Advanced technologies, like robotics, provide enhanced precision for implanting total knee arthroplasty (TKA) components; however, optimal component position and limb alignment remain unknown. This study purpose was to identify the ideal target sagittal component position and coronal limb alignment that produce optimal clinical outcomes. A retrospective review of 1,091 consecutive TKAs was performed. All TKAs were PCL retaining or sacrificing with anterior lipped (49.4%) or conforming bearings (50.6%) performed with modern perioperative protocols. Posterior tibial slope, femoral flexion, and tibiofemoral limb alignment were measured with a standardized protocols. Patients were grouped by the ‘how often does your knee feel normal?’ outcome score at latest follow-up. Machine learning algorithms were used to identify optimal alignment zones which predicted improved outcomes scores.Background
Methods
t is accepted dogma in total knee arthroplasty (TKA) that resecting the posterior cruciate ligament (PCL) increases the flexion space by approximately 4mm, which significantly affects intra-operative decisions and surgical techniques. Unfortunately, this doctrine is based on historical cadaveric studies of limited size. This study purpose was to more accurately determine the effect of PCL resection on the tibiofemoral flexion gap dimension Tibiofemoral joint space measurements were made during 127 standardized TKAs by two arthroplasty surgeons. A medial parapatellar approach, computer navigation and provisional tibial and femoral bone cuts were performed in all cases with particular attention to preserving PCL integrity. Cases with an incompetent or damaged PCL were excluded. The tibiofemoral gap dimension was measured with a calibrated tension device at full extension, 45-degrees, and 90-degrees before and after complete PCL resection.Introduction
Methods
Maintaining posterior stability in total knee arthroplasty (TKA) may be achieved by using a posterior stabilized TKA, retaining and balancing the posterior cruciate ligament (PCL) using a traditional cruciate-retaining design (CR), or by increasing the sagittal plane conformity of the tibial insert. In the latter case, stability is achieved by the addition of an anterior buildup on the tibial polyethylene creating the so-called “anterior stabilized” (AS) design. We hypothesized that using an AS tibial insert would provide similar function and survivorship as compared to using a more traditional CR bearing when the PCL is either recessed or balanced. Between 2004 and 2016, 1,731 modular CR TKAs were implanted in 1,509 patients using the same CR TKA design. The diagnosis was osteoarthritis in 98%. 58% of patients were female. Average age of 64.9 years. Within this group, 868 TKAs (50.1%) had a standard CR tibial bearing (3-degree posterior slope and no posterior lip) implanted (CR-S). 480 TKAs (27.8%) had a lipped CR modular tibial bearing (2.5 mm elevated posterior lip) implanted (CR-L). Starting in 2013, 383 TKAs (22.1%) were implanted with an AS modular tibial bearing (9–11 mm anterior lip and a 5 mm posterior lip). If the PCL was considered non-functional or absent, an AS bearing was placed. If the PCL was considered functional, a standard bearing or lipped bearing was used. Clinical and radiographic analysis was performed according to the Knee Society (KS) grading system. The most recent clinical and radiographic evaluation was used for post-operative analysis. The average follow-up in the entire cohort of TKAs was 5.5 years (range 2 to 14.3 years). Kaplan-Meier analysis was used to determine prosthesis survivorship with failure defined as aseptic loosening of the prosthesis (with or without revision) or tibial insert exchange.Introduction
Methods
Existing studies report more accurate implant placement with robotic-assisted unicompartmental knee arthroplasty (UKA); however, surgeon experience has not always been accounted for. The purpose of this study was to compare the accuracy of an experienced, high-volume surgeon to published data on robotic-assisted UKA tibial component alignment. One hundred thirty-one consecutive manual UKAs performed by a single surgeon using a cemented, fixed bearing implant were radiographically reviewed by an independent reviewer to avoid surgeon bias. Native and tibial implant slope and coronal alignment were measured on pre- and postoperative lateral and anteroposterior radiographs, respectively. Manual targets were set within 2° of native tibial slope and 0 to 2° varus tibial component alignment. Deviations from target were calculated as root mean square (RMS) errors and were compared to robotic-assisted UKA data.Introduction
Methods
