Two-year clinical outcomes and complication rates in anatomic and reverse shoulder arthroplasty implanted with Exactech GPS intraoperative navigation.

INTRODUCTION: We compared the 2-year clinical outcomes of both anatomic and reverse total shoulder arthroplasty (ATSA and RTSA) using intraoperative navigation compared to traditional positioning techniques. We also examined the effect of glenoid implant retroversion on clinical outcomes. HYPOTHESIS: In both ATSA and RTSA, computer navigation would be associated with equal or better outcomes with fewer complications. Final glenoid version and degree of correction would not show outcome differences. MATERIAL AND METHODS: A total of 216 ATSAs and 533 RTSAs were performed using preoperative planning and intraoperative navigation with a minimum of 2-year follow-up. Matched cohorts (2:1) for age, gender, and follow-up for cases without intraoperative navigation were compared using all standard shoulder arthroplasty clinical outcome metrics. Two subanalyses were performed on navigated cases comparing glenoids positioned greater or less than 10° of retroversion and glenoids corrected more or less than 15°. RESULTS: For ASTA, no statistical differences were found between the navigated and non-navigated cohorts for postoperative complications, glenoid implant loosening, or revision rate. No significant differences were seen in any of the ATSA outcome metrics besides higher internal and external rotation in the navigated cohort. For RTSA, the navigated cohort showed an ARR of 1.7% (95% CI 0%, 3.4%) for postoperative complications and 0.7% (95% CI 0.1%, 1.2%) for dislocations. No difference was found in the revision rate, glenoid implant loosening, acromial stress fracture rates, or scapular notching. Navigated RTSA patients demonstrated significant improvements over non-navigated patients in internal rotation, external rotation, maximum lifting weight, the Simple Shoulder Test (SST), Constant, and Shoulder Arthroplasty Smart (SAS) scores. For the navigated subcohorts, ATSA cases with a higher degree of final retroversion showed significant improvement in pain, Constant, American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form (ASES), SST, University of California-Los Angeles shoulder score (UCLA), and Shoulder Pain and Disability Index (SPADI) scores. No significant differences were found in the RTSA subcohort. Higher degrees of version correction showed improvement in external rotation, SST, and Constant scores for ATSA and forward elevation, internal rotation, pain, SST, Constant, ASES, UCLA, SPADI, and SAS scores for RTSA. CONCLUSION: The use of intraoperative navigation shoulder arthroplasty is safe, produces at least equally good outcomes at 2 years as standard instrumentation does without any increased risk of complications. The effect of final implant position above or below 10° of glenoid retroversion and correction more or less than 15° does not negatively impact outcomes.

Intersurgeon and intrasurgeon variability in preoperative planning of anatomic total shoulder arthroplasty: a quantitative comparison of 49 cases planned by 9 surgeons.

BACKGROUND: Preoperative planning software is widely available for most anatomic total shoulder arthroplasty (ATSA) systems. It can be most useful in determining implant selection and placement with advanced glenoid wear. The purpose of this study was to quantify inter- and intrasurgeon variability in preoperative planning of a series of ATSA cases. METHODS: Forty-nine computed tomography scans were planned for ATSA by 9 fellowship-trained shoulder surgeons using the ExactechGPS platform (Exactech Inc., Gainesville, FL, USA). Each case was planned a second time between 4 and 12 weeks later. Variability within and between surgeons was measured for implant type, size, version and inclination correction, and implant face position. Interclass correlation coefficients, Pearson, and Light's kappa coefficients were used for statistical analysis. RESULTS: There was considerable variation in the frequency of augment use between surgeons and between rounds for the same surgeon. Thresholds for augment use also varied between surgeons. Interclass correlation coefficients for intersurgeon variability were 0.37 for version, 0.80 for inclination, 0.36 for implant type, and 0.36 for implant size. Pearson coefficients for intrasurgeon variability were 0.17 for version and 0.53 for inclination. Light's kappa coefficient for implant type was 0.64. CONCLUSIONS: This study demonstrates substantial inter- and intrasurgeon variability in preoperative planning of ATSA. Although the magnitude of differences in correction was small, surgeons differed significantly in the use of augments to achieve the resultant plan. Surgeons differed from each other on thresholds for augment use and maximum allowable residual retroversion. This suggests that there may a range of acceptable corrections for each shoulder rather than a single optimal plan.

Assessment of surgeon variability in preoperative planning of reverse total shoulder arthroplasty: a quantitative comparison of 49 cases planned by 9 surgeons.

BACKGROUND: Preoperative planning software is gaining utility in reverse total shoulder arthroplasty (RTSA), particularly when addressing pathologic glenoid wear. The purpose of this study was to quantify inter- and intrasurgeon variability in preoperative planning a series of RTSA cases to identify differences in how surgeons consider optimal implant placement. This may help identify opportunities to establish consensus when correlating plan differences with clinical data. METHODS: A total of 49 computed tomography scans from actual RTSA cases were planned for RTSA by 9 fellowship-trained shoulder surgeons using the same platform (Exactech GPS, Exactech Inc., Gainesville, FL, USA). Each case was planned a second time 6-12 weeks later. Variability within and between surgeons was measured for implant selection, version correction, inclination correction, and implant face position. Interclass correlation coefficients, and Pearson and Light's kappa coefficient were used for statistical analysis. RESULTS: There was considerable variation in the frequency of augmented baseplate selection between surgeons and between rounds for the same surgeon. Thresholds for augment use also varied between surgeons. Interclass correlation coefficients for intersurgeon variability ranged from 0.43 for version, 0.42 for inclination, and 0.25 for baseplate type. Pearson coefficients for intrasurgeon variability were 0.34 for version and 0.30 for inclination. Light's kappa coefficient for baseplate type was 0.61. CONCLUSIONS: This study demonstrates substantial variability both between surgeons and between rounds for individual surgeons when planning RTSA. Although average differences between plans were relatively small, there were large differences in specific cases suggesting little consensus on optimal planning parameters and opportunities to establish guidelines based on glenoid pathoanatomy. The correlation of preoperative planning with clinical outcomes will help to establish such guidelines.

Sequential 3-dimensional computed tomography analysis of implant position following total shoulder arthroplasty.

BACKGROUND: Detection of postoperative component position and implant shift following total shoulder arthroplasty (TSA) can be challenging using routine imaging. The purpose of this study was to evaluate glenoid component position over time using 3-dimensional computed tomography (CT) analysis with minimum 2-year follow-up. METHODS: Twenty patients underwent primary TSA with sequential CT scanning of the shoulder: a preoperative study, an immediate postoperative study within 2 weeks of surgery, and a postoperative study performed at minimum 2-year follow-up (CT3). Postoperative glenoid component position and central peg osteolysis were assessed across the immediate postoperative CT scan and CT3. Glenoids with evidence of component shift and/or grade 1 central peg osteolysis on CT3 were considered at risk of loosening. RESULTS: Of the patients, 7 (35%) showed evidence of glenoid components at risk of loosening on CT3, 6 with component shift (3 with increased inclination alone, 1 with increased retroversion alone, and 2 with both increased inclination and retroversion). Significantly more patients with glenoid component shift had grade 1 central peg osteolysis on CT3 compared with those without shift (83% vs 7%, P = .002). One clinical failure occurred, with the patient undergoing revision to reverse TSA for rotator cuff deficiency. CONCLUSIONS: Three-dimensional CT imaging analysis following TSA identified changes in glenoid component position over time, with inclination being the most common direction of shift and grade 1 central peg osteolysis commonly associated with shift. These findings raise concern for glenoids at risk of loosening, but further follow-up is needed to determine the long-term clinical impact of these findings.

Biomechanical evaluation of distal biceps tendon repair using tension slide technique and knotless fixation technique.

BACKGROUND: Acute distal biceps tendon ruptures are uncommon injuries that often affect young active males, typically resulting from an eccentric load on their dominant extremity. The purpose of this study was to compare pullout strength and tendon gapping in the tension slide technique (TST) versus a knotless fixation technique (KFT). METHODS: Two sets of experiments were performed using cadaveric elbow specimens. In the first experiment, eight elbows from different cadavers were tested to compare TST with a standard locking whipstitch with KFT, four elbows in each group, using a standard locking whipstitch. In the second experiment, 12 elbows were used to study the differences between TST with a standard locking whipstitch with KFT using suture tape reinforced whipstitch (RKFT), using the TST data from the first and second experiment. Each experiment evaluated gapping after cyclic loading and the second experiment also tested the construct to load to failure. RESULTS: Gapping for KFT with a standard locking whipstitch was 10.64 mm versus 2.69 mm for the TST after 1000 cycles (P = 0.016). A reinforced whipstitch significantly improved the failure to gap on the KFT with no significant difference in gapping when compared to TST after 3000 cycles (P = 0.36). The resultant gapping for TST and KST was 2.08 mm and 2.99 mm (P = 0.91), respectively. Load to failure for TST and KFT were 282 Nm and 328 Nm (P = 0.20), respectively. CONCLUSION: Bone-tendon gap resistance of a KFT repair of a torn distal biceps tendon is limited by suture technique. Using a tape reinforced locking whipstitch, the repair is as strong as TST repair. LEVELS OF EVIDENCE: Basic Science.

Humeral head sizing using extra-articular landmarks on conventional radiographs.

PURPOSE: Proper humeral head (HH) sizing is critical to success in anatomic shoulder replacement for management of glenohumeral arthritis. In this study, we evaluate the accuracy and reliability of using non-articular landmarks on conventional radiographs for HH templating. METHODS: Anatomic HH replacement was performed on five non-arthritic shoulders, from fresh adult cadavers. Pre-operative and post-operative radiographs and 3-D CT scans were obtained. Humeral head size was determined using the articular surface and three extra-articular landmarks (inner aspect of the lateral cortex, the medial footprint of the rotator cuff, and the medial calcar). Two independent observers performed each measurement twice to evaluate reliability. The accuracy was assessed by subtracting the mean values from both the 3D-CT and the implanted HH size measurements. RESULTS: Intraclass correlation coefficient for Observer 1 and 2 for the three-point method showed excellent test-retest reliability 0.996 (95% CI 0.994-0.998) and 0.997 (95% CI 0.995-0.998), respectively. Inter-observer ICC for the three-point method was 0.996 (95% CI 0.994-0.997) showing high level of precision. The three-point method was overestimating the size of the HH (to 3D-CT) with 0.46 ± 0.61 mm on average. The three-point method predicted the size of the HH within 1 mm of the implanted head size showing very high accuracy. The center of rotation (COR) for the three-point method was within 1.34 mm of the (COR) of the articular surface. CONCLUSION: The three-point measuring technique using conventional radiographs may be useful to predict the HH size using extra-articular landmarks within a small margin of error. This method is simple, cost effective and has high level of precision. LEVEL OF EVIDENCE: Basic Science Study; Anatomic and Imaging Study.

Survey study suggests that reverse total shoulder arthroplasty is becoming the treatment of choice for four-part fractures of the humeral head in the elderly.

PURPOSE: The role of reverse total shoulder arthroplasty (RTSA) for three and four-part proximal humerus fractures is evolving. However, there does not appear to be a clear consensus amongst surgeons. The purpose of this study is to further define the standard of care, assessing surgeon preference and treatment considerations for management of such fractures. METHODS: Orthopaedic surgeons were surveyed on their training, practice setting, and experience regarding management of four-part proximal humerus fractures. The survey also presented five representative cases to assess treatment preferences. RESULTS: Two hundred five surgeons responded to the survey with fellowship training in shoulder and elbow surgery (114), orthopaedic trauma (35) or sports medicine/other training (56). There was no difference between respondents with years in practice and confidence with performing RTSA, however, surgeons in the academic setting were more confident in performing the surgery. Surgeons preferred RTSA for management of four-part fractures in patients over age 65. However, they also trended to favour hemiarthroplasty with higher co-morbidities. Physicians with more than 11 years of experience were more likely to choose hemiarthroplasty for older and high comorbidity patients. RTSA was not the preferred treatment method for younger, active patients. Patient age and fracture pattern had a greater influence on the surgeon's decision. CONCLUSIONS: There is a consensus in our study population that RTSA is the preferred treatment for four-part proximal humerus fractures for elderly patients with patient age and fracture pattern being the most important factors in making management decisions. LEVEL OF EVIDENCE: Level III - Case controlled study.

Can high-friction intraannular material increase screw pullout strength in osteoporotic bone?

BACKGROUND: Osteoporotic bone brings unique challenges to orthopaedic surgery, including a higher likelihood of problematic screw stripping in cancellous bone. Currently, there are limited options to satisfactorily repair stripped screws. Additionally, nonstripped screws hold with less purchase in osteoporotic bone. QUESTIONS/PURPOSES: This study attempts to answer the following questions: (1) Does high-friction intraannular (HFIA) augmentation increase pullout strength in osteoporotic and in severely osteoporotic bone; and (2) can HFIA repair stripped bone thread in osteoporotic and severely osteoporotic bone? METHODS: We measured screw pullout strength using a synthetic bone model in three groups: (1) predrilled nonstripped control holes as controls; (2) predrilled nonstripped augmented with HFIA; and (3) predrilled stripped holes repaired with HFIA. We tested this in osteoporotic and severely osteoporotic synthetic bone for a total of six test groups. We measured screw pullout force using an electromechanical tensile-testing machine comparing pullout force between the test groups and controls. RESULTS: HFIA augmentation did not increase pullout force compared with the control group in the osteoporotic bone model (489 ± 175 versus 607 ± 76, respectively; effect size = 0.94 [95% confidence interval {CI}, -1.75 to 0.08], p = 0.06). However, in severely osteoporotic cancellous bone that was augmented, the HFIA material generated more pullout force than the control (51 ± 18 versus 35 ± 16, respectively; effect size = 0.94 [95% CI, -0.02 to 1.82], p = 0.05). In stripped holes, HFIA partially restored pullout strength but remained weaker than controls in both osteoporotic and severely osteoporotic bone models (osteoporotic: 320 ± 59 versus 607 ± 76, respectively; effect size = -4.28 [95% CI, -5.57 to -2.51], p < 0.001; severely osteoporotic: 21 ± 8 versus 35 ± 16, respectively; effect size = -1.13 [95% CI, -2.0 to 0.12], p = 0.027). CONCLUSIONS: HFIA effectively augmented severely osteoporotic bone for screw purchase, but this effect was not seen for osteoporotic bone. In a model simulating both osteoporotic and severely osteoporotic bone, we found that HFIA can be used to repair stripped screw holes, but the resulting construct remains weaker than nonstripped controls. CLINICAL RELEVANCE: The HFIA material looks promising as a potential solution to stripped screws in osteoporotic bone. However, this material has yet to be tested in human bone. Furthermore, the fine mesh material could be damaged by autoclaving and could break off in vivo causing unknown tissue reactions. We recommend additional testing in a living animal model to better understand how living bone will react to the HFIA material.

National trends and perioperative outcomes in primary and revision total shoulder arthroplasty: Trends in total shoulder arthroplasty.

INTRODUCTION: Total shoulder arthroplasty (TSA) is a highly successful procedure for management of glenohumeral arthritis, fractures and rotator cuff tears. The purpose of this study was to evaluate patient demographics, perioperative outcomes and assess recent national trends in both primary and revision TSA. METHODS: The National Hospital Discharge Survey database was searched for patients admitted to US hospitals for primary and revision TSA from 2001 to 2010. RESULTS: A total of 1,297 patients who underwent primary TSA and 184 patients who underwent revision TSA were identified. The rates of primary TSA (r = 0.88) and revision TSA (r = 0.85) both demonstrated a strong positive correlation with time. The mean patient age of the primary group was significantly higher than the revision group. Gender was not significantly different between the groups. There was no significant difference in the racial make-up between the revision and primary groups. African Americans accounted for 3.3 % of primaries versus 4.3 % of revisions (p = 0.615). Revision TSA patients had a significantly longer average LOS (3.06 days vs 2.46 days, p < 0.01), more medical comorbidities (6.0 vs 5.1 comorbidities, p < 0.01) and a higher rate of developing a myocardial infarction (2.2 % versus 0 %, p < 0.01) than the primary TSA group. CONCLUSIONS: This study demonstrates that the rate of TSA is rapidly increasing in the US, with over a four-fold increase in revisions and five-fold increase in primaries over the ten years studied.

Arthroscopic femoral neck osteoplasty in slipped capital femoral epiphysis.

PURPOSE: To investigate the outcomes of arthroscopic femoral neck osteoplasty in patients with slipped capital femoral epiphysis (SCFE)-related impingement. METHODS: We retrospectively reviewed 37 consecutive patients (40 hips; 19 male and 18 female patients; age range, 10 to 19 years) with SCFE who underwent hip arthroscopy for femoral neck osteoplasty over a 4-year period. Six hips were excluded because of the severity of the slip or conversion to an open procedure. The preoperative and postoperative slip angle, alpha angle, and internal rotation in flexion were compared. Patients were evaluated for pain, functional limitations, and obligatory external rotation deformity (OERD) at each follow-up visit. The mean follow-up period was 22 months (range, 12 to 56 months). RESULTS: We analyzed the results of 34 hips. Adequate distraction could not be obtained initially in 7 hips. The labral and acetabular cartilage damage appeared to be from crushing and abrasion from the bony prominence of the neck. The goals of complete pain relief and correction of OERD were achieved in 88% of the hips. OERD and pain persisted in 2 hips, and 2 patients had residual pain despite good motion. There was a statistically significant improvement in alpha angle (from 88.22° and 56.91°, P < .0001) and internal rotation in flexion (from -21.53° to 10.28°, P < .0001) with intervention. CONCLUSIONS: Arthroscopic femoral neck osteoplasty is effective in decreasing pain, the alpha angle, and OERD in mild to moderate SCFE. Morbid obesity, scarring from previous surgery, and the presence of screws in the anterior neck presented challenges to the arthroscopic technique. LEVEL OF EVIDENCE: Level IV, therapeutic case series.

Radiographic assessment of prosthetic humeral head size after anatomic shoulder arthroplasty.

BACKGROUND: Restoring the premorbid proximal humeral anatomy during shoulder arthroplasty is critical yet can be difficult because of the deformity of the arthritic head. The purpose of this study was to measure the variation between surgeons and between types of prosthetics in reproducing the anatomic center of rotation (COR) of the humeral head after anatomic shoulder arthroplasty. METHODS: The anteroposterior radiographs of 125 stemmed and 43 resurfacing shoulder arthroplasties, performed by 5 experienced surgeons, were analyzed. All patients had primary replacement for treatment of end-stage glenohumeral arthritis. A best-fit circle to preserved nonarticular humeral landmarks was used to define the difference between the anatomic COR and the prosthetic COR. A difference in COR of >3.0 mm was considered clinically significant and analyzed for the cause of this deviation. RESULTS: The average deviation of the postoperative COR from the anatomic COR was 2.5 ± 1.6 mm for stemmed cases and 3.8 ± 2.1 mm for resurfacings. Thirty-nine stemmed cases (31.2%) and 28 resurfacings (65.1%) were beyond 3.0 mm of deviation and regarded as outliers. The majority of the stemmed outliers and all resurfacing outliers were overstuffed. An improper humeral head size selection and inadequate reaming were the main reasons for the deviation in stemmed and resurfacing outliers, respectively. CONCLUSION: A large percentage of shoulder replacements demonstrated significant deviations from an anatomic reconstruction. Resurfacing arthroplasty exhibited significantly greater deviations compared with stemmed arthroplasty (P < .001), indicating that surgeons have more difficulty in restoring the anatomy with resurfacings. Further studies are needed to assess the clinical impact of these deviations.

3D CT assessment of the relationship between humeral head alignment and glenoid retroversion in glenohumeral osteoarthritis.

BACKGROUND: Glenoid bone loss associated with advanced glenohumeral arthritis is frequently accompanied by subluxation of the humeral head with subsequent inferior outcomes of shoulder arthroplasty. We hypothesized that the relationship between the center of the humeral head and the perpendicular to the glenoid fossa plane differs from, and is independent of, the relationship between the center of the humeral head and the plane of the scapula. METHODS: Three-dimensional computed tomography (3D CT) imaging was performed on sixty patients with advanced osteoarthritis and fifteen controls with no osteoarthritis to define the baseline relationship between the center of the humeral head and the perpendicular to the glenoid fossa plane and the plane of the scapula. Correlations between these variables and the amount of bone loss and glenoid version were assessed. RESULTS: There was a strong linear relationship (p < 0.001) between glenoid retroversion and the center of the humeral head in relation to the center line of the scapula (humeral-scapular alignment). Humeral head alignment in relation to the glenoid plane (humeral-glenoid alignment) was variable and not strongly correlated with the amount of glenoid retroversion. The average glenoid retroversion for the normal shoulders was -3.5°, and the average humeral-scapular alignment offset percentage was -2.3%. The average humeral-glenoid alignment offset for the normal shoulders was 0.5 mm with an average humeral-glenoid alignment offset percentage of 0.9%. CONCLUSIONS: The location of the humeral head in relation to the glenoid can be defined as displacement from the plane of the scapula and from the perpendicular of the glenoid plane. These two measures are independent of one another. The data suggest that each measurement may represent a different effect on glenoid loading. CLINICAL RELEVANCE: The importance of this study is that it presents quantitative data and clear guidelines to define two measurements of glenohumeral alignment as separate and important variables. The clinical relevance of these methods will be further defined when they are correlated with clinical outcomes.

Determination of humeral head size in anatomic shoulder replacement for glenohumeral osteoarthritis.

BACKGROUND: We hypothesized that a sphere mapped to specific preserved nonarticular landmarks of the proximal humerus can accurately predict native humeral head radius of curvature (ROC) and head height (HH) in the osteoarthritic, deformed humeral head. METHODS: Three consistent nonarticular landmarks were defined with a 3-dimensional sphere (and 2-dimensional circle in midcoronal plane) placed along the articular surface in 31 normal cadaveric humeri. Side-to-side differences in ROC and HH were determined in 22 pairs of normal shoulders. Using the nonarticular landmarks and sphere method, 3 independent blinded observers performed 2 sets of measurements in 22 pairs of shoulders with unilateral glenohumeral osteoarthritis. The predicted native ROC and HH in the pathologic shoulder were compared with the normal side control. RESULTS: The mean side-to-side difference in normal shoulders was 0.2 mm (ROC) and 0.6 mm (HH). In the unilateral osteoarthritis cases, the intraobserver mean differences for the normal side were 0.3 mm (ROC) and 0.9 mm (HH). The pathologic side ROC and HH, defined by the sphere, exhibited intraobserver differences of 0.5 mm (ROC) and 1.0 mm (HH). The mean side-to-side differences between the normal and pathologic sides were 0.5 mm (ROC) with concordance correlation coefficient of 0.95 and 1.3 mm (HH) with concordance correlation coefficient of 0.66. CONCLUSION: A sphere mapped to preserved nonarticular bone landmarks can be used for accurate preoperative measurement of premorbid humeral head size and therefore the selection of an anatomically sized prosthetic head. This is applicable postoperatively, as is a circle method for 2-dimensional assessment of anatomic humeral reconstruction in the coronal plane.

Accuracy and reliability of postoperative radiographic measurements of glenoid anatomy and relationships in patients with total shoulder arthroplasty.

BACKGROUND: Radiographic imaging is the follow-up imaging modality most widely used for patients who have undergone total shoulder arthroplasty (TSA). However, its accuracy of measurement of component position has not been validated against a gold standard in a clinical series. METHODS: Thirty-two x-ray images and computed tomography scans were taken within 1 month of each other in patients who had undergone TSA with an all-polyethylene glenoid component. The humeral glenoid alignment in the coronal superior-inferior (SI) plane (HGA-SI), humeral glenoid alignment in the axial anterior-posterior (AP) plane (HGA-AP), and humeral scapular alignment in the axial plane (HSA-AP) were measured with 21 pairs of images, and glenoid component retroversion was measured with all 32 pairs. Intraclass correlation coefficients (ICC) were calculated for HGA-SI, HGA-AP, HSA-AP, and version, and accuracy analysis criteria of the radiographs were assessed using predetermined criterion. RESULTS: We found fair-moderate agreement between x-ray images and CT scans for HGA-SI (ICC = 0.42) and version (ICC = 0.69), but poor agreement for HGA-AP (ICC = 0.04) and HSA-AP (ICC = 0.38). An average difference of overestimating HGA-SI by 0.06% ± 7.7%, with a precision 95% confidence interval of 7.6%, and overestimating version by -4.2° ± 5.1°, with a precision 95% confidence interval of 9.9°, was found. CONCLUSION: This validation study has defined the ability and limitation for these measurements using high-quality axillary and AP radiographs.

Mid-term survivorship results for a rotating-platform knee prosthesis.

Interest in mobile-bearing knee prostheses is increasing in the US market. We studied results at 2 to 5 years with a mobile-bearing system that includes a cobalt-chrome tibial tray and femoral component with a polyethylene cruciate-retaining tibial component insert that allows rotation around a central axis and can be used with cruciate-retaining or posterior-stabilized femoral components. The inserts used in this study were cruciate retaining and did not include the posterior-stabilized design. The goal of this study was to demonstrate the function and safety of this prosthesis along with the lack of spinout, which is a major concern in the mobile-bearing knee. Four hundred thirty-five knees constituted the study cohort and underwent survivorship analysis and complication reporting. Routine clinic evaluations included pre- and postoperative radiographs and Knee Society knee and function scores at 6 and 12 weeks and every 2 years. The most recent follow-up data within 2 to 5 years was included for the study along with survey data. Flexion at most recent follow-up averaged 125°. Knee Society score at most recent visit averaged 88 of 100. Knee Society function score averaged 83 of 100. Radiographic results were available for 226 knees, with 97.3% assessed as normal and 6 with these issues: patella stress fracture (3), aseptic tibial loosening (1), patellar osteolysis (1), and patella aseptic loosening (1). In comparison with the fixed-bearing knee equivalent, this mobile-bearing knee demonstrated at least equivalent results in terms of survivorship, function, and patient satisfaction in the short- and mid-term.