Various Types of Medial Tibial Bone Resorption after Total Knee Arthroplasty Using a Thick Cobalt Chromium Tibial Baseplate.

Recent literature has implicated a thick cobalt chromium baseplate as a potential source of stress shielding and medial tibial bone resorption after total knee arthroplasty (TKA) in a Western population. The purpose was to calculate the incidence of various types and severity of medial tibial bone resorption utilizing a novel classification system after TKA with a thick cobalt chromium baseplate in Asian patients. Five hundred TKAs using Attune prostheses with mean follow-up of 3.4 years were evaluated, using the prospective radiographic data. The mean age was 71.3 years. The preoperative mechanical axis was varus, 11.2 degrees. The type and severity of medial tibial bone resorption were categorized as type U (resorption under the tibial baseplate up to 50% [U1] or beyond 50% [U2] of medial tibial tray width), C (resorption around the penetrated cement under the baseplate), and M (resorption on the medial tibial cortex without extension to the baseplate). Bone resorption of medial proximal tibia was observed in 96 knees (19.2%). Types U1 and U2 were seen in 46 and 28 knees, respectively. Type C was observed in 12 knees and type M in 10 knees. The type U resorption group had significantly more preoperative varus deformity (varus 12.9 vs. 10.9 degrees, p = 0.017). Medial tibial bone resorption after TKAs using a thick cobalt chromium baseplate is not uncommon and has various locations, types, and severities. The medial tibial bone resorption might be related to various causes, including stress shielding, thermal necrosis from cement in the bony hole, and bony devascularization. The type-U resorption has to be closely observed in patients with preoperative severe varus deformity. This is a Level IV study.

Neurologic deficit after reverse total shoulder arthroplasty: correlation with distalization.

BACKGROUND: Neurologic problems after reverse total shoulder arthroplasty (RTSA) have been reported, but there are a lack of studies regarding which nerve(s) are damaged and the outcomes for the patients who had neurologic complications after RTSA. The purpose of this study was to assess the prevalence and outcomes of neurologic deficit after RTSA and to evaluate the correlation between nonanatomic rearrangement of the shoulder joint and neurologic complications after RTSA. We hypothesized that the neurologic deficit was associated with excessive distalization or lateralization of the humerus after RTSA. METHODS: RTSA was performed on 182 consecutive shoulders with cuff tear arthropathy. Comparative analysis was performed on 34 shoulders with (group 1) and 148 shoulders without (group 2) neurologic deficit. RESULTS: The mean follow-up period in the study was 58.5 months (range: 24-124). The mean age was 71.5 ± 7.7 years in group 1 and 73.1 ± 7.2 years in group 2. Neurologic deficit after RTSA was found in 34 shoulders (19%). The mean postoperative acromiohumeral distance was 34.1 ± 11.0 mm in group 1 and 29.4 ± 7.6 mm in group 2 (P = .015). Significant differences in terms of postoperative distalization of the humerus were seen between group 1 (24.5 ± 9.4 mm) and group 2 (20.5 ± 8.3 mm) (P = .009). The most common forms of neurologic deficit after RTSA were axillary nerve (41.2%) and radial nerve (15%) injuries. Thirty shoulders (88%) had neuropraxia, and 4 shoulders (12%) had axonotmesis. By conservative treatment, all patients with neurologic complications achieved complete recovery without any additional surgery; the mean recovery period was 7.4 months (range: 2-38 months). CONCLUSION: Neurologic deficit occurred in 19% of patients who underwent RTSA, and it was significantly correlated with humeral distalization after surgery. Axillary nerve was mostly involved, and all patients with neurologic deficit achieved complete recovery without any additional surgery.

Is Lateral Posterior Tibial Slope Correlated With Clinical Outcomes of Lateral Meniscus Allograft Transplantation?

PURPOSE: To investigate (1) the correlation between lateral posterior tibial slope (PTS) and clinical outcomes of lateral meniscus allograft transplantation (MAT) and (2) the difference of lateral PTS between the extrusion and nonextrusion groups or between the failure and nonfailure groups in lateral MAT. METHODS: Between January 2001 and February 2016, we retrospectively evaluated 61 patients (mean age, 29.1 ± 12.2 years) who underwent postoperative magnetic resonance imaging (MRI) and were followed for a minimum of 2 years after primary lateral MAT. The lateral PTS and graft extrusion in the coronal and sagittal planes were assessed by using MRI performed at 1 year postoperatively. Clinical scores and graft failure were evaluated at the last follow-up visit. The correlation between lateral PTS and clinical outcomes (clinical scores, graft extrusion) was analyzed. Lateral PTS was compared between the extrusion and nonextrusion groups and between the failure and nonfailure groups. RESULTS: Mean lateral PTS on MRI was 6.6° ± 3.1° (range, 0.8° to 15.7°). A significant correlation was not identified between lateral PTS and clinical outcomes (clinical scores, graft extrusion in the coronal and sagittal planes). A significant difference in lateral PTS was not identified between the extrusion and nonextrusion groups in the coronal (6.2° ± 2.5° vs 7.0° ± 3.4°, P = .400) and sagittal (anterior horn, 6.5° ± 2.3° vs 6.7° ± 3.7°, P = .988; posterior horn, 6.8° ± 3.5° vs 6.5° ± 2.7°, P = .771) planes. Moreover, a significant difference was not identified between the failure and nonfailure groups (7.5° ± 3.3° vs 6.4° ± 3.0°, P = .388). CONCLUSIONS: A significant correlation between lateral PTS and clinical or radiologic outcomes of lateral MAT was not identified. LEVEL OF EVIDENCE: Level IV, therapeutic case series with subgroup analysis.

Clinical outcomes and survival rate of autologous chondrocyte implantation with and without concomitant meniscus allograft transplantation: 10- to 15-year follow-up study.

PURPOSE: The purpose of this study was to compare the clinical outcomes and survival rate of autologous chondrocyte implantation (ACI) with or without concomitant meniscus allograft transplantation (MAT). METHODS: Patients who underwent ACI of the medial or lateral femoral condyle with or without concomitant MAT were retrospectively reviewed. There were 14 patients (mean age, 31.2 ± 9.9 years) who underwent isolated ACI and 19 patients who underwent ACI with concomitant MAT (mean age, 34.8 ± 8.4 years). The International Knee Documentation Committee (IKDC) subjective score, Lysholm score, Tegner activity score, and 10- to 15-year survival rate were compared between groups. RESULTS: All clinical scores showed significant improvement postoperatively in both groups. At final follow-up, the IKDC subjective score was superior in isolated ACI (75.8 ± 18.4) compared to ACI with MAT (61.0 ± 16.6, p = 0.024). The Lysholm score was also higher in isolated ACI (77.5 ± 19.1) than ACI with MAT (62.5 ± 18.1, p = 0.029). The Tegner activity score did not differ between treatments (isolated ACI, 5.3 ± 1.1; ACI with MAT, 4.5 ± 1.3; p = 0.072). The 15-year survival rate for isolated ACI was higher than that of ACI with concomitant MAT (69.6% vs 50.2%), but this difference was not statistically significant (p = 0.19). CONCLUSIONS: ACI with concomitant MAT did not restore clinical outcomes as much as isolated ACI. There was a trend for the long-term survival rate to be greater in isolated ACI than ACI with MAT. These results should be considered in planning for the treatment of focal chondral defect with meniscus deficiency. LEVEL OF STUDY: Retrospective comparative trial; level of evidence, 3.

Mid-term clinical and radiological results do not differ between fixed- and mobile-bearing total knee arthroplasty using titanium-nitride-coated posterior-stabilized prostheses: a prospective randomized controlled trial.

PURPOSE: This study was performed to prospectively compare the clinical and radiographic results between mobile-bearing (MB) and fixed-bearing (FB) TKAs using ceramic titanium nitride (TiN)-coated prostheses. METHODS: Seventy MB and 70 FB TKAs using TiN-coated prostheses (ACS®) were prospectively evaluated. There were no differences in demographic characteristics between the two groups. Clinically, the Knee Society knee and function scores, WOMAC, and range of motion (ROM) were compared. Considering the possibility of a kinematic change in the polyethylene (PE) insert and a decrease in ROM following MB TKA, serial changes in the ROM were also compared. The thickness of the PE insert was compared according to the size of the femoral component. Radiographically, the alignment and positions of the components were compared. RESULTS: There were no differences between the two groups in clinical scores or ROM (n.s.). The maximum flexion increased from 133.5° ± 8.3° to 137.6° ± 5.5° across all time points in the MB group. The serial maximum flexion angles did not differ between the two groups over time (n.s.). The average thickness of the PE insert was greater in the MB group (12.0 ± 1.9 vs. 11.2 ± 1.6 mm, respectively, p = 0.008), especially when a large femoral component was used (12.7 ± 1.9 vs. 11.0 ± 1.5 mm, p = 0.005). The pre- and postoperative mechanical axes and positions of the components did not differ between the two groups (n.s.). CONCLUSIONS: TiN-coated MB TKA showed no significant advantage over FB TKA. The selection of bearing design would be clinically insignificant when using the TiN-coated TKA prosthesis. LEVEL OF EVIDENCE: II.

An intraoperative load sensor did not improve the early postoperative results of posterior-stabilized TKA for osteoarthritis with varus deformities.

PURPOSE: In the present study, the early results of sensor-assisted versus manually balanced posterior-stabilized total knee arthroplasty (TKA) for osteoarthritis with varus deformities were prospectively compared. METHODS: Fifty patients undergoing sensor-assisted TKA (group S) and 50 patients receiving manually balanced TKA (group M) were prospectively compared. The groups did not differ in terms of demographics, preoperative clinical status, or severity of deformity. The knee and function scores (KS and FS), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and range of motion (ROM) were evaluated clinically. The mechanical axes and positions of components were assessed radiographically. In sensor-assisted TKA, the medial and lateral compartment loads were compared based on the patellar positions of inversion and eversion. RESULTS: There was no between-group difference in the postoperative KS or FS (n.s., respectively). The average postoperative WOMAC score was 17.0 in group S and 18.0 in group M (n.s.). The ROM was 131.2° in group S and 130.8° in group M (n.s.). Neither the postoperative alignment of the mechanical axis nor the component positioning differed between the groups (n.s.). In sensor-assisted TKA, the difference between the medial and lateral compartment loads was less than 15 lbs (6.8 kg) in each knee. The lateral compartment load increased after patellar eversion (p < 0.001). CONCLUSION: There are concerns about the cost-benefit ratio of the intraoperative load sensor, despite its advantage of more precisely assessing ligament balance without patellar eversion, which resulted in a smaller lateral gap. A long-term follow-up study with a large cohort is required. LEVEL OF EVIDENCE: II.

Comparison of Clinical Results and Risk of Patellar Injury between Attune and PFC Sigma Knee Systems.

PURPOSE: The purposes of this study were to compare clinical results after total knee arthroplasty (TKA) using the Attune and PFC Sigma knee designs and to investigate whether the use of the Attune prosthesis increased the risk of patellar injury in Asian patients. MATERIALS AND METHODS: Three hundred knees that underwent TKA using Attune (group A) were compared to 300 knees that underwent TKA using PFC Sigma (group B). The Knee Society Knee Score (KS) and Function Score (FS), and range of motion (ROM) were compared. The residual patellar thickness was compared to evaluate the risk of patellar injury. RESULTS: The postoperative KS and ROM of group A were better than those of group B (93.1 vs. 88.8, p＜0.001 and 131.4° vs. 129.0°, p=0.008, respectively). The postoperative FS did not differ significantly between the two groups (80.9 vs. 78.7, p=0.427). The residual patella was thinner in group A (14.8 mm vs. 15.7 mm, p=0.003), which made up a higher proportion of the high-risk group for patellar fractures with a residual thickness of ＜12 mm (7.5% vs. 2.1%, p=0.003). CONCLUSIONS: TKA using the Attune prosthesis provided more favorable clinical results than TKA using PFC Sigma. However, the risk of injury in the residual patella was increased with use of the Attune prosthesis in Asian patients.

Stem Fixation in Revision Total Knee Arthroplasty: Indications, Stem Dimensions, and Fixation Methods.

Although stems improve initial mechanical stability in revision total knee arthroplasty (TKA), ideal indications, proper lengths and diameters, and appropriate fixation methods remain controversial. The topics of the present article include the indications, selection of lengths and diameters, and fixation methods of stems in revision TKA. The use of a stem in revision TKA can protect the juxta-articular bone. A stem cannot be a substitute for optimal component fixation; it plays an adjunctive role in transferring the loads from the compromised metaphysis to the stronger diaphysis. Proper bone surface preparation and appropriate use of the stem based on a great store of knowledge are required to support the stemmed components effectively in revision TKA. The balance between overshielding and overloading the juxta-articular bone would provide excellent structural protection. The stem length and diameter should be tailored according to patients' anatomical characteristics and determined fixation strategy. There are two traditional methods of stem fixation including the total cementation technique and the hybrid technique with a cementless press-fit stem. Selection of a cementation technique should be based on thorough consideration of advantages and disadvantages of each technique.

Comparison of Clinical Results and Injury Risk of Posterior Tibial Cortex Between Attune and Press Fit Condylar Sigma Knee Systems.

BACKGROUND: We compared clinical and radiographic results after total knee arthroplasty (TKA) using Attune and Press Fit Condylar Sigma, and investigated whether use of the current prosthesis increased injury risk to the tibial cortex in Asian patients. We also assessed whether a preoperative posterior tibial slope angle (PSA) is associated with the injury when using the current prosthesis. METHODS: The 300 TKAs with Attune (group A) were compared to the 300 TKAs with Press Fit Condylar Sigma (group B). Demographics were not different, except follow-up periods (24.8 vs 33.3 months, P < .001). The Western Ontario and McMaster Universities Index and range of motion were compared. A minimum distance between tibial component stem and posterior tibial cortex (mDSC) was compared. The correlation between preoperative PSA and mDSC was analyzed in group A. RESULTS: The postoperative Western Ontario and McMaster Universities Index and range of motion of group A were better than those of group B (17.7 vs 18.8, P = .004; 131.4° vs 129.0°, P = .008). The mDSC was shorter in group A (6.3 vs 7.0 mm, P < .001), which made up a higher proportion of the high-risk group for posterior tibial cortical injury with an mDSC of <4 mm (20.0% vs 10.7%, P = .002). A negative correlation was found between the preoperative PSA and mDSC in group A (r = -0.205, P < .001). CONCLUSION: The TKA using the current prosthesis provided more satisfactory results than the TKA using the previous prosthesis. However, the injury risk to the posterior tibial cortex increased in the knees with a large PSA when using the current prosthesis for Asian patients.