURPOSE: To compare joint line restoration after unicompartmental knee arthroplasty (UKA) between conventional and robotic-assisted surgery. Previous studies have shown that joint line distalization can lead to higher failure rates. The hypothesis was that robotic-assisted UKA is associated with less femoral component distalization and a precise tibial cut, which allows a more anatomical restitution of the knee joint line. METHODS: Retrospective cohort study of patients undergoing medial or lateral UKA between May 2018 and March 2020. Preoperative and postoperative radiologic assessment of the joint line was performed by two observers, using three different methods, one for tibial slope and one for tibial resection. Robotic assisted UKA and conventional UKA groups were compared. RESULTS: Sixty UKA were included, of which 48 (77.42%) were medial. Robotic-assisted UKA were 40 (64.52%) and 22(35.48%) were conventional The distalization of the femoral component was higher in the conventional group despite the method of measurement used In both Weber methods, the difference was statistically different: Conventional 2.3 (0.9 to 5.6) v/s Robotic 1.5 (- 1.1 to 4.1) (p =0.0025*). A higher proportion of patients achieved a femoral component position ≤ two millimeters from the joint line using robotic-assisted UKA compared to the conventional technique . No statistical difference between robotic-assisted and conventional UKA was found in tibial resection and slope. CONCLUSION: Robotic-assisted UKA shows a better rate of joint line restoration due to less femoral component distalization than conventional UKA. No difference was found in the amount of tibial resection between groups in this study. LEVEL OF EVIDENCE: III.

Meniscal Ramp Lesion Repair Using an All-Inside Technique.

Posteromedial meniscotibial ligament lesions, known as meniscal ramp lesions, are typically associated with ACL injuries, but frequently underdiagnosed. When correctly diagnosed, repair is mandatory in most cases. Retraction of the soft tissues makes it difficult to repair and leads to suture failure. Previously described techniques include all-inside and inside-out meniscal sutures, but do not ensure correct meniscotibial closure because of the soft tissue retraction. The purpose of this Technical Note is to describe a meniscal ramp lesion arthroscopic repair with an all-inside technique with the Fast-Fix 360 device, detailing the use of the accessory posteromedial portal, and the addition of an arthroscopic grasper that raises the retracted meniscotibial ligament, to allow correct fixation.

Menisco lateral hipermóvil: diagnóstico y tratamiento de lesiones de fascículos poplíteo meniscales / Hypermobile lateral meniscus: diagnosis and treatment of popliteomeniscal fasciculi injuries

El Síndrome de Menisco Hipermóvil, caracterizado por bloqueos mecánicos dolorosos de la rodilla, tiene un sustento anatómico basado en los fascículos poplíteo meniscales anteroinferior y posterosuperior, responsables de la estabilidad primaria de la esquina posterolateral meniscal. Con un cuadro clínico característico, usualmente con Resonancia Magnética sin hallazgos sugerentes de patología, la artroscopía juega un rol esencial en casos de alta sospecha, comprobando el diagnóstico al presentar hipermobilidad del cuerno posterior del menisco lateral. MÉTODO: Se presentan 9 casos resueltos, con hiperlaxitud posterolateral meniscal, y presentación clínica caracterizada por bloqueo articular de rodilla sin causa aparente. En todos los casos se realizó reparación de los fascículos poplíteo meniscales con suturas meniscales, con resolución completa de la sintomatología y sin complicaciones post quirúrgicas. CONCLUSIÓN: El manejo del cuadro de menisco hipermóvil está basado por la sospecha clínica y el descarte de otras patologías como causa subyacente de la sintomatología. El manejo quirúrgico con suturas meniscales ha demostrado restaurar la biomecánica normal del compartimento posterolateral de la rodilla, logrando la resolución completa de los síntomas. NIVEL DE EVIDENCIA: IV.

Hypermobile Meniscus Syndrome, characterized by painful mechanical blockages of the knee, has an anatomical support based on the anteroinferior and posterosuperior poplíteomeniscal fascicles, responsible for the primary stability of the posterolateral meniscal corner. With a characteristic clinical presentation, usually with Magnetic Resonance without suggestive findings of pathology, arthroscopy plays an essential role in cases of high suspicion, checking the diagnosis by presenting hypermobility of the posterior horn of the lateral meniscus. METHOD: We present 9 resolved cases, with posterolateral meniscal hypermobility, and clinical presentation characterized by knee articular block without apparent cause. In all cases, poplíteomeniscal fascicles were repaired with meniscal sutures, with complete resolution of the symptoms and without post-surgical complications. CONCLUSION: The management of the hypermobile meniscus syndrome is based on clinical suspicion and the discarding of other pathologies as the underlying cause of the symptomatology. Surgical management with meniscal sutures has been shown to restore the normal biomechanics of the posterolateral compartment of the knee, achieving complete resolution of symptoms. LEVEL OF EVIDENCE: Case series IV.