High BMI has been classically regarded as a contraindication for unicompartmental knee arthroplasty (UKA) as it can potentially lead to poor clinical outcomes and a higher risk of failure. In recent years, UKA has increased in popularity and, as a result, patient selection criteria are beginning to broaden. However, UKA performed manually continues to be technically challenging and surgical technique errors may result in suboptimal implant positioning. UKA performed with robotic assistance has been shown to improve component positioning, overall limb alignment, and ligament balancing, resulting in overall improved clinical outcomes. The purpose of this study is to examine the effect of high BMI in patients receiving UKA with robotic assistance. 1007 patients (1135 knees) were identified in an initial and consecutive multi-surgeon multi-center series receiving robotically assisted medial UKA, with a fixed bearing metal backed onlay tibial component. As part of an IRB approved study, every patient in the series was contacted at a minimum two year (±2 months) follow up and asked a series of questions to determine implant survivorship and satisfaction. 160 patients were lost to follow up, 35 patients declined to participate, and 15 patients were deceased. 797 patients (909 knees) at a minimum two year follow up enrolled in the study for an enrollment rate of 80%. 45% of the patients were female. The average age at time of surgery was 69.0 ± 9.5 (range: 39–93). BMI data was available for 887 knees; the average BMI at time of surgery was 29.4 ± 4.9. Patients were stratified in to five categories based on their BMI: normal (< 25; 16%), overweight (25–30; 46%), obese class I (30–35; 25%), obese class II (35–40; 11%) and obese class III (>40; 2%).Introduction
Methods
This is a case report of a 78 year old male who underwent outpatient mini-incision medial UKA using the haptic robotic guidance. The patient subsequently suffered a traumatic lateral meniscus tear and underwent a lateral compartment UKA with the same robotic system instead of converting to a total knee replacement at one year post op and is now 2 years post op on the lateral side as well. The patient is a 74 year old male with a BMI of 27, suffering from OA of the right knee. He had a previous TKA on his left side by another surgeon that was followed with a lateral release by still another surgeon with fair to good satisfaction currently; however he did not want another TKA. He had multiple aspirations and injections of corticosteroids for arthritic effusions on his right knee that were moderate to severe and painful. On 7/6/2010 he underwent a right medial UKA using with robotic guidance. The patient had a subsequent injury to his lateral meniscus causing pain for which multiple options were discussed with the patient. The informed patient chose to have a lateral compartment arthroplasty. On 6/21/2011 a lateral compartment UKA was performed on the same patient's right knee through a second mini-lateral incision again using robotic guidance.Introduction:
Methods:
Unicompartmental knee arthroplasty has been shown to have lower morbidity, quicker rehabilitation and more normal kinematics compared to conventional TKA, but subchondral defects, or severe osteoarthritic changes, of the medial compartment may complicate component positioning. Successful UKA in these patients requires proper planning and exact placement of the components to ensure adequate and stable fixation and proper postoperative kinematics. This study presents a series of three patients with spontaneous osteonecrosis of the knee receiving a UKA with CT-based haptic robotic guidance. This series includes two females and one male with spontaneous osteonecrosis of the medial femoral condyle who underwent outpatient mini-incision medial UKA using the MAKO Surgical Rio Robotic Arm System. Pre-operatively all patients were found to have pain with weight bearing that would not improve despite non-arthroplasty treatment.Introduction:
Methods:
UKA allows replacement of a single compartment in patients who have isolated osteoarthritis. However, limited visualization of the surgical site and lack of patient-specific planning provides challenges in ensuring accurate alignment and placement of the prostheses. Robotic technology provides three-dimensional pre-op planning, intra-operative ligament balancing and haptic guidance of bone preparation to mitigate the risks inherent with current manual instrumentation. The aim of this study is to examine the clinical outcomes of a large series of robot-assisted UKA patients. The results of 500 consecutive medial UKAs performed by a single surgeon with the use of a metal backed, cemented prosthesis installed with haptic robotic guidance. The average age of the patients at the time of the index procedure was 71.1 years (range was 40 to 93 years). The average height was 68 inches (range 58″–77″) and the average weight was 192.0 pounds (range 104–339 pounds). There were 309 males and 191 females. The follow-up ranges from 2 weeks to 44 months.Introduction:
Methods:
Successful clinical outcomes following unicompartmental knee arthroplasty (UKA) depend on component positioning, soft tissue balance and overall limb alignment which can be difficult to achieve using manual instrumentation. Recently, robotically guided technology has been used to improve post-operative implant positioning, and limb alignment in UKA with the expectation that this will result in greater implant longevity. This multi-center study examines the survivorship of this robotically guided procedure coupled with a novel, anatomically designed UKA implant at two years follow up. This study examines the two year survivorship and patient satisfaction of an anatomically designed UKA implant using a new robotically guided technology that has been shown to improve implant positioning and alignment.INTRODUCTION
OBJECTIVES
Isolated lateral compartment osteoarthritis (OA) occurs in 5–10% of knees with unicompartmental OA. Lateral unicompartmental knee arthroplasty has been limited in its prevalence due to challenging surgical technique issues. A robotic-arm assisted surgical technique has emerged as a way to achieve precise implant positioning which can potentially improve surgical outcomes. 63 consecutive lateral unicompartmental knee arthroplasties were performed by a single surgeon with the use of a metal backed, cemented prosthesis installed with the three-dimensional intra-operative kinematics and haptic robotic guidance. The average age of the patient was 72.7 years (range: 59–87) and the average BMI was 27.2 (range: 19.0–38.6). The follow-up ranged from 2 months to 30 months.Introduction:
Methods:
Post-traumatic knee arthritis can cause malalignment and severe disability depending upon the extent of injury. Despite young age of the patient, joint replacement may be needed to restore alignment and function when neurovascular structures and the extensor mechanism have been spared. The types of injuries that are of main concern can be categorised as: articular crush, condylar split, shaft involvement, ligamentous deficiency or a combination of these. Implant choices depend upon the severity of the bone or soft tissue involvement and would fall into 3 main options: 1.) resurfacing type; 2.) modular type with or without osteotomy; and 3.) modular varus- valgus constrained or rotating-hinge type with or without osteotomy. Patello-femoral options include: patellar resurfacing or patelloplasty; patella tendon graft in patellectomised knees; and repair or allograft of the extensor mechanism. Good or excellent clinical outcomes have been appreciated in the majority of such cases treated over the past 20 years using these guidelines.
Dislocation after primary total hip replacement (THR) can occur within days or weeks after the index procedure because of malpositioned components or be of late onset years later due to trauma or excessive wear. Regardless of timing, the culprit causing dislocation is catastrophic neck-cup impingement, which levers the prosthetic head out of the prosthetic socket. Prosthetic range of motion (P-ROM), which is determined by the diameter of the femoral neck at the ball-neck junction and the distance to the edge of the prosthetic cup, must be considered during initial THR insertion to allow internal and external hip rotation of 45° at 90° of hip flexion in neutral abduction-adduction. Failure to achieve satisfactory P-ROM by accurate placement of the acetabular cup and femoral component may result in multiple re-dislocations, especially if periprosthetic capsular reformation is interrupted by an initial dislocation, which disrupts the primary surgical repair. If component position is satisfactory but traumatic disruption of the periprosthetic capsule results in recurrent posterior THR dislocation, a posterior capsular reefing and reinforcement with mersilene tape can be used. A postoperative 30° hip abduction brace with a 60° flexion stop is recommended for continuous use for 6 to 12 weeks. If component position is unsatisfactory or excessive wear causes impingement, removal and repositioning of the acetabular cup in 30° anteversion and 60° abduction with 15° of femoral neck anteversion is recommended.
