Predictors of Recurrent Flexion Contracture after Total Knee Arthroplasty in Osteoarthritic Knees with Greater Than 15° Flexion Contracture

Background@#This study aimed to analyze the risk factors that predict recurrent flexion contracture (FC) after total knee arthroplasty (TKA) in osteoarthritic knees with FC ≥ 15°. @*Methods@#Data from a consecutive cohort comprising 237 TKAs in 187 patients with degenerative osteoarthritis, preoperative FC ≥ 15°, and a minimum follow-up period of 2 years were retrospectively reviewed. Preoperative FC was corrected intraoperatively from 0° to 5°. The incidence of recurrent FC (FC ≥ 10°) at 2 years postoperatively was investigated. Potential risk factors predicting recurrent FC including age, sex, body mass index, unilateral TKA, severity of preoperative FC, 3-month postoperative residual FC, γ angle, change in posterior femoral offset ratio, and lumbar degenerative kyphosis (LDK) were analyzed using logistic regression analysis. The post-hoc powers for the identified factors were then determined. @*Results@#Forty-one knees (17.3%) with recurrent FC were identified. Risk factors with sufficient power for recurrent FC were unilateral TKA, severity of preoperative FC, residual FC at 3 months postoperatively, and LDK (odds ratios of 3.579, 1.115, 1.274, and 3.096, respectively; p < 0.05; power ≥ 86.1). @*Conclusions@#Recurrent FC can occur in TKAs with the risk factors including unilateral TKA, severe preoperative FC, residual FC at 3 months postoperative, and LDK despite appropriate intraoperative correction. Surgical strategies and rehabilitation protocols used in managing FC should be applied in TKA cases with risk factors for recurrent FC.

Infection and Instability Increasing the Risk of Patella Baja and Pseudo-Patella Baja after Revision Total Knee Arthroplasty

Background@#Patella baja with patellar tendon shortening due to traumatic or ischemic injury is a widely known complication after primary total knee arthroplasty (TKA). Pseudo-patella baja may arise from the elevation of the joint line after excessive distal femoral resection. The maintenance of original patellar height is important in revision TKA because postoperative patella baja and pseudo-patella baja can cause inferior biomechanical and clinical results. We investigated the incidence and risk factors of patella baja and pseudo-patella baja after revision TKA. @*Methods@#We retrospectively reviewed data for 180 revision TKAs. Patella baja was defined as a truly low-lying patella with an Insall-Salvati ratio (ISR) of < 0.8 and a Blackburne-Peel ratio (BPR) of < 0.54. Pseudo-patella baja was defined as a relatively lowlying patella compared to the joint line within the normal range of ISR and with a BPR of < 0.54. Clinically, the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and range of motion (ROM) were evaluated. Risk factors increasing the incidence of patella baja and pseudo-patella baja after revision TKA were evaluated using multiple regression analysis. @*Results@#Before revision TKA, 169 knees did not exhibit patella baja or pseudo-patella baja, while 9 knees showed patella baja and 2 knees exhibited pseudo-patella baja. At 2 years after revision TKAs, 25 knees (13.9%) showed patella baja and 23 knees (12.8%) exhibited pseudo-patella baja. Despite no differences in the postoperative WOMAC score between groups with and without patella baja and pseudo-patella baja, the postoperative ROM was significantly smaller in the group with patella baja (113.3°) or pseudo patella baja (110.5°) than in the normal group (122.0°). Infection as the cause of revision TKA increased the risk of patella baja (odds ratio, 10.958; p < 0.001), and instability increased the risk of pseudo-patella baja (odds ratio, 11.480; p < 0.001). @*Conclusions@#Infection and instability resulted in increases in the incidence of patella baja and pseudo-patella baja after revision TKA. Information about the risk factors of patella baja and pseudo-patella baja will help TKA surgeons plan the height of the patella after revision TKA and improve clinical outcomes.

Sensor-Assisted Total Knee Arthroplasty: A Narrative Review

Wireless intraoperative load sensors have been used to improve the quality of soft-tissue balancing during total knee arthroplasty (TKA). Recent studies using the sensors have demonstrated reductions in gap imbalance, as well as early improvement of patientreported clinical outcomes and low rates of arthrofibrosis. However, well-designed prospective studies are needed to determine whether the application of the sensor technology for TKA will have clinical benefits and improve the survival of prosthesis. Knowledge of the load-sensing technology (advantages and disadvantages, potential pitfalls, and future prediction) is crucial to apply this new TKA technique successfully. Herein, we conduct a narrative review of previous studies on this technique.

Comparison of Patellofemoral-Specific Clinical and Radiographic Results after Total Knee Arthroplasty Using a Patellofemoral Design-Modified Prosthesis and Its Predecessor

Background@#One recently developed total knee arthroplasty (TKA) prosthesis was designed to alter the patellofemoral geometry and optimize patellar tracking compared to its predecessor. Despite an expectation that the improved design would contribute to optimal patellofemoral compatibility, its effect has not been confirmed with patellofemoral-specific clinical scoring systems and radiographic parameters. Our purpose was to compare patellofemoral-specific clinical and radiographic results after TKA using a patellofemoral design-modified prosthesis and its predecessor. @*Methods@#The results of 200 TKAs with Attune (group A) were compared to those of 200 TKAs with PFC Sigma (group B). Clinically, the presence of anterior knee pain (AKP), patellar crepitation, and Kujala score were checked. Radiographically, anterior femoral offset (AFO), posterior femoral offset (PFO), position of patellar ridge, and patellar tilt and translation were compared. @*Results@#In group A, AKP and patellar crepitation occurred less frequently (AKP: 3% vs. 8%, p = 0.028; patellar crepitation: 2.5% vs. 9%, p = 0.005) and Kujala score was higher (81.8 vs. 77.9, p < 0.001), when compared to group B. The AFO decreased in group A postoperatively but increased in group B (–1.2 vs. 1.1 mm, p < 0.001). The change in PFO was smaller in group A than group B (–1.2 vs. –3.6 mm, p < 0.001). The change in patellar ridge after TKA was smaller in group A than group B (1.4% vs. 8.3%, p < 0.001).The postoperative patella of group A was more laterally tilted (5.9° vs. 2.2°, p < 0.001) and less laterally translated (0.9 vs. 2.6 mm, p < 0.001). The proportion of incompatible patella tilt angle (≥ ± 10°) was greater in group A than group B (21.7% vs. 4.5%, p < 0.001). @*Conclusions@#TKA using Attune provided better patellofemoral-specific clinical results and favorable radiographic parameters related with patellar ridge, AFO, and PFO than TKA using PFC Sigma did. However, the current prosthesis did not provide better radiographic patellar tracking, which might be due to the medial location of the patellar ridge.

Comparison of Patellofemoral-Specific Clinical and Radiographic Results after Total Knee Arthroplasty Using a Patellofemoral Design-Modified Prosthesis and Its Predecessor

Background@#One recently developed total knee arthroplasty (TKA) prosthesis was designed to alter the patellofemoral geometry and optimize patellar tracking compared to its predecessor. Despite an expectation that the improved design would contribute to optimal patellofemoral compatibility, its effect has not been confirmed with patellofemoral-specific clinical scoring systems and radiographic parameters. Our purpose was to compare patellofemoral-specific clinical and radiographic results after TKA using a patellofemoral design-modified prosthesis and its predecessor. @*Methods@#The results of 200 TKAs with Attune (group A) were compared to those of 200 TKAs with PFC Sigma (group B). Clinically, the presence of anterior knee pain (AKP), patellar crepitation, and Kujala score were checked. Radiographically, anterior femoral offset (AFO), posterior femoral offset (PFO), position of patellar ridge, and patellar tilt and translation were compared. @*Results@#In group A, AKP and patellar crepitation occurred less frequently (AKP: 3% vs. 8%, p = 0.028; patellar crepitation: 2.5% vs. 9%, p = 0.005) and Kujala score was higher (81.8 vs. 77.9, p < 0.001), when compared to group B. The AFO decreased in group A postoperatively but increased in group B (–1.2 vs. 1.1 mm, p < 0.001). The change in PFO was smaller in group A than group B (–1.2 vs. –3.6 mm, p < 0.001). The change in patellar ridge after TKA was smaller in group A than group B (1.4% vs. 8.3%, p < 0.001).The postoperative patella of group A was more laterally tilted (5.9° vs. 2.2°, p < 0.001) and less laterally translated (0.9 vs. 2.6 mm, p < 0.001). The proportion of incompatible patella tilt angle (≥ ± 10°) was greater in group A than group B (21.7% vs. 4.5%, p < 0.001). @*Conclusions@#TKA using Attune provided better patellofemoral-specific clinical results and favorable radiographic parameters related with patellar ridge, AFO, and PFO than TKA using PFC Sigma did. However, the current prosthesis did not provide better radiographic patellar tracking, which might be due to the medial location of the patellar ridge.

Mid-term lifetime survivals of octogenarians following primary and revision total knee arthroplasties were satisfactory: a retrospective single center study in contemporary period

Background@#As life expectancy increases, the number of octogenarians requiring primary and revision total knee arthroplasty (TKA) is increasing. Recently, primary TKA has become a common treatment option in octogenarians.However, surgeons may still be hesitant about performing revision TKA on octogenarians because of concern about risk and cost benefit. The purpose of this study was to investigate clinical outcomes, postoperative complications, and mid-term lifetime survival in octogenarians after primary and revision TKA. @*Materials and methods@#We retrospectively reviewed 231 primary TKAs and 41 revision TKAs performed on octogenarians between 2000 and 2016. The mean age of patients undergoing primary TKA was 81.9 years and that of patients undergoing revision TKA was 82.3 years (p = 0.310). The age-adjusted Charlson comorbidity index was higher in revision TKA (4.4 vs. 4.8, p = 0.003). The Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and range of motion (ROM) were evaluated. The incidence of postoperative complications (TKA-related, specific or systemic) and lifetime survival rate (endpoint death determined by telephone or mail communication with patient or family) were investigated. @*Results@#The WOMAC and ROM improved significantly after primary and revision TKA, although postoperative results were worse in the revision group (33.1 vs. 47.2; 128.9° vs. 113.6°; p< 0.001, respectively). There were no cases of aseptic or septic component failure in either group. One case of periprosthetic fracture was observed in the revision group (0% vs. 2.4%, p = 0.151), and three cases of deep vein thrombosis (DVT)/pulmonary thromboembolism (PTE) (one case of DVT and two cases of PTE) were observed in the primary group (1.3% vs. 0%, p = 1.000). The most common systemic complication in both groups was delirium (7.4% vs. 14.6%, p= 0.131). There were no differences between the two groups in the other systemic complication rates. The 5-year and 10-year lifetime survival rates were 87.2% and 62.9%, respectively, in primary TKA and 82.1% and 42.2%, respectively, in revision TKA (p = 0.017). @*Conclusions@#Both primary and revision TKA are viable options for octogenarians, based on the satisfactory clinical outcomes, TKA-related complication rates, and mid-term lifetime survival. Delirium needs to be managed appropriately as the most common systemic complication in both primary and revision TKA in octogenarians.

Mid-term lifetime survivals of octogenarians following primary and revision total knee arthroplasties were satisfactory: a retrospective single center study in contemporary period

Background@#As life expectancy increases, the number of octogenarians requiring primary and revision total knee arthroplasty (TKA) is increasing. Recently, primary TKA has become a common treatment option in octogenarians.However, surgeons may still be hesitant about performing revision TKA on octogenarians because of concern about risk and cost benefit. The purpose of this study was to investigate clinical outcomes, postoperative complications, and mid-term lifetime survival in octogenarians after primary and revision TKA. @*Materials and methods@#We retrospectively reviewed 231 primary TKAs and 41 revision TKAs performed on octogenarians between 2000 and 2016. The mean age of patients undergoing primary TKA was 81.9 years and that of patients undergoing revision TKA was 82.3 years (p = 0.310). The age-adjusted Charlson comorbidity index was higher in revision TKA (4.4 vs. 4.8, p = 0.003). The Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and range of motion (ROM) were evaluated. The incidence of postoperative complications (TKA-related, specific or systemic) and lifetime survival rate (endpoint death determined by telephone or mail communication with patient or family) were investigated. @*Results@#The WOMAC and ROM improved significantly after primary and revision TKA, although postoperative results were worse in the revision group (33.1 vs. 47.2; 128.9° vs. 113.6°; p< 0.001, respectively). There were no cases of aseptic or septic component failure in either group. One case of periprosthetic fracture was observed in the revision group (0% vs. 2.4%, p = 0.151), and three cases of deep vein thrombosis (DVT)/pulmonary thromboembolism (PTE) (one case of DVT and two cases of PTE) were observed in the primary group (1.3% vs. 0%, p = 1.000). The most common systemic complication in both groups was delirium (7.4% vs. 14.6%, p= 0.131). There were no differences between the two groups in the other systemic complication rates. The 5-year and 10-year lifetime survival rates were 87.2% and 62.9%, respectively, in primary TKA and 82.1% and 42.2%, respectively, in revision TKA (p = 0.017). @*Conclusions@#Both primary and revision TKA are viable options for octogenarians, based on the satisfactory clinical outcomes, TKA-related complication rates, and mid-term lifetime survival. Delirium needs to be managed appropriately as the most common systemic complication in both primary and revision TKA in octogenarians.

Snapping Knee due to a Femoral Osteochondroma after Total Knee Arthroplasty

A female patient who underwent total knee arthroplasty presented with a snapping sensation over the left knee at 10 years postoperatively. Initially, the bony mass was visible on the medial femoral condyle radiographically at 5 years postoperatively. The mass had enlarged over time and her symptoms were progressive. The mass was excised at postoperative 18 years and confirmed as an osteochondroma histopathologically. The patient’s symptoms have been completely resolved for 3-year follow-up after excision. LEVEL OF EVIDENCE: V

The influence of computer-assisted surgery experience on the accuracy and precision of the postoperative mechanical axis during computer-assisted lateral closing-wedge high tibial osteotomy

BACKGROUND@#There is debate regarding the influence of a surgeon's experience with computer-assisted surgery (CAS) on the postoperative mechanical axis (MA) in CAS-high tibial osteotomy. The purpose of the present study was to compare radiographic results between early and late cohorts of a consecutive series of patients to assess the influence of CAS experience on accuracy and precision of the postoperative MA during CAS lateral closing-wedge high tibial osteotomy (LCWHTO).@*MATERIALS AND METHODS@#Results from 140 CAS-LCWHTO operations were retrospectively reviewed. The first 70 cases, performed during the learning curve period for CAS between 2005 and 2009, were considered to be the “early cohort.” The subsequent 70 cases, performed with greater CAS experience after the completion of the learning curve between 2009 and 2014, were considered to be the “late cohort.” The target postoperative MA angle was valgus 3°. Pre- and postoperative MA angles were evaluated by navigation and radiographs. The proportion of postoperative MA inliers (≤ target angle ±3°) was investigated radiographically. The correlation between the navigation and radiographic measurements was analyzed.@*RESULTS@#The average postosteotomy MA angle on navigation was 3.4° in both cohorts. The average postoperative MA angle on radiographs was 1.0° in the early cohort and 2.2° in the late cohort (P = 0.003). Radiographically, the proportion of postoperative MA inliers was greater in the late cohort than in the early cohort (early versus late, 71.4% versus 90%; P = 0.011). The pre- and postoperative correlation between navigation and radiographic measurements was also stronger in the late cohort (early versus late; preoperative r = 0.558 versus 0.663; postoperative r = 0.310 versus 0.376).@*CONCLUSIONS@#Greater experience with CAS increased the accuracy and precision of postoperative MA alignment as well as the correlation between navigation and radiographic measurements. Caution should be taken during registration procedures to achieve accurate alignment correction in CAS-LCWHTO.

Long-Term Survival Analysis of Unicompartmental Knee Arthroplasty / 대한정형외과학회잡지

PURPOSE: This study evaluated the long term clinical and radiographic results and the survival rates of unicompartmental knee arthroplasty (UKA). In addition, the factors affecting the survival of the procedure were analyzed and the survival curve was compared according to the affecting factors. MATERIALS AND METHODS: Ninety-nine cases of UKA performed between December 1982 and January 1996 were involved: 10 cases with Modular II, 44 cases with Microloc, and 45 cases with Allegretto prostheses. The mean follow-up period was 16.5 years. Clinically, the hospital for special surgery (HSS) scoring system and the range of motion (ROM) were evaluated. Radiographically, the femorotibial angle (FTA) was measured. The survival rate was analyzed using the Kaplan–Meier method. Cox regression analysis was used to identify the factors affecting the survival according to age, sex, body mass index, preoperative diagnosis, and type of implant. The Kaplan–Meier survival curves were compared according to the factors affecting the survival of UKA. RESULTS: The overall average HSS score and ROM was 57.7 and 134.3° preoperatively, 92.7 and 138.4° at 1 year postoperatively, and 79.1 and 138.4° at the last follow-up (p<0.001, respectively). The overall average FTA was varus 0.8° preoperatively, valgus 4.1° at postoperative 2 weeks, and valgus 3.0° at the last follow-up. The overall 5-, 10-, 15- and 20-year survival rates were 91.8%, 82.9%, 71.0%, and 67.0%, respectively. The factors affecting the survival were the age and type of implant. The risk of the failure decreased with age (hazard ratio=0.933). The Microloc group was more hazardous than the other prostheses (hazard ratio=0.202, 0.430, respectively). The survival curve in the patients below 60 years of age was significantly lower than those of the patients over 60 years of age (p=0.003); the survival curve of the Microloc group was lower compared to the Modular II and Allegretto groups (p=0.025). CONCLUSION: The long-term clinical and radiographic results and survival of UKA using old fixed bearing prostheses were satisfactory. The selection of appropriate patient and prosthesis will be important for the long term survival of the UKA procedure.

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.

Intentionally Increased Flexion Angle of the Femoral Component in Mobile Bearing Unicompartmental Knee Arthroplasty

PURPOSE: The purpose of this study was to determine the results of mobile bearing unicompartmental knee arthroplasty (UKA) with an intentionally increased flexion angle of the femoral component in patients requiring high flexion. MATERIALS AND METHODS: We investigated 45 knees treated by UKA. Clinically, we measured the range of motion (ROM) and the American Knee Society (AKS) score preoperatively and at final follow-up and investigated complications. Radiologically, we measured the flexion angle of the femoral component, the posterior slope angle of the tibial component, the femorotibial angle and mechanical axis of the limb postoperatively. RESULTS: The ROM was increased from 123° preoperatively to 139° at the final follow-up. The AKS knee and function scores increased from 59 and 68, respectively, preoperatively to 94 and 96, respectively, at the final follow-up. The flexion angle of the femoral component was 9.1°, and the posterior slope angle of the tibial component was 8.6°. There was one case of bearing dislocation in the largest femoral flexion angle case. CONCLUSIONS: The results might reflect the positive effect of an increased flexion angle of the femoral component up to 10° on ROM in mobile bearing UKA, which would contribute to better quality of life after UKA especially in populations requiring deep knee flexion.

Noise around the Knee

Noise in the knee joint is a common symptom that often leads to outpatient clinic visits. However, there have been no previous review articles regarding noise around the knee despite its high prevalence. We will review the noise characteristics according to sound nature and onset as well as factors for differentiation between physiological and pathological noises. In addition, we will describe causes of the physiological and pathological noises and management of noise in the knee. An appropriate review of the characteristics of noise, its pathophysiology, and factors for differentiation between physiological and pathological noises can facilitate patient guidance. It is important to differentiate between physiological noise and pathologic noise. In most cases, noise after surgery is simply the perception of noise that had been present previously due to emotional concerns. Minor problems associated with surgery, such as postoperative noise, can decrease patient satisfaction, especially among patients with high expectations. Following surgical principles and providing accurate information about physiological noise can decrease the risk of both pathological noise and patient dissatisfaction. In total knee arthroplasty, every attempt should be made to avoid patellar crepitus and clunk by using modern prostheses with proper patellofemoral conformity and by avoiding surgical errors.

Comparison of Mechanical Axis and Dynamic Range Assessed with Weight Bearing Radiographs and Navigation System in Closed Wedge High Tibial Osteotomy

PURPOSE: To compare navigation and weight bearing radiographic measurements of mechanical axis (MA) before and after closed wedge high tibial osteotomy (HTO) and to evaluate post-osteotomy changes in MA assessed during application of external varus or valgus force. MATERIALS AND METHODS: Data from 30 consecutive patients (30 knees) who underwent computer-assisted closed-wedge HTO were prospectively analyzed. Pre- and postoperative weight bearing radiographic evaluation of MA was performed. Under navigation guidance, pre- and post-osteotomy MA values were measured in an unloaded position. Any change in the post-osteotomy MA in response to external varus or valgus force, which was named as dynamic range, was evaluated with the navigation system. The navigation and weight bearing radiographic measurements were compared. RESULTS: Although there was a positive correlation between navigation and radiographic measurements, the reliability of navigation measurements of coronal alignment was reduced after osteotomy and wedge closing. The mean post-osteotomy MA value measured with the navigation was 3.5°±0.8° valgus in an unloaded position. It was 1.3°±0.8° valgus under varus force and 5.8°±1.1° valgus under valgus force. The average dynamic range was >±2°. CONCLUSIONS: Potential differences between the postoperative MAs assessed by weight bearing radiographs and the navigation system in unloaded position should be considered during computer-assisted closed wedge HTO. Care should be taken to keep the dynamic range within the permissible range of alignment goal in HTO.

Pain Management and Anesthesia in Total Knee Arthroplasty

No abstract available.

Computer-Assisted Navigation in High Tibial Osteotomy

Computer-assisted navigation is used to improve the accuracy and precision of correction angles during high tibial osteotomy. Most studies have reported that this technique reduces the outliers of coronal alignment and unintended changes in the tibial posterior slope angle. However, more sophisticated studies are necessary to determine whether the technique will improve the clinical results and long-term survival rates. Knowledge of the navigation technology, surgical techniques and potential pitfalls, the clinical results of previous studies, and understanding of the advantages and limitations of the computer-assisted navigation are crucial to successful application of this new technique in high tibial osteotomy. Herein, we review the evidence concerning this technique from previous studies.

Does Cruciate-Retaining Total Knee Arthroplasty Show Better Quadriceps Recovery than Posterior-Stabilized Total Knee Arthroplasty? - Objective Measurement with a Dynamometer in 102 Knees

BACKGROUND: Cruciate-retaining (CR) prostheses have been considered to produce more physiologic femoral rollback, provide better proprioception, and result in better quadriceps recovery than posterior-stabilized (PS) prostheses after total knee arthroplasty (TKA). However, there are very few studies demonstrating these benefits in an objective manner. We investigated whether CR-TKA could result in (1) better quadriceps recovery; (2) a greater proportion of patients with beyond the preoperative level of recovery; and (3) better clinical outcomes than PS-TKA. METHODS: This was a prospective non-randomized comparative study on the results of CR-TKA and PS-TKA. CR prostheses were used in 51 knees and PS prostheses in 51 knees. Quadriceps force was measured with a dynamometer preoperatively and at postoperative 6 weeks, 3 months, and 6 months consecutively. The Knee Society score (KSS) and range of motion (ROM) were also evaluated. RESULTS: There were no differences between two groups in terms of the objective quadriceps force during the follow-up period. The proportion of patients with beyond the preoperative level of recovery was similar between groups. Moreover, the KSS and ROM were not significantly different between two groups. CONCLUSIONS: CR-TKA did not result in better quadriceps recovery than PS-TKA during the 6-month follow-up. In other words, PS-TKA could lead to comparable quadriceps recovery despite greater preoperative weaknesses such as more restricted ROM and more severe degenerative changes of the knee.

Conversion Total Knee Arthroplasty after Failed High Tibial Osteotomy

Clinical results of high tibial osteotomy (HTO) deteriorate over time despite the initial satisfactory results. Several knees may require a conversion to total knee arthroplasty (TKA) because of failure such as the progression of degenerative osteoarthritis and the loss of the correction angle. It is important to know the long-term survival rate and common reason of failure in HTO to inform patients of postoperative expectations before surgery and to prevent surgical errors during surgery. In addition, it has been reported that clinical and radiological results, revision rate, and complication rate were poorer than those in patients without a previous HTO. There are few review articles that describe why conversion TKA after HTO is surgically difficult and the results are poor. Surgeons have to avoid the various complications and surgical errors in this specific situation. We would like to present the considering factors and technical difficulties during conversion TKA after HTO with a review of the literature. We could conclude through the review that the correction of deformity, lower amount of tibial bone resection, and sufficient polyethylene insert thickness, restoration of the joint line height, and adequate ligament balancing can be helpful in overcoming the technical challenges encountered during TKA following HTO.

Changes in Femoral Posterior Condylar Offset, Tibial Posterior Slope Angle, and Joint Line Height after Cruciate-Retaining Total Knee Arthroplasty

PURPOSE: Changes in the femoral posterior condylar offset (PCO), tibial posterior slope angle (PSA), and joint line height (JLH) after cruciate-retaining total knee arthroplasty (CR-TKA) were evaluated to determine their influence on the flexion angle. MATERIALS AND METHODS: A total of 125 CR-TKAs performed on 110 patients were retrospectively reviewed. Pre- and postoperative PCO, PSA, and JLH were compared using correlation analysis. Independent factors affecting the postoperative flexion angle of the knee were analyzed. RESULTS: The PCO was 28.2+/-2.0 mm (range, 24.5 to 33.1 mm) preoperatively and 26.7+/-1.8 mm (range, 22.2 to 31.2 mm) postoperatively (r=0.807, p0.291). CONCLUSIONS: Although the PCO and JLH did not change significantly after CR-TKA, the PSA decreased by 5.5degrees with a small range of variation. Restoration of the PCO and JLH could promote optimization of knee flexion in spite of the decreased PSA after CR-TKA.