Major Shortening of the Patellar Tendon During Septic Two-Stage Knee Arthroplasty Revision Using Static Spacers

BackgroundTwo-stage septic revision knee arthroplasty (TKA) often results in inferior functional outcome after reimplantation, which might be due to impairments of the extensor mechanism. The aim of the current study was to elucidate possible alterations in extensor mechanisms during septic two-stage revision of TKA treated with a static spacer.MethodsThis retrospective study included 87 patients (42 women, 45 men, age 64.5 ± 10.5; range, 29-85 years) undergoing septic two-stage TKA revision using a static spacer. The modified Insall Salvati ratio (mISR) was calculated via calibrated true lateral radiographs by two independent orthopedic surgeons before TKA explantation (G0), 6-8 days after TKA removal (G1), one day before TKA reimplantation (G2) and 6-8 days after TKA reimplantation (G3). Age, sex, body mass index (BMI), index C-reactive protein level, and number of previous surgeries were evaluated to identify the possible correlations.ResultsOverall, mISR significantly decreased within the first 6 days after index surgery from 1.71 ± 0.41 to 1.63 ± 0.41 (G0 versus G1, P < .001) and showed a further decline within the next 6 weeks to 1.54 ± 0.39 (G1 versus G2, P = .002). Conversely, mISR increased after reimplantation of TKA to 1.6 ± 0.43 (G3 versus G2, P = .08), though it did not regain preoperative baseline levels (G0 versus G3, P < .001). The subgroup with mISR decrease ≥10% experienced patellar tendon shortening of 16% between G0 and G1, 19% between G0 and G2 and up to 20% between G0 and G3. There were weak correlations concerning age (r = ?0.240, P = .038), preoperative C-reactive protein level (r = 0.239, P = .04) and patellar tendon shortening. Intraclass correlation coefficient (ICC)was 0.88 concerning radiographic measurement.ConclusionSeptic two-stage TKA revision using static spacers leads to irreversible alterations of the extensor mechanism, specifically a major shortening of the patellar tendon, in one out of 3 patients.Level of evidenceII.     

Does Unicompartmental Knee Replacement Offer Improved Clinical Advantages Over Total Knee Replacement in the Treatment of Isolated Lateral Osteoarthritis? A Matched Cohort Analysis From an Independent Center

BackgroundThe purpose of this study is to compare the functional and radiographic results, perioperative complications, satisfaction rate, and mid-term survivorship after unicompartmental knee arthroplasty (UKA) and total knee arthroplasty (TKA) for the treatment of lateral compartmental knee osteoarthritis (LCKO).MethodsBetween March 2007 and September 2017, we identified 35 patients with primary TKAs and 121 patients with lateral UKAs (LUKAs) for LCKO with a minimum follow-up of 2 years (mean 5.3 years, range 2-12.4). The matched variables were age, gender, operation side, body mass index, American Society of Anesthesiologist grade, initial diagnosis, osteoarthritis grade in lateral compartment, and follow-up time. All patients were assessed using the Oxford Knee Score, Hospital for Special Surgery score, range of motion, length of hospital stay, satisfaction, and complications. Survivorship of UKA and TKA implants was also compared.ResultsAt last follow-up, LUKA had a significantly better postoperative Oxford Knee Score, Hospital for Special Surgery score, range of motion, shorter length of hospital time, and higher satisfaction rate than matched TKA group. There were significant differences regarding patellar tendon injury (P = .043), superficial wound infection (P = .028), patellar snapping or impingement (P = .047), and stiffness (P < .001). Five-year survivorships free from revision were similar in both groups (99.2% vs 97.1%, P = .347).ConclusionLUKA for LCKO demonstrated more favorable 5-year results in comparison with TKA. Furthermore, LUKA achieved comparable mid-term survivorship and was less likely to suffer from wound infection and knee stiffness, although not overall surgical complications.     

Influence of Patellar Morphology Classified by Wiberg Classification on Knee Joint Function and Patellofemoral Tracking After Total Knee Arthroplasty Without Patellar Resurfacing

BackgroundTo evaluate the influence of patellar morphology on knee joint function and patellofemoral tracking in patients with primary osteoarthritis after total knee arthroplasty (TKA) without patellar resurfacing.MethodsWe performed a retrospective study of 156 patients with primary osteoarthritis who underwent TKA without patellar resurfacing from April 2018 to July 2019. As per Wiberg classification, patients were divided into Wiberg type I (group A, n = 38), II (group B, n = 88), and III (group C, n = 30) groups. The clinical data, postoperative follow-up data, and radiological data between three groups were compared.ResultsThere was no statistically significant difference in the HSS score and Feller score between the three groups before surgery and at each follow-up point after surgery (P > .05). At the last follow-up, there were no significant differences in the height and relative thickness of the patella between the three groups (P > .05). However, the incidence of anterior knee pain was significantly higher in group C than in the group B (P < .05). The patellar tilt angle was significantly larger in group C than in the groups A and B (both P < .05). The patellar facet angle was significantly larger in group A than in group B and C, which was also significantly larger in group B than in group C (both P < .05).ConclusionPatients with three different morphologic types of the patella both exhibited improved knee joint function after TKA, however, patients with Wiberg type Ⅲ patella were more prone to have poor patellofemoral tracking and anterior knee pain after surgery.     

Tibial Tubercle-Trochlear Groove Distance Influences Patellar Tilt After Total Knee Arthroplasty

BackgroundTibial tubercle-trochlear groove (TT-TG) distance is associated with a greater risk of recurrent patellar dislocation in young, active patients. However, the effect of TT-TG distance after total knee arthroplasty (TKA) has not been investigated. The purpose is to analyze the effect of TT-TG distance and component rotation on patellar tilt and patellar shift after TKA.MethodsAfter TKA, axial computed tomography scans and axial radiograph were taken in 115 consecutive knees. TT-TG distance was measured between the most anterior point of the tibial tuberosity and the deepest point of the femoral component relative to a line connecting the anterior condyles. Femoral and tibial component rotation was measured relative to the femoral and tibial rotational axis, respectively. Pearson correlation coefficients were calculated.ResultsTT-TG distance had a significant correlation with patellar tilt in extension (R = 0.220, P = .018), patellar tilt in flexion (R = 0.438, P < .001), and patellar shift (R = 0.330, P < .001). Tibial component rotation had a significant correlation with patellar tilt in flexion (R = −0.251, P = .007) and patellar shift (R = −0.360, P < .001). Femoral component rotation had no significant correlations. Tibial component rotation had a significant correlation with TT-TG distance (R = −0.573, P < .001), whereas femoral component rotation had no correlation (P = .192).ConclusionTT-TG distance had a significant correlation with patellar tilt and patellar shift. Surgeons need to understand the factors affecting TT-TG distance and to pay attention to avoiding excessive TT-TG distance after TKA.     

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.     

The Effect of Medial Release of the Distal Patellar Tendon Insertion on Lateral Patella Translation and Residual Insertion Strength: A Cadaveric Study

Patellar tendon avulsion is a risk with difficult exposure in a stiff knee, patella baja or previous tibial osteotomy. We sought to define a safe amount of release of the patellar tendon insertion for such cases. Eleven pairs of fresh frozen cadaveric lower limb specimens were acquired and randomized to either intact or partial release of the distal tibial insertion. Partial release of the tibial insertion of the tendon increased lateral exposure a mean 29% ± 15% (P = 0.002) while reducing ultimate strength to a mean of 80% that of the intact contralateral tendon. Measured patella release increased lateral patella translation and can be performed without risk of catastrophic rupture with basic activities of daily living following TKA.     

Patellar tendon rupture and marked joint instability after total knee arthroplasty

Background Patellar tendon rupture is a rare complication of total knee arthroplasty (TKA). Multiple repair methods have been described in the literature. Methods A 66-year-old woman suffered a patellar tendon re-rupture and marked joint instability within 6 months after revision TKA. She underwent re-revision TKA and extensor mechanism reconstruction with femoral quadriceps tendon and augmentation by a Leeds-Keio ligament. Result It was fairly difficult to acquire a satisfactory range of motion as well as gain in knee extension capacity by eliminating the extension lag. Conclusion Patellar tendon ruptures after TKA should be repaired as soon as they are recognized.     

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.     

Do Patients With Diabetes Have Poorer Improvements in Patient-Reported Outcomes After Total Knee Arthroplasty?

BackgroundDiabetes is one of the most common comorbidities in patients undergoing total knee arthroplasty (TKA) for osteoarthritis. However, the evidence remains unclear on how it affects patient-reported outcome measures after TKA.MethodsWe reviewed prospectively collected data of 2840 patients who underwent primary unilateral TKA between 2008 and 2018, of which 716 (25.2%) had diabetes. All patients had their HbA1c measured within 1 month before surgery, and only well-controlled diabetics (HbA1c <8.0%) were allowed to proceed with surgery. Patient demographics and comorbidities were recorded, and multiple regression was performed to evaluate the impact of diabetes on improvements in patient-reported outcome measures (Short Form 36 (SF-36), Western Ontario and McMaster University Osteoarthritis Index (WOMAC), Knee Society Score (KSS)) and knee range of motion (ROM).ResultsCompared with nondiabetics, patients with diabetes were more likely to possess a higher body mass index (P-value <.001), more comorbidities (P-value <.001), and poorer preoperative SF-36 Physical Component Summary (PCS) (P-value <.001), WOMAC (P-value = .002), KSS-function (P-value <.001), and knee ROM (P-value <.001). Multiple regression showed that diabetic patients experienced marginally poorer improvements in KSS-knee (?1.22 points, P-value = .025) and knee ROM (?1.67°, P-value = .013) than nondiabetics. However, there were no significant differences in improvements for SF-36 PCS (P-value = .163), Mental Component Summary (P-value = .954), WOMAC (P-value = .815), and KSS-function (P-value = .866).ConclusionPatients with well-controlled diabetes (HbA1c <8.0%) can expect similar improvements in general health and osteoarthritis outcomes (SF-36 PCS and Mental Component Summary, WOMAC, and KSS-function) compared with nondiabetics after TKA. Despite having marginally poorer improvements in knee-specific outcomes (KSS-knee and knee ROM), these differences are unlikely to be clinically significant.     

Patellar Tracking in Revision Total Knee Arthroplasty: Does Retaining a Patella From a Different Implant System Matter?

BackgroundPatellar maltracking is a potential surgical complication following total knee arthroplasty (TKA) and can result in anterior knee pain, recurrent patellar dislocation, and damage to the medial patellar soft tissue stabilizers. Data remain unclear as to whether the patellar button should be revised during a revision TKA (rTKA) if changing the component implant system. Our study examines whether retaining the original patellar button during an rTKA using a different implant system affects patellar tracking.MethodsA retrospective cohort study of rTKA patients between August 2011 and June 2019 was performed at an urban, tertiary referral center. Patients were divided into 2 cohorts depending on whether their retained patella from their primary TKA was of the same (SIM) or different implant manufacturer (DIM) as the revision system used. Radiographic measurements were performed on preoperative and postoperative knee radiographs and differences were compared between the 2 groups. Baseline demographic data were also collected.ResultsOf the 293 consecutive, aseptic rTKA cases identified, 122 underwent revision in the SIM cohort and 171 in the DIM cohort. There were no demographic differences between the groups. No statistical significance was calculated for differences in preoperative and postoperative patellar tilt or Insall-Salvati ratio between the groups. The DIM group was found to have more lateral patellar translation (?0.01 ± 6.09 vs 2.68 ± 7.61 mm, P = .001). However, when calculating differences in the magnitude of the translation (thereby removing differences due to laterality), no difference was observed (0.06 ± 3.69 vs 0.52 ± 4.95 mm, P = .394).ConclusionNo clinically significant differences in patellar tracking were observed when the original patellar component was retained and a different revision implant system was used. Given the inherent risks of bone loss and fracture with patellar component revision, surgeons performing rTKA may retain the primary patella if it is well fixed and can still expect appropriate patellar tracking regardless of the revision implant system used.Level of EvidenceIII, Retrospective cohort study.     

Changes in patellar height after anatomical ACL reconstruction with BTB autograft with a focus on patellar tendon removal volume

BackgroundAlthough anatomical anterior cruciate ligament reconstruction (ACLR) can provide satisfactory outcomes, little is known about how this procedure impacts patellar height. Since harvesting bone-patellar tendon-bone (BTB) autografts is a potential risk factor for decreased patellar height, we examined changes in patellar height after anatomical ACLR with BTB autograft with a focus on the size of the harvested graft.MethodsSubjects were 84 patients (49 males, 35 females; mean age, 23 years) who underwent primary anatomical ACLR with central third BTB autograft. Preoperative to postoperative Caton-Deschamps index (CDI) ratio was calculated using lateral knee radiographs before and 6 months after surgery. The length and cross-sectional area (CSA) of the graft were measured intraoperatively, and the CSA of the contralateral patellar tendon was measured by ultrasound 6 months postoperatively. The difference in graft CSA relative to the contralateral tendon CSA, expressed as a percentage (gCSA:ctCSA percentage), was also calculated.ResultsPatellar height decreased slightly after surgery (preoperative CDI: 0.856 ± 0.113; postoperative CDI: 0.841 ± 0.113), with a mean difference between preoperative and postoperative CDIs of −0.015 (range: −0.293 to 0.101). Although the CDI of male subjects significantly decreased after surgery (preoperative: 0.852 ± 0.117; postoperative: 0.827 ± 0.115), no significant changes were noted in female subjects (preoperative: 0.862 ± 0.108; postoperative: 0.861 ± 0.108). Graft length and CSA did not significantly impact the CDI ratio (r = −0.138 and r = −0.038, respectively). Moreover, no significant relationship was observed between the gCSA:ctCSA percentage and CDI ratio (r = 0.118).ConclusionsAlthough patellar height slightly, but significantly, decreased at 6 months after anatomical ACLR with BTB autograft, it was not affected by the length and CSA of harvested grafts. The decrease in postoperative patellar height was observed only in male subjects, suggesting the potential importance of sex differences in soft tissue healing during the postoperative period.     

Patellar Cut and Composite Thickness: The Influence on Postoperative Motion and Complications in Total Knee Arthroplasty

Background

Little data exist on the influence of patellar thickness on postoperative motion or complications after total knee arthroplasty (TKA). This study addresses the following questions: Is postoperative motion influenced by change in composite patellar thickness? Is change in patellar thickness associated with more complications? And do more complications occur in the knees with a patellar bone remnant (<12 mm) and a native patellar thickness <18 mm?

Total Knee Arthroplasty for Valgus Deformity via a Lateral Approach: Clinical Results,Comparison to Medial Approach,and Review of Recent Literature

BackgroundTotal knee arthroplasty (TKA) for valgus deformity is a challenge. The standard medial parapatellar approach may not be universally useful for this. We have adopted the lateral approach to valgus knees. Here we describe our experience with this approach, present early results, and compare them to the medial approach.MethodsOur institutional registry was queried for all patients with valgus deformity who underwent a TKA via a lateral approach between 2013 and 2016. The registry was also queried for patients with valgus deformity who underwent a TKA through a medial approach in previous years and this data was compared to the study group.ResultsSeventy-nine valgus knees in 72 patients were operated through a lateral approach. Deformity was corrected by 10.8°, from 16.2° to 5.4° (P < .001). Patellar tilt improved from −2.3° to 0.3° (P = .037). Seven implants (9%) were constrained. Mean operating time was 87 minutes (range 53-137). Twenty-five knees in 23 patients were operated via the medial approach. Deformity was corrected by 7.3°, from 13.2° to 5.9° (P < .001). Mean operating time was 137 minutes (range 90-230). Constrained implants were used in 16% of cases. The lateral approach allowed better correction of valgus deformity (10.8 vs 7.3, P = .03) and shorter operative times (87 vs 137 minutes, P < .001).ConclusionA lateral approach TKA for valgus deformity improves knee alignment and patellar tilt. Compared to the medial approach, it allows better correction of the deformity, shorter operating times, and perhaps less use of constrained implants.     

Prior Nonarthroplasty Surgery Increases Risk of Complication in Primary Total Knee Arthroplasty

BackgroundPrior ipsilateral knee surgery may increase the risk for complications after total knee arthroplasty (TKA). It remains unclear if the extent of previous surgery affects those risks disparately. The purpose of this study is to evaluate prior nonarthroplasty bony procedure (BP) and soft tissue only procedure (STP) as a potential risk factor for complications after TKA and determine the association with charges or reimbursement of the primary TKA.MethodsPatients who underwent primary TKA with previous knee surgery were identified using a national Medicare database and matched 1:5 to controls without prior knee surgery. Rates of postoperative medical and surgical complications were calculated in addition to hospital-associated charges and reimbursements. Logistic regression analysis was used to control for confounding factors.ResultsPatients who underwent BP (n = 835) had increased risk of readmission (58.6% vs 45.3%, odds ratio (OR) 1.72, 95% confidence interval (CI) 1.59-1.85, P < .001) and emergency room visits (14.5% vs 10.4%, OR 1.44, 95% CI 1.29-1.61, P = .001). Patients who underwent STP (n = 6766) had increased risk of readmission (58.1% vs 45.2%, OR 1.69, 95% CI 1.64-1.73, P < .001), emergency room visits (12.6% vs 0.7%, OR 1.33, 1.28-1.39, P < .001), revision (1.8% vs 1.4%, OR 1.33, 95% CI 1.21-1.47, P = .006), cerebrovascular accident (2.3% vs 1.7%, OR 1.33, 95% CI 1.22-1.46, P = .002), and venous thromboembolism (3.8% vs 3.2%, OR 1.21, 95% CI 1.13-1.29, P = .009). Prior surgery was associated with increased charges and reimbursements.ConclusionPrior ipsilateral knee surgery is associated with significantly increased risks of postoperative complications after primary TKA. Interestingly, previous STP but not BP increased the risk of short-term revision and venous thromboembolism.     

The Outcome of Total Knee Arthroplasty With and Without Patellar Resurfacing up to 17 Years: A Report From the Australian Orthopaedic Association National Joint Replacement Registry

BackgroundPatellar resurfacing in total knee arthroplasty (TKA) remains a controversial issue after more than 4 decades of TKA. Despite a growing body of evidence from registry data, resurfacing is still based largely on a surgeon’s preference and training. The purpose of this study is to provide long-term outcomes for patellar resurfaced compared to when the patella is not resurfaced.MethodsData from the Australian Orthopaedic Association National Joint Replacement Registry (1999-2017) were used for this study. The analysis included 570,735 primary TKAs undertaken for osteoarthritis. Hazard ratios (HRs) and 17-year cumulative percent revision rates were used to compare revision rates between 4 subgroups: minimally stabilized (MS) patellar resurfacing, posterior stabilized (PS) patellar resurfacing, MS unresurfaced, and PS unresurfaced patella. Additional analyses of the patellar implant type and a comparison of inlay and onlay patellar resurfacing were also performed.ResultsFor all primary TKA, procedures where the patella was not resurfaced have a higher rate of revision compared to procedures where the patella was resurfaced (HR, 1.31; confidence interval, 1.28-1.35; P < .001). Unresurfaced PS knees have the highest cumulative percent revision at 17 years (11.1%), followed by MS unresurfaced (8.8%), PS resurfaced (7.9%), and MS resurfaced (7.1%). Inlay patellar resurfacing has a higher rate of revision compared to onlay patellar resurfacing (HR, 1.27; confidence interval, 1.17-1.37; P < .001).ConclusionResurfacing the patella reduces the rate of revision for both MS and PS knees. MS knees with patellar resurfacing have the lowest rate of revision. Onlay patella designs are associated with a lower revision rate compared to inlay patella designs.     

Transosseous tunnels versus suture anchors for the repair of acute quadriceps and patellar tendon ruptures: A systematic review and meta-analysis of biomechanical studies

BackgroundMultiple techniques have been developed for the repair of acute quadriceps and patellar tendon ruptures with the goal of optimizing clinical outcomes while minimizing complications and costs. The purpose of this study was to evaluate the biomechanical properties of transosseous tunnels and suture anchors for the repair of quadriceps and patellar tendon ruptures.MethodsA systematic review of the PubMed and Embase databases was performed based on the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines using specific search terms and eligibility criteria. Meta-analysis was performed by fixed-effects models for studies of low heterogeneity (I² <25%) and random-effects models for studies of moderate to high heterogeneity (I² ≥25%).ResultsA total of 392 studies were identified from the initial literature search with 7 studies meeting the eligibility criteria for quadriceps tendon repair and 8 studies meeting the eligibility criteria for patellar tendon repair. Based on the random-effects model for total gap formation and load to failure for quadriceps tendon repair, the mean difference was 8.88 mm (95% CI, −8.31 mm to 26.06 mm; p = 0.31) in favor of a larger gap with transosseous tunnels and −117.25N (95%CI, −242.73N to 8.23N; p = 0.07) in favor of a larger load to failure with suture anchors. A similar analysis for patellar tendon repair demonstrated a mean difference of 2.86 mm (95% CI, 1.08 mm to 4.64 mm; p = 0.002) in favor of a larger gap with transosseous tunnels and −56.34N (95% CI, −226.75 to 114.07N; p = 0.52) in favor of a larger load to failure with suture anchor repair.ConclusionsTransosseous tunnels are biomechanically similar to suture anchors for quadriceps tendon repair. Patellar tendon repair may benefit from reduced gap formation after cycling with suture anchor repair, but the load to failure for both techniques is biomechanically similar. Additional studies are necessary to evaluate these and alternative repair techniques.Level of evidenceSystematic review and meta-analysis of biomechanical studies, Level V.     

Alteration of patellar tendon morphology in patellofemoral instability (trochlear dysplasia)

IntroductionTrochlear Dysplasia (TD) is a condition that is characterized by the presence of an abnormally shaped trochlear groove, which hinders the patellofemoral joint (PFJ) stability. PFJ stability is determined by static and dynamic structures around the knee joint. We analysed whether the patellar tendon morphology is altered in patients with patellofemoral instability in Trochlear Dysplasia (TD).Material and methodsMagnetic Resonance Imaging (MRI) studies for 50 consecutive knees with TD and 50 consecutive knees with normal PFJ morphology were obtained for evaluation. For each MRI study, the cross-sectional area (CSA) of the medial and lateral components of the patellar tendon was measured and used to calculate the cross-sectional area ratio (CSAR) by two readers.ResultsThere was a statistically significant difference in the CSAR of the lateral-to-medial components of the patellar tendon between knees with normal PFJ morphology and knees with TD (one way ANOVA, F (4,95) = 7.743, p < 0.001). Pairwise comparisons amongst the Dejour subtypes of TD, revealed a statistically significance difference (p < 0.05) in the CSAR ratio between patients with normal PFJ morphology, and patients with type A (p = 0.007) and type C, TD. There was moderate correlation between the readers on Intraclass Correlation Coefficient (ICC) analysis (ICC- 0.7).ConclusionOur findings reveals hypertrophy of the medial part of the patellar tendon in patients with PFJ instability and TD. These differences could reflect the dynamic compensatory changes occurring at the PFJ to counteract the laterally directed instability vectors found in this condition.     

Preoperative Radiological Parameters Predicting the Need for Lateral Retinacular Release in Total Knee Arthroplasty

BackgroundProper patellar tracking is essential for well-functioning total knee arthroplasty (TKA). Besides implanting components in the correct position and rotation, balancing parapatellar soft tissues is also important in aiding normal patellar tracking. Patellar maltracking during TKA can be improved by lateral retinacular release (LRR).MethodsWe studied the incidence of LRR in consecutive primary TKA with nonresurfaced patella and posterior-stabilized implant design. We analyzed data from 250 consecutive primary TKAs (212 patients) from January 2016 to May 2016. We evaluated the preoperative radiological parameters like patellar tilt, patellar shift, patellar morphology, Insall-Salvati ratio, femoro-tibial angle, distal femoral valgus angle, and proximal tibia varus angle which predict the need for LRR during TKA. We used multivariate regression analysis to find the association of individual radiological parameters and the LRR.ResultsThe need for LRR is significantly associated with preoperative radiological parameters like patellar shift and patellar tilt (P < .001). Compared to the nonreleased group, the adjusted odds of LRR were greater for morphological parameters like Wiberg type 3 patella (odds ratio [OR] 17.45, 95% confidence interval [CI] 7.21-42.20), lateral facet thinning (OR 4.38, 95% CI 2.37-8.07), lateral patellofemoral arthritis (OR 14.36, 95% CI 6.82-30.23), and coronal valgus deformity (OR 4.95, 95% CI 1.60-10.68).ConclusionPreoperative assessment of these radiological parameters in the axial view implies a high chance of tight lateral retinacular structures. This helps in identifying patients who have a higher likelihood for patellar maltracking during TKA. Appropriate LRR helps to provide better patellar tracking post TKA.     

Comparison of Contact Kinematics in Posterior-Stabilized and Cruciate-Retaining Total Knee Arthroplasty at Long-Term Follow-Up

BackgroundThere is controversy regarding the superiority of posterior-stabilizing (PS) total knee arthroplasty (TKA) and cruciate-retaining (CR) TKA. Substantial work has made comparisons between PS and CR TKA at follow-ups of less than 5 years. It was the goal of the present study to compare the kinematics at greater than 5 years postoperatively between CR and PS TKA, with a secondary goal of comparing patient function.MethodsA total of 42 knees were investigated, with equal representation in the PS and CR TKA groups. Patients underwent radiostereometric analysis imaging at 0°, 20°, 40°, 60° 80°, and 100° of flexion. Contact position, magnitude of excursion, and condylar separation on each condyle were measured. A Timed-Up-and-Go functional test was also performed by patients, with the total test time being measured. Preoperative and postoperative clinical outcome scores were also collected.ResultsThere were differences in contact position on both the medial and lateral condyles at multiple angles of flexion (P < .05). There was no difference (P = .89) in medial excursion; however, PS TKA had greater lateral excursion than CR TKA (P < .01). No difference (P > .99) was found in frequency of condylar separation. PS TKA was associated with faster (P = .03) total Timed-Up-and-Go test times. There were no differences in clinical outcome scores between the groups preoperatively or postoperatively.ConclusionWe found kinematic and functional differences that favor PS TKA. Our results suggest posterior cruciate ligament insufficiency in CR TKA, indicating that perhaps the cam/post systems in PS TKA better maintain knee kinematics and function long term.     

Comparison of Intravenous and Topical Dexamethasone for Total Knee Arthroplasty: A Randomized Double-Blinded Controlled Study of Effects on Dexamethasone Administration Route and Enhanced Recovery

BackgroundThe optimal route for dexamethasone (DEX) administration regimen for patients undergoing primary TKA has not been investigated. This study aims to determine whether intravenous and topical DEX provide different clinical effects in patients with TKA.MethodsIn this double-blinded, placebo-controlled trial, 90 patients undergoing primary TKA were randomized to intravenous DEX group (n = 45) or topical DEX group (n = 45, DEX applied in anesthetic cocktail for periarticular injection). The primary outcome was postoperative VAS pain score and morphine consumption. Secondary outcomes were included knee swelling, knee flexion, and extension angle, Knee Society Score (KSS), and postoperative hospital stays. Tertiary outcomes assessed the blood-related metrics, including inflammatory biomarkers and fibrinolysis parameters. Finally, nausea and vomiting and other adverse events were compared.ResultsThe topical administration of DEX provide lower pain score at 2h, 8h, 12h at rest (P < .05) and 12h, 24h with activity (P < .05), and less knee swelling in the first postoperative day (P < .05), while intravenous DEX was more effective in decreasing blood inflammatory biomarkers, including C-reactive protein (CRP) at postoperative 24h (P < .05) and interleukin-6 (IL-6) at postoperative 24h, 48h (P < .05), and reducing postoperative nausea (P < .05) for patients receiving TKA. However, there was no significant difference in knee flexion and extension angle, KSS, postoperative hospital stays, and complications occurrence (P > .05) between intravenous and topical DEX after TKA.ConclusionTopical administration of DEX provided better clinical outcomes on postoperative pain management and knee swelling early after TKA, while intravenous DEX was more effective in decreasing blood inflammatory biomarkers and preventing postoperative nausea.