Posterior-stabilized Prosthesis Research Articles

Similar Midterm Outcomes of Total Knee Arthroplasties with Anterior and Posterior Tibial Slopes Performed on Paired Knees at a Minimum Follow-up of 5 Years.

A small posterior tibial slope (PTS) is generally recommended in posterior stabilized (PS) total knee arthroplasty (TKA). An unwanted anterior tibial slope (ATS), which can affect postoperative results, may be created in PS TKA because of the inaccuracy of surgical instruments and techniques, as well as high interpatient variability. We compared midterm clinical and radiographic results of PS TKAs with ATS and PTS performed on paired knees using the same prosthesis. One-hundred-twenty-four patients who underwent TKAs with ATS and PTS on paired knees using ATTUNE posterior-stabilized prostheses were retrospectively reviewed after a minimum follow-up period of 5 years. The mean follow-up period was 5.4 years. The Knee Society Knee and Function scores, Western Ontario and McMaster Universities Osteoarthritis Index, Feller and Kujalar scores, and range of motion (ROM) were evaluated. The preferred TKA out of ATS and PTS was also investigated. The hip-knee-ankle angle, component positions, tibial slope, posterior femoral offset, Insall-Salvati ratio, and knee sagittal angle were measured by radiography. There were no significant differences in the clinical results, including ROM, between TKAs with ATS and PTS preoperatively and at the last follow-up. Regarding patient preference, 58 patients (46.8%) were satisfied with bilateral knees, 30 (24.2%) preferred knees with ATS, and 36 (29%) preferred knees with PTS. There was no significant difference in the rate of preference between TKAs with ATS and PTS (p = 0.539). Except for the postoperative tibial slope (-1.8 vs. 2.5 degrees, p < 0.001), there were also no significant differences in the radiographic results, including the knee sagittal angle, preoperatively and at the last follow-up. The midterm outcomes were similar between PS TKAs with ATS and PTS performed on paired knees at a minimum of 5 years of follow-up. Nonsevere ATS did not affect midterm outcomes in PS TKA with proper soft tissue balancing and the current prosthesis of improved design. However, a long-term follow-up study is required to confirm the safety of nonsevere ATS in PS TKA. LEVEL OF EVIDENCE:: III.

Value of personalized osteotomy in primary total knee arthroplasty for severe varus knee osteoarthritis

To explore application value and efficacy of personalized osteotomy in primary total knee arthroplasty (TKA) for severe varus knee osteoarthritis. From June 2018 to January 2020, 36 patients (49 knees) with severe varus knee osteoarthritis were treated, including 15 males (21 knees) and 21 females (28 knees), aged from 59 to 82 years old with an average of (67.6 ± 6.5) years old;the course of disease ranged from 9.5 to 20.5 years with an average of (15.0 ± 5.0) years;11 patients (15 knees) with Kellgren-Lawrence grade Ⅲ and 25 patients (34 knees) with grade Ⅳ according to Kellgren-Lawrence grading. According to AORI clsssification of tibial bone defects, 8 patients (15 knees) were typeⅠTa and 16 patients (18 knees) were typeⅡ T2a. All patients' femor-tibial angle (FTA) was above 15°, and received primary TKA with personalized osteotomy. Thirty-three patients (45 knees) were treated with posterior-stabilized (PS) prostheses, 13 patients (15 knees) with PS prostheses combined with a metal pad and extension rod on the tibial side, and 3 patients (4 knees) with legacy constrained condylar knee (LCCK) prostheses. FTA, posterior condylar angle (PCA), medial proximal tibial angle (MPTA) and lateral distal femoral angle (LDFA) before and after operation at 1 month were measured and compared by using picture archiving and communication systems (PACS). Recovery of lower limbs before and after operation at 12 months was evaluated by American Knee Society Score(KSS), and complications were observed and recorded. All 36 patients (49 knees) were followed up from 15 to 40 months with an average of (23.46±7.65) months. FTA, MPTA were corrected from preoperative (18.65±4.28)° and (83.75±3.65)° to postoperative (2.35±1.46)° and (88.85±2.25)° at 1 month, respectively (P<0.001). PCA was decreased from (2.42±2.16)° before operation to (1.65±1.35)° at 1 month after operation, LDFA improved from (89.56 ± 3.55)° before operation to (91.63±3.38)° at 1 month after operation (P<0.05). KSS increased from (67.58±24.16) before opertion to(171.31±15.24) at 12 months after operation, 14 patients (19 knees) got excellent result, 19 (26 knees) good, and 3 (4 knees) fair. Personalized osteotomy is helpful for recovery of axial alignment of lower limbs and correct placement of prosthesis, could effectively relieve pain of knee joint, recover knee joint function.

Chronological Changes in Gait Oscillation in Patients after Total Knee Arthroplasty

Background: Pain and knee function improve immediately following total knee arthroplasty (TKA). However, immediate improvements in gait oscillation are not observed following TKA. This analysis aimed to chronologically assess changes in gait oscillation during walking in post-TKA patients. Methods: Twenty patients who were diagnosed with knee osteoarthritis underwent unilateral TKA. A Bi-Surface posterior-stabilized (PS) prosthesis with cementation was used for all patients. Acceleration (anterior, vertical, TKA side -, and -contralateral side directions) was examined during walking. A preoperative analysis was performed followed by postoperative analyses at 3, 6, 9, and 12 months. Results: Acceleration in the anterior direction and the sacral region tended to increase until 6 months post-TKA, but remained largely unchanged thereafter. In the dorsal vertebral region, acceleration to the anterior direction trended to decrease over time. Additionally, acceleration in the TKA-side direction in the sacral and dorsal vertebral region also tended to decrease over time. The post-TKA sacral-dorsal vertebral ratio in the TKA-side direction tended to increase over time, and the values on the contralateral side direction tended to increase for up to 6 months; however, there was no significant change thereafter. Conclusion: Acceleration in the anterior and lateral directions (TKA side) may improve chronologically after TKA, and gait may be performed mainly on the pelvic girdle during the postoperative course of TKA.

Similar survival rate but lower functional outcomes following TKA in the elderly people compared to younger patients: analysis of a posterior stabilised implant with minimum 5-year follow-up.

Literature regarding outcomes in patients over 80years old after total knee arthroplasty (TKA) is inconsistent. We aimed to compare implant survivorship and functional outcomes between elderly patients (≥ 80years) and younger patients (< 80years) following TKA, using a single modern posterior-stabilized (PS) prosthetic design. This is a retrospective cohort study of 80 patients over 80years old who underwent TKA between January 2015 and December 2016, who were compared with younger patients (60-75years old) operated during the same period. Patients were matched with a ratio of 1:3 based on logistic regression analysis of gender and body mass index. All patients received the same cemented PS prosthesis with a fixed bearing polyethylene insert, with or without patellar resurfacing. Implant survival and patient-reported outcome measurements were compared between the two groups. At last follow-up, data were available for 41 knees in the elderly group (including 17 patients who died before 5-year follow-up) and 123 knees in the younger group. Functional results were better at final follow-up in the group < 80years with a significantly higher Knee Society Function Subscore (88.6 ± 16.9 vs 79.4 ± 22.1, p < 0.01), but no significant differences in Knee Subscore and global Knee Society Score (p > 0.05), nor regarding maximum flexion (121° ± 12 and 117° ± 13, p = 0.08). The implant survivorship was 100.0% after a mean 64.4-month follow-up (range 60-78), without revision requiring removal of the implant in any group. The survival rate without any reoperation was 97.6% (95% CI 93.0-100.0) in the elderly group and 95.9% (95% CI 92.5-99.5) in the younger group (p = 0.64). At a minimum of 5-year follow-up, there was no revision surgery and a very low rate of complications requiring reoperations both in the group over 80years of age and in the younger population, with the use of a PS prosthesis. The functional results were slightly lower for elderly patients and correlate with the lower functional demands of this population. The indication for TKA, especially with a PS implant, may be encouraged in appropriately selected elderly patients. III (retrospective cohort study).

Bicruciate-retaining total knee arthroplasty non-inferior to posterior-stabilized prostheses after 5years: a randomized, controlled trial.

Bicruciate-retaining (BCR) prostheses may improve satisfaction of patient undergoing total knee arthroplasty (TKA). The objective of this randomized controlled trial was to assess whether BCR prostheses provide better clinical outcomes than posterior-stabilized (PS) prostheses. This is a randomized single-blind control trial involving a total of 77 patients with knee osteoarthritis, randomly assigned to undergo TKA with a BCR or PS implant between 2015 and 2019. Mean follow-up period was 39months. Clinical and demographic data were extracted manually from medical records. Data acquisition included patient demographics, knee range of motion, and patient-reported outcomes via KSS, KOOS, WOMAC, and SF-12 scores. A total of 38 patients were randomized to the PS group and 39 to the BCR group. At the 5-year follow-up, no statistical differences were noted for knee range of motion or patient-reported outcomes between the two groups, except for a greater knee flexion in the early follow-up period in the PS group. Five adverse events occurred in the BCR group compared to none in the PS group (p = 0.02). BCR TKA yield similar clinical and patient-reported outcomes 5 years following the intervention compared with PS TKA. The BCR TKA had more complications. I (Randomized Controlled Trial).

Medial osteophyte resection width correlates with correction of the medio-lateral component gap imbalance during posterior-stabilized total knee arthroplasty

BackgroundThere is a lack of robust evidence for a correlation between the medial osteophyte resection and correction of the medio-lateral gap imbalance during total knee arthroplasty. The purpose of the present study was to quantify the effect of osteophyte resection on the medio-lateral component gap imbalance during posterior-stabilized total knee arthroplasty. MethodsForty-five cases of primary posterior-stabilized total knee arthroplasty using the measured resection technique with posterior-stabilized prosthesis for varus knee osteoarthritis were reviewed. Medial and lateral joint gaps at 0°, 10°, 45°, and 90° of flexion, and maximum flexion were measured intraoperatively before and after the osteophyte resection. The relationship between medial osteophyte resection width and change of joint varus angle and medial component gap were assessed using Pearson's correlation coefficient. FindingsMedial component gap and joint varus angle values at post medial osteophyte resection were significantly larger and lower than at pre-resection (Medial gap: pre 9.5 ± 1.8 mm, post 10.3 ± 1.8 mm, P < 0.001, Joint angle: pre 5.2 ± 2.9°, post 4.2 ± 2.9°, P < 0.001). There was no significant difference between pre and post medial osteophyte resection in lateral component gaps. Per each 1 mm of medial osteophyte resection width, increases of 0.13 mm medial component gap and 0.2° valgus were observed (Medial gap: r = 0.38, P < 0.001, Joint angle: r = 0.38, P < 0.001). InterpretationMedial osteophyte resection increases the medial component gap without lateral component gap increase, while decreasing the joint varus angle in primary posterior-stabilized total knee arthroplasty for varus knee osteoarthritis. Osteophyte resection width was found to correlate with correction of the medio-lateral component gap imbalance.

Anterior Knee Pain Following Primary Unilateral Total Knee Arthroplasty With Posterior-Stabilized Prosthesis and Patellar Resurfacing: Prevalence and Clinical Implications

BackgroundAnterior knee pain following total knee arthroplasty (TKA) is associated with patient dissatisfaction. Factors related to postoperative anterior knee pain and its impact on patient outcomes are poorly understood. The following are the aims of this study: (1) to report the prevalence of anterior knee pain before and after TKA using a posterior-stabilized prosthesis with routine patellar resurfacing; (2) to investigate the association of preoperative clinical factors with the presence of anterior knee pain after TKA; and (3) to explore the association of postoperative anterior knee pain with postoperative self-reported function and quality of life. MethodsThis retrospective study included 506 patients who had undergone elective primary unilateral TKA with a posterior-stabilized prosthesis and patellar resurfacing. Outcome measures prior to and 12 months after TKA included self-reported anterior knee pain, knee function, and quality of life. ResultsPrevalence of anterior knee pain was 72% prior to and 15% following TKA. Patients who had preoperative anterior knee pain had twice the risk of experiencing anterior knee pain after TKA than patients who did not have preoperative anterior knee pain (risk ratio: 2.37, 95% CI 1.73-2.96). Greater severity of preoperative anterior knee pain and worse self-reported function were associated with the presence of postoperative anterior knee pain (rho = 0.15, P < .01; rho = 0.13, P < .01, respectively). Preoperative age, gender, and quality of life were not associated with postoperative anterior knee pain. Greater severity of postoperative anterior knee pain was associated with worse knee function at 12 months postoperative (rho = 0.49, P < .01). ConclusionOne in 7 patients reported anterior knee pain 12 months following posterior-stabilized and patella-resurfaced TKA. The presence of preoperative anterior knee pain and worse self-reported function are associated with postoperative anterior knee pain.

Moderate External Rotation of Tibial Component Generates More Natural Kinematics Than Internal Rotation After Total Knee Arthroplasty.

This study aimed to investigate the influence of tibial malrotation on knee kinematics after total knee arthroplasty (TKA). A symmetric fixed-bearing posterior-stabilized prosthesis was implanted in the validated knee model with different rotational alignments of the tibial component (neutral, 3° external rotation, 5° external rotation, 3° internal rotation, and 5° internal rotation). Computational kinematic simulations were used to evaluate the postoperative kinematics of the knee joint including anteroposterior translation femoral condyles and axial rotation of tibial component during 0°–135° knee flexion. The results revealed that the neutral position of the tibial component was not the closest kinematics to the intact knee, the model with 5° external rotation of the tibial component showed the closest lateral condyle translation and tibial axial rotation, and moderate external rotation could improve the kinematics after TKA.

Comparative outcomes between a new robotically assisted and a manual technique for total knee arthroplasty in patients with osteoarthritis: a prospective matched comparative cohort study.

Studies comparing clinical outcomes between manual (mTKA) and robotic-assisted TKA (raTKA) are limited. This prospective comparative cohort study aimed to compare early postoperative outcomes, satisfaction, and patient-reported outcome measures (PROMS) between patients undergoing mTKA and ROSA raTKA (Zimmer Biomet, Warsaw, IN) performed by one surgeon. Thirty ROSA raTKAs and 30 mTKAs performed by one surgeon during 2020-2021 were prospectively evaluated. Groups were matched for age, sex, and body mass index. All procedures were primary unilateral TKAs using the same posterior-stabilized prosthesis (Nexgen Legacy, Zimmer Biomet, Warsaw, IN). Length of hospital stay (LOS) and blood transfusion rate were recorded. Complications, visual analogue scale score (VAS), and Oxford Knee Score (OKS) were assessed preoperatively and for six postoperative months. The Forgotten Joint Score (FJS) and patient satisfaction were evaluated 6months postoperatively. No complications and similar blood transfusion rate were recorded between groups (p = 0.228). The LOS was non-significantly shorter in raTKA than in the mTKA group (p = 0.120). Mean preoperative and third-month OKS and VAS scores were comparable between groups. However, the mean 6-month OKS (p = 0.006) and VAS score (p = 0.025) were significantly better for the raTKA group. The 6-month FJS was significantly greater for raTKA than the mTKA group (p< 0.001). One patient was unhappy in raTKA, and three in the mTKA group (p = 0.301). Significantly more raTKA patients answered that they would undergo surgery again (p = 0.038). raTKA was associated with the same complication risk, less pain level, better patient satisfaction, and PROMs on 6-month follow-up than the mTKA group.

Similar outcomes including maximum knee flexion between mobile bearing condylar-stabilised and fixed bearing posterior-stabilised prosthesis: a case control study

PurposeProsthesis design influences stability in total knee arthroplasty and may affect maximum knee flexion. Posterior-stabilised (PS) and condylar-stabilised (CS) designed prosthesis do not require a posterior-cruciate ligament to provide stability. The aim of the current study was to compare the range of motion (ROM) and clinical outcomes of patients undergoing cemented total knee arthroplasty (TKA) using either a PS or CS design prosthesis.MethodsA total of 167 consecutive primary TKAs with a CS bearing (mobile deep-dish polyethylene) were retrospectively identified and compared to 332 primary TKA with a PS constraint, with similar design components from the same manufacturer. Passive ROM was assessed at last follow-up with use of a handheld goniometer. Clinical scores were assessed using Patient-Reported Outcome Measures (PROMs); International Knee Society (IKS) knee and function scores and satisfaction score. Radiographic assessment was performed pre and post operatively consisting of mechanical femorotibial angle (mFTA), femoral and tibial mechanical angles measured medially (FMA and TMA, respectively) on long leg radiographs, tibial slope and patella height as measured by the Blackburne-Peel index (BPI).ResultsBoth groups had a mean follow-up of 3 years (range 2–3.7 years). Mean post-operative maximum knee flexion was 117° ± 4.9° in the PS group and 119° ± 5.2° in the CS group (p = 0.29). Postoperative IKS scores were significantly improved in both groups compared to preoperative scores (p < 0.01). The mean IKS score in the PS group was 170.9 ± 24.1 compared to 170.3 ± 22.5 in the CS group (p = 0.3). Both groups had similar radiographic outcomes as determined by coronal and sagittal alignment, tibial slope and posterior condylar offset ratio measurements. When considering the size of tibial slope change and posterior-condylar offset ratio, there was no differences between groups (p = 0.4 and 0.59 respectively). The PS group had more interventions for post-operative stiffness (arthrolysis or manipulation under anaesthesia) 8 (2.7%) compared to 1 (0.6%) in the CS group (p = 0.17).ConclusionCondylar-stabilised TKA have similar patient outcomes and ROM at a mean follow-up of 3 years compared to PS TKA. Highly congruent inserts could be used without compromising results in TKA at short term.Level of evidenceLevel IV, retrospective case control study.

Fixed-Bearing Posterior-Stabilized Implant versus Constrained Condylar Knee in One-Stage Bilateral Primary Arthroplasty of the Varus Knee: A Randomized Controlled Trial with Minimum 2-year Follow-Up.

Background:Severe varus deformity of the knee poses a technical challenge in balancing the flexion–extension gaps. The use of a varus–valgus constrained prosthesis is a solution to achieve coronal plane stability. The results of constrained condylar knee (CCK) implants in primary total knee arthroplasty are not well known. This study aims to compare the functional outcomes of posterior-stabilized (PS) and CCK implants for primary arthroplasty of the varus knee.Materials and Methods:Twenty patients with bilateral severe osteoarthritis and genu varum of more than 10° were enrolled in this study. One knee was randomly implanted with a fixed-bearing PS implant, whereas the other was implanted with a CCK prosthesis. Pre- and postoperative Knee Society Score (KSS) and Oxford Knee Score (OKS) questionnaires were completed, and knee flexion was measured and compared.Results:The patients were followed for 32 months on average (24–36 months). On the KSS and OKS, both the groups improved significantly, but the difference between them was not statistically significant. Postoperative knee flexion was also not different between the two groups. Furthermore, 18 patients could not distinguish the difference between the two prostheses, whereas two patients preferred the PS one.Conclusion:We demonstrated that a PS prosthesis can achieve comparable functional results to the CCK one in the short term.

Appropriate determination of the surgical transepicondylar axis can be achieved following distal femur resection in navigation-assisted total knee arthroplasty

BackgroundMany surgeons have determined the surgical transepicondylar axis (sTEA) after distal femur resection in total knee arthroplasty (TKA). However, in most navigation systems, the registration of the sTEA precedes the distal femur resection. This sequential difference can influence the accuracy of intraoperative determination for sTEA when considering the proximal location of the anatomical references for sTEA and the arthritic environment. We compared the accuracy and precision in determinations of the sTEA between before and after distal femur resection during navigation-assisted TKA.MethodsNinety TKAs with Attune posterior-stabilized prostheses were performed under imageless navigation. The sTEA was registered before distal femur resection, then reassessed and adjusted after distal resection. The femoral component was implanted finally according to the sTEA determined after distal femur resection. Computed tomography (CT) was performed postoperatively to analyze the true sTEA (the line connecting the tip of the lateral femoral epicondyle to the lowest point of the medial femoral epicondylar sulcus on axial CT images) and femoral component rotation (FCR) axis. The FCR angle after distal femur resection (FCRA-aR) was defined as the angle between the FCR axis and true sTEA on CT images. The FCR angle before distal resection (FCRA-bR) could be presumed to be the value of FCRA-aR minus the difference between the intraoperatively determined sTEAs before and after distal resection as indicated by the navigation system. It was considered that the FCRA-bR or FCRA-aR represented the differences between the sTEA determined before or after distal femur resection and the true sTEA, respectively.ResultsThe FCRA-bR was −1.3 ± 2.4° and FCRA-aR was 0.3 ± 1.7° (p < 0.001). The range of FCRA-bR was from −6.6° to 4.1° and that of FCRA-aR was from −2.7° to 3.3°. The proportion of appropriate FCRA (≤ ±3°) was significantly higher after distal femur resection than that before resection (91.1% versus 70%; p < 0.001).ConclusionsThe FCR was more appropriate when the sTEA was determined after distal femur resection than before resection in navigation-assisted TKA. The reassessment and adjusted registration of sTEA after distal femur resection could improve the rotational alignment of the femoral component in navigation-assisted TKA.Level of evidenceIV.

Similar outcomes to primary total knee arthroplasty achievable for aseptic revision using the same primary posterior-stabilised prosthesis at a mean follow-up of 49months.

The aim of the study was to compare clinical and radiological outcomes between primary and aseptic revision TKAs using the same posterior-stabilised (PS) prosthesis. The authors hypothesised similar outcomes between both groups for selected patients. This retrospective, case-control study assessed 36 patients who underwent aseptic revision TKA compared to a match group of 72 primary TKA. Both groups had the same PS design implant (ANATOMIC®, Amplitude, Valence, France). The International Knee Society (IKS) score, radiological outcomes (postoperative alignment, patellar tilt and radiolucent lines), re-intervention and revision rate were compared between the two groups with a minimum follow-up of 3 years. The final study cohort included 29 patients and 63 patients respectively in the revision and primary group, with a mean follow-up of 49.1months (range 36.1-69). Postoperatively, there was no significant difference in IKS scores between the two groups [169.8 for the revision group and 179.6 for the primary group (p = 0.09)]. No statistical difference was observed for post-operative satisfaction 86.2% versus 92.1% (p = 0.46). Between the two groups, there was no difference in mean radiological assessment, including radiolucent lines (p = 0.7). There was no significant difference for overall implant survivorship 96.5% versus 100% (p = 0.13) at 36months. Similar clinical, radiological and survivorship outcomes were found between rTKA and primary TKA groups using the same PS level of constraint in patients undergoing revision surgery for aseptic indications at 3-year follow-up. Use of PS implants in rTKA for the correct indication suggests this to be a safe approach at least in the medium term. IV, retrospective case-control study.

Consistent femoral external rotation during weight-bearing knee flexion is associated with better patient-reported pain and mediolateral balance after total knee arthroplasty

BackgroundNormal knees generally show consistent femoral external rotation during knee flexion, although knees that have had total knee arthroplasty exhibit various rotational patterns with less rotational angle. This study aimed to determine whether consistent femoral external rotation during weight-bearing knee flexion after total knee arthroplasty is associated with better patient-reported outcomes and mediolateral joint balance. MethodsA total of 40 total knee arthroplasty knees with a high-flexion posterior-stabilized prosthesis were divided into two groups based on their axial rotational kinematic pattern during squatting activity, and the clinical results including patient-reported outcomes and joint laxity were compared between the consistent external rotation group (20 knees) and the inconsistent external rotation group (20 knees). The unpaired Student's t-test or Welch's test were used for group comparison, and Fisher's exact test was applied for categorical data. Findings“Pain at rest” and “Pain at first gait in the morning” measured using a numerical rating scale (/10) were significantly lower in the consistent external rotation group compared with those in the inconsistent external rotation group. “Pain during gait on flat surface” tended to be lower in the consistent external rotation group. Medial stability was obtained in both groups with significantly greater lateral laxity in extension in the inconsistent external rotation group. InterpretationTotal knee arthroplasty knees with consistent femoral external rotation during weight-bearing knee flexion exhibited better patient-reported pain and mediolateral soft tissue balance. Surgical procedures that control the mediolateral balance with medial stability would induce consistent femoral external rotation and improve patient-reported pain.

Loss of Knee Flexion and Femoral Rollback of the Medial-Pivot and Posterior-Stabilized Total Knee Arthroplasty During Early-Stance of Walking in Chinese Patients

Background The medial-pivot (MP) prosthesis was developed to produce more physiological postoperative knee kinematics and better patient satisfaction than traditional prostheses, but outcomes are inconsistent in different studies of Caucasian patients. This study aimed to investigate the postoperative patient satisfaction and in vivo knee kinematics of the MP and posterior-stabilized (PS) prosthesis during gait activity in Chinese patients.Methods A retrospective analysis of 12 patients was received for this study in each MP group and PS group. Patient-reported satisfaction level and Forgotten Joint Score (FJS) were evaluated with questionnaires. A dual fluoroscopic imaging system was used to investigate in vivo knee kinematics of MP and PS total knee arthroplasty (TKA) during treadmill walking at a speed of 0.4 m/s.Results Comparable promising patient satisfaction and overall FJS (MP 60.7 ± 15.35 vs. PS 51.3 ± 17.62, p = 0.174) were found between the MP and PS groups. Peak flexion appeared at around 70% of gait cycle with values of 52.4 ± 7.4° for MP and 50.1 ± 3.6° for PS groups (no difference). Both groups maintained a stable position at the stance phase and began to translated anteriorly at toe-off with an amount of 4.5 ± 2.3 mm in the MP and 6.6 ± 2.7 mm in the PS (p = 0.08) group until late swing. The range of this external rotation motion was 5.9 ± 4.8 and 6.2 ± 4.1° (p = 0.79) for the MP and PS, respectively.Conclusion A similar knee kinematics pattern characterized by a loss of early-stance knee flexion and femoral rollback during walking was observed in the MP and PS TKAs. Our study confirmed similar effectiveness of MP TKA compared to PS TKA in Chinese patients, while the change of knee kinematics of both implants during slow walking should be noted.

Onlay Patellar Resurfacing in a Posterior-Stabilized Total Knee Arthroplasty Increases Patellar Crepitus Complication: A Randomized, Controlled Trial

BackgroundPatellar crepitus (PC) is a potentially problematic complication after total knee arthroplasty (TKA) more commonly occurring with a posterior-stabilized (PS) prosthesis. Patellar resurfacing has been reported to reduce PC complications; however, no study has compared the PC complication rates between 2 different resurfacing techniques, namely inlay and onlay. MethodsA prospective, randomized controlled trial was conducted to compare the PC complication between inlay and onlay patellar resurfacing techniques. A total of 222 patients who underwent unilateral TKA using a Legion PS Total Knee System were randomized into 2 groups. PC incidence, time of PC presentation, radiographic parameters associated with PC development, and clinical outcomes were evaluated at 3, 6, 9, 12, 18, and 24 months postoperatively. ResultsPC occurred significantly more in the onlay group (17.9% vs 6.5%, P = .009). Time of PC presentation in both groups was not different. Anterior knee pain was found in 11.5% of PC patients, and none required any surgical procedure. Postoperative radiographic parameters, range of motion, Knee Society score, Oxford score, patellar score, incidence and intensity of anterior knee pain, and visual analog scale of overall knee pain were not significantly different between the 2 groups during the follow-up period. ConclusionTo reduce the chance of PC development, we suggest an inlay patellar resurfacing technique during PS-TKA with this knee system.

Posterior cruciate-retaining versus posterior stabilized total knee arthroplasty

Background: Some surgeons decide to preserve or sacrifice PCL preoperatively based on their experience and training, while others decide intraoperatively after evaluating morphology of PCL, knee alignment, range of motion (ROM) and stability of knee. Several papers have been published comparing outcomes of PCL-retaining and PCL-stabilizing types of prostheses in neutrally aligned knees. Some potential advantages of cruciate-retaining prosthetic designs include preservation of bone, more normal knee kinematics, increased proprioception, femoral rollback on the tibia during flexion, and greater stabilization of the prosthesis, with the PCL preventing anterior translation of the femur on the tibia. Aim of the study: To compare posterior cruciate-retaining versus posterior stabilized total knee arthroplasty. Materials and methods: For the study, a total of 60 patients underwent total knee arthroplasty utilizing a posterior-stabilized prosthesis, and another group of 60 patients received a cruciate-retaining implant. All patients who had osteoarthritis, osteonecrosis, or rheumatoid arthritis and who were indicated for a total knee arthroplasty were invited to take part in a prospective study to follow their outcomes. The patients were evaluated in the office one month after the procedure and annually thereafter. The ranges of motion, Knee Society scores, radiographic outcomes, and complications were assessed at each follow-up visit, and these were compared at the five-year follow up. Results: We observed that the mean Knee Society knee scores of the Group 1 was 80 and for Group 2 was 75. The mean Knee Society functional scores were 67 points for Group 1 and 78 for Group 2. The mean ranges of motion were 132° for Group 1 and 125° for the for Group 2. The results on comparison were found to be statistically non-significant. Conclusion: Within the limitations of the present study, it can be concluded that posterior cruciate-retaining versus posterior stabilized total knee arthroplasty offers significant benefits postoperatively; however, on comparing both the procedures provide similar results.

Periprosthetic early insufficiency fracture after total knee arthroplasty: a retrospective case series

Background: Early periprosthetic insufficiency fracture after total knee arthroplasty (TKA) is a rare, yet serious debilitating condition. Identification of the risk factors predisposing patients to this fracture is crucial to reduce its incidence. We aimed to investigate if patients who experienced early periprosthetic insufficiency fracture after TKA shared any specific characteristics. Methods: In a retrospective study, the characteristic features of 17 patients with early periprosthetic insufficiency fracture were reviewed. The index TKA was performed using a medial parapatellar approach and a cemented posterior-stabilized prosthesis. The demographic characteristics of the patients, including body mass index (BMI), preoperative alignment deformity, and postfracture bone mineral density (BMD), were evaluated. Results: The study population included 14 women and three men with the mean age of 71.4±7.2 yr. All patients returned with sudden sharp knee pain and inability to walk after the surgery. The mean time from surgery to the diagnosis of fracture was 23±13.3 days. Preoperative varus and valgus deformities were detected in 16 (94.1%) and one (5.9%) patient, respectively. The fracture occurred in the lateral condyle in all patients with varus deformity and the medial condyle in the patient with valgus deformity. All patients were identified with osteoporosis based on the post-fracture BMD evaluation. Thirteen (76.4%) patients were categorized as obese, and four patients as overweight. The size of the femoral condyle was small in the majority of patients. Conclusions: Severe knee deformity, osteoporosis, high BMI, and small size of the femoral condyle were the main risk factors of early periprosthetic insufficiency fracture. Level of Evidence: Level IV.

Minimum Five Years Follow-Up of Total Knee Arthroplasty Using Morphometric Implants in Patients With Osteoarthritis

BackgroundThe use of morphometric implants in total knee arthroplasty (TKA) has shown better early clinical outcomes compared to conventional implants. The primary objective of this study is to evaluate the functional outcome and the implant survivorship of a morphometric TKA at a minimum of 5 years of follow-up. MethodsFrom May 2012 to June 2015, all patients undergoing primary TKA with a single design of morphometric posterior-stabilized prosthesis (Persona; Zimmer) in a prospective observational single-center study were evaluated. The Knee Society Scoring System (KSS) and the Knee Injury and Osteoarthritis Outcome Score (KOOS) were completed preoperatively, 1, 3, and 5 years postoperatively. Kaplan-Meier was used to calculate survivorship of the implants. The average follow-up was 75 months. ResultsIn total, 237 TKAs were performed in 235 patients with a mean age of 73 years (49-90). The KSS Knee Score increased from 44.7 (13-64) preoperatively to 93.6 (71-100), the KSS Function Score from 45.8 (17-69) to 92.2 (51-98), and the KSS Satisfaction Score from 26.6 (16-51) to 41 (35-55) at 5 years of follow-up. Similarly, for the KOOS score, a significant improvement of all the subscales was observed at 5 years of follow-up. Implant survival without reoperation at 5 years of follow up was 98.72% (95% confidence interval 0.95-1.00). ConclusionThis is the first study demonstrating that significant improvements of the functional scores with good survivorship can be achieved at a minimum of 5 years of follow-up with TKA using morphometric implants.

Range of Motion Outcomes Post Cruciate-Retaining vs Posterior Stabilized Total Knee Arthroplasty: A Retrospective Multi-Centre Cohort Study

Background: The outcome for TKA (total knee arthroplasty) upon whether the posterior cruciate ligament is preserved with cruciate retaining (CR) prostheses or sacrificed with posterior stabilized (PS) prostheses are still debated between studies. Materials and Methods: We included a total of 144 knees operated with cemented fixed bearing primary CR or PS TKAs. Independent t-tests were conducted for the outcomes and possible confounding variables between groups where relevant, with analyses using Chi-squared tests for nominal data. Results: Operation on patients with age of lower than 65 years predicts increased intraoperative bleeding volume (p = 0.037), pre-operative range of motion (ROM) of less than 90 degrees was a predictor for better improved post-operative ROM (p 0.001) and PS prostheses is superior to CR in terms of ROM improvement (p = 0.04), however with both groups achieving similar maximum ROM (p = 0.308). Conclusion: Improvement of ROM is increased by the use of PS prostheses compared to CS prostheses, with pre-operative ROM as a possible confounding factor and the maximum ROM achieved for both prostheses being similar. Lower age of the operation is also related to increased intraoperative bleeding