Purpose
Accurate implant position in total knee arthroplasty (TKA) can potentially lead to better long-term functional outcomes and implant survival. Recent studies on whether better clinical results ...could be obtained from computer-navigated or conventional TKA were inconclusive. In addition, recent reviews only included short-term follow-up studies without performing quantitative mid- to long-term follow-up analysis. Thus, the purpose of the present study was to perform a meta-analysis comparing mid- to long-term clinical outcomes (such as knee scoring and functional results) and radiological outcomes (such as normal alignment of the limb axis or component) between computer-navigated TKA and conventional TKA to determine which method of TKA could obtain better clinical and radiological results.
Methods
MEDLINE, EMBASE, the Cochrane Central Register of Controlled Trials (CENTRAL), Web of Science, and SCOPUS electronic databases were searched for relevant articles published through August 2018 that compared outcomes of computer-navigated TKA and conventional TKA. Data search, extraction, analysis, and quality assessment were performed according to the Cochrane Collaboration guidelines. Clinical and radiological outcomes of both techniques were evaluated using various outcome measures.
Results
Seven randomized controlled trials were included. Based on Knee Society Scores, the Western Ontario and McMaster Universities Osteoarthritis Index, pain, and range of motion, there were no significant differences in clinical outcomes between the two techniques. Based on outliers from the normal axis, outliers of femoral components in the coronal plane, and outliers of tibial components in the coronal plane, radiologic outcomes showed no significant differences between the two techniques either.
Conclusions
The present study revealed that there were no significant differences in clinical or radiological outcomes between computer-navigated TKA and conventional TKA. It remains unclear which TKA technique yields better results in terms of mid- to long-term clinical and radiological outcomes.
Level of evidence
I.
Purpose
Kinematically aligned total knee arthroplasty (KA TKA) strives to restore the native distal and posterior joint lines of the femur. Because the joint lines of a virtually planned femoral ...component on the native femur can serve as surrogates of those of the native femur, the present study determined position and orientation deviations of the femoral joint lines following calipered KA TKA from virtually planned joint lines and whether these alignment deviations affect clinical outcomes. Our hypotheses were that the alignment deviations for most knees would be less than 2 mm and/or 2° and that larger alignment deviations would not be associated with lower clinical outcome scores.
Methods
A review of lower extremity CT scanograms and CT scans of the knee identified 36 patients treated with calipered KA TKA in one limb and no other skeletal deformities in either limb. 3D models of the operated femur with the implanted femoral component and the native femur were created. The articular surfaces of a 3D model of the implanted femoral component in the TKA knee were shape-matched to the condyles of the native femur to create a virtual plan. The shape-matched femoral component served as a reference from which to determine alignment deviations of the femoral component implanted in the ipsilateral femur. The Forgotten Joint Score (FJS) and Oxford Knee Score (OKS) were obtained at an average of 20 months.
Results
For proximal–distal and anterior–posterior positions and varus–valgus and internal–external orientations of the femoral component, the root mean square deviations from the planned joint lines ranged from 1.4 to 1.5 (mm or degrees). The mean differences ranged from − 0.1 to 0.2 (mm or degrees) indicating an absence of systematic alignment deviations. The proportion of knees with joint lines within ± 2 mm and ± 2° of the joint lines of virtually planned knees ranged from 83 to 92%. For the FJS and OKS, the median values were 79 (out of 100) and 45 (out of 48), respectively, and there were no significant correlations between deviations in the positions and orientations and either the FJS or the OKS.
Conclusion
Alignment deviations were bounded by 2 mm and 2° for most knees, which previous biomechanical studies have shown reduce the risks of stiffness, loss of extension, loss of flexion, and tibial compartment forces higher than those of the native knee. Moreover, because median FJS and OKS were relatively high, and because larger alignment deviations did not correlate with lower outcome scores, deviations did not affect clinical outcomes. These results validate calipered KA TKA as a surgical technique which closely restores the distal and posterior femoral joint lines to those planned and achieves concomitant high patient-reported outcome scores. Thus, surgeons can use the calipered KA TKA technique with confidence that the surgical alignment goal will be satisfied with sufficient accuracy that high patient-reported outcomes are achieved.
Level of evidence
III.
Purpose
Modern total knee arthroplasty (TKA) systems are designed to reproduce the normal knee kinematics and improve patient outcome. The authors compared two different third-generation medial pivot ...TKA implants, having a single-radius or a J-curve design in their sagittal plane, hypothesizing no clinical differences.
Methods
Two cohorts of 50 patients who underwent primary TKA were first preoperatively matched by sex, deformity, body mass index (BMI), Oxford Knee Score (OKS), Knee society score (KSS) and range of motion (ROM) and then statistically analyzed at a minimum follow-up (FU) of 2 years. An identical surgical technique, which aimed to reproduce a slightly tighter medial than lateral compartment, was used in all knees.
Results
At a minimum follow-up of 2 years (range 24–34 months) there were no statistically significant differences in OKS and KSS between the two implant groups. The final ROM differed statistically between the two groups: the average maximum active flexion was 123° in the J-curve femoral design group with an adapted “medially-congruent” polyethylene insert, and 116° in the single radius femoral design with a medial “ball-in-socket” articulation.
Conclusion
No clinical and radiological differences were found when the two cohorts of patients were compared. This study showed that the implant design played a minor role in the final outcome as opposed to a precise surgical technique.
Level of evidence
Retrospective case-control study, Level III.
Objectives:
To systematically review the incidence of postoperative complications and adverse events following primary ACLR with quadriceps tendon autograft, while secondarily comparing the reported ...rates in an all-soft tissue quadriceps tendon (QT) graft relative to quadriceps tendon grafts with a patellar bone plug (QTPB).
Methods:
Two independent authors conducted a literature search using PubMed, Embase, and Scopus databases using the Preferred Reporting Items for Systematic Meta-Analyses (PRISMA) guidelines. The search strategy included the following keywords combined with Boolean operators: ‘Anterior Cruciate Ligament’, ‘ACL’ ‘Reconstruction’, and ‘Quadriceps Tendon’. Inclusion criteria consisted of level I to IV human clinical studies in English or English-language translation reporting complications and adverse events after primary ACLR using quadriceps tendon autograft. The overall incidence of complications throughout the included studies, as well as the incidence of specific complications were extracted. A 2- proportion z-test was performed to evaluate for potential differences in the incidence of postoperative complications between ACLR with quadriceps tendon with and without a patellar bone plug.
Results:
A total of twenty studies, consisting of 2,381 patients (2,389 knees) with a mean age of 27 (mean range, 12 - 58) years, consisting of 68.3% males (n=1626/2381), were identified. The mean follow-up was 28.5 (mean range, 6 – 47) months. The total incidence of complications was 10.3% (n = 246/2389 patients), with persistent post-operative knee pain being the most common, as seen in 10.8% (n = 91/843) of knees. Patients who underwent ACL reconstruction with QT graft had increased incidence of persistent knee pain (23.3%) and reoperations (5.9%) when compared to QTPB grafts (8.6% and 3.2%, respectively) (p < .01). Nontraumatic graft ruptures were greater with the QTPB (2.1%) relative to QT (0.5%) (p = 0.01). There was no appreciable difference in total complications, total graft failures, traumatic rupture, ACLR revisions, cyclops lesions, or arthrofibrosis (all, p > 0.05). Patellar fractures occurred exclusively with the QTPB (2.2%).
Conclusions:
Complications following primary ACLR using quadriceps tendon autograft were recorded in 10.5% of knees, the most common of which is persistent knee pain. No difference was reported in the overall incidence of complications with the use of the QT versus QTPB grafts, however persistent knee pain was 2.7x greater with QT.
Objectives:
A tibial tubercle-trochlear groove (TT-TG) distance of 20 mm is typically used when determining whether tibial tubercle anteromedialization (AMZ) is needed for patellar instability. TT-TG ...distance, however, may depend on the internal/external (IE) rotation of the tibia in relation to the femur, which is typically not controlled for. Without knowledge of the variability in an individual’s TT-TG influenced by femorotibial rotation, the use of a specific TT-TG distance during pre-operative planning for patellar instability may lead to incorrect decisions on the use of tibial tubercle AMZ. We hypothesized that knee joint IE rotation is related to the TT-TG distance.
Methods:
A total of 8 independent human cadaveric knee specimens (age: 32±6; 4 males, 4 females) were utilized. A robotic manipulator (ZX165U, Kawasaki Robotics, Wixom, MI, USA) instrumented with a universal force/moment sensor was used to determine knee joint internal/external (IE) rotation under applied moments of ±5Nm at full extension. Two independent reviewers selected the trochlear groove and tibial tuberosity points on CT images of each specimen to define TT-TG (ICC=0.969). To determine the influence of knee joint IE rotation on TT-TG, 3D models generated from CT scans were registered to tibiofemoral kinematics. Subsequently, linear regression was performed to determine the relationship between knee joint IE rotation and TT-TG. Regression coefficient and standard error of measurement (α=0.05), and coefficient of determination (r2) were reported.
Results:
Knee joint IE rotation averaged 23.0 ± 4.2°. TT-TG changed by 12.1 ± 2.8 mm over this range. For every degree of knee joint IE rotation, TT-TG changed by 0.52 ± 0.07 mm (p<0.001 and r2>0.987). At neutral rotation, the TT-TG averaged 14.21 ± 5.0 mm.
Conclusions:
TT-TG was highly dependent on knee joint IE rotation changing by 0.52 mm for every degree of knee joint IE rotation. Thus, an offset in IE rotation of 10° would lead to a change in TT-TG of 5.2 mm, enough to alter surgical decision making for or against tibial tubercle AMZ. Physicians should pay close attention to knee joint IE rotation when measuring TT-TG in their patients, specifically in patients found to have a TT-TG near 20 mm, a key indication for surgical treatment of patellar instability.
Objectives:
Lateral patellar instability is a debilitating condition not only to athletes, but also a broad range of highly active individuals. Many of these patients experience instability symptoms ...bilaterally. Medial patellofemoral ligament reconstruction (MPFLR) is indicated to prevent future recurrence and ideally facilitate a complete return to sports (RTS). While RTS has been examined following MPFLR, the rate and timing of RTS in patients that undergo MPFLR bilaterally is unknown. The purpose of this study is to compare patients who have received bilateral MPFLR to a matched unilateral cohort, to elucidate potential differences and eventually allow better prognostication of this unique population’s ability to return to sports.
Methods:
Patients who underwent primary MPFL reconstructions with minimum 12-months clinical follow-up were identified from a single institution from the years 2011 to 2021. Those who underwent non-simultaneous primary MPFL reconstruction of bilateral knees were identified, as well as cohort of unilateral MPFLR. Surveys were then disseminated, including the Visual Analog Scale (VAS) for pain and satisfaction, the Kujala Anterior Knee Pain Scale, the Tegner Activity Scale, and the MPFL-RSI assessing psychological readiness to RTS. Detailed baseline sport activity and RTS information was collected, which was modified for bilateral patients to report on each procedure. For analysis, bilateral and unilateral MPFLRs were matched in a 1:2 ratio based on age, sex, BMI, and status of concomitant tibial tubercle osteotomy (TTO). A sub-analysis was performed comparing patients who underwent concomitant TTO compared to isolated MPFLR. Outcomes were compared between cohorts using T-tests and Chi-square analyses when required. Bivariate linear regression and logistic regression were performed to assess correlation between RTS and outcome scores, as well as psychological readiness.
Results:
Surveys were completed by 24 patients who underwent bilateral MPFL reconstruction and 105 unilateral patients with a total mean follow-up time of 4.2 ± 2.4 years. Among the bilateral patients, average time between MPFL procedures was 19.3 ± 16.9 months; notably, 71.4% of patients had symptoms in the contralateral knee at the time of index procedure. Three bilateral patients were unable to be matched, resulting in a 21:42 match with respective bilateral and unilateral cohorts having a mean age (22.5 ± 5.7 vs 23.3 ± 6.6 years; p = 0.65), sex (males 9/21 vs 18/42; p = 1.00), BMI (25.87 ± 6.39 vs 25.21 ± 4.78 kg/m2; p = 0.65), and concomitant TTO (9/18 vs 18/42; p = 1.00) that did not significantly differ, indicating successful matching. When comparing matched cohorts, bilateral MPFLR patients returned-to-sport at a similar rate to unilaterals following both their first (61.1% vs 63.2%; p = 0.98) and second MPFLR (72.7% vs 63.2%; p = 0.82). After undergoing both procedures, 33.3% of the bilateral cohort was able to return to their preinjury level of sport, compared to 26.3% of unilaterals (p = 0.82). The mean time for bilateral patient to RTS following their first procedure was 24.3 ± 7.5 weeks and 22.5 ± 12.9 weeks after their second, compared to the unilateral time-to-return taking 38.5 ± 23.0 weeks, though this difference at each time point (bilateral index vs unilateral; bilateral contralateral vs unilateral) did not reach significance (p = 0.06; p = 0.08). All patients scored highly with respect to VAS surgery satisfaction (85.4 vs 82.8; p = 0.44). There were no significant differences found between bilateral and unilateral cohorts for the Kulaja score (79.0 vs 86.1; p = 0.14) or in psychological readiness to RTS as indicated by the MPFL-RSI (49.7 ± 24.2 vs 58.8 ± 26.7; p = 0.24). Regression analysis found both the Kujala score (β = 0.06, p = 0.01) and MPFL-RSI (β = 0.06, p < 0.01) to be weakly, but significantly associated with rate of RTS. Sub-analysis of MPFLR with and without concomitant TTO did not demonstrate any significant differences with respect to RTS, psychological readiness, or any other outcome score (p > 0.05).
Conclusions:
The results of this study suggest that patients who undergo MPFLR bilaterally are able to return to sports at a similar rate and to a similar level compared to a matched unilateral comparison group with equivalent satisfaction and functional outcome scores. These findings are particularly important due to the high prevalence of simultaneous bilateral symptomatic patellar instability. With no demonstrable differences in rate and timing of return-to-sport, knee function, and psychological readiness between patients who have undergone unilateral versus bilateral MPFLR, surgeons can more confidently report equivalent outcomes to patients particularly with respect to RTS rates.
Objectives:
Meniscal injuries occur in as many as 1% of active people, and while outcomes for tears at the posterior medial meniscal root (PMMR) are well cited, the risk factors for injury have room ...for greater understanding. Incidence of disruption to the meniscotibial ligament (MTL) is correlated to occurrence of PMMR tears, suggesting that disruption to the MTL may increase forces at the PMMR and put the PMMR at greater risk of injury. The effect of an MTL disruption and repair on three-dimensional forces at the PMMR is unknown. The purpose of this study was to determine if MTL insufficiency alters forces at the PMMR., if a tenodesis procedure can restore PMMR forces to that of an MTL intact state, and to determine how knee flexion angle impacts PMMR root forces in the MTL intact and cut states.
We hypothesize that all shear forces will increase following MTL disruption.
Methods:
Ten fresh-frozen cadaveric knees (Average age: 53.2 years) were tested in three conditions (Intact, MTL Cut, MTL Tenodesis). Specimens were dissected down to the knee capsule with ligaments intact. A 3D load cell construct (Figure 1) was installed inside the tibia such that 3D forces of the PMMR could be measured when the joint was loaded. Each specimen was mounted to a materials testing machine (Instron) via a custom fixture that allowed the specimen flexion angle to be changed in 30 degree increments. The specimen was first loaded to 500 N of compression with 0 N-m of torque, then to 5 N-m of internal torque with 50 N of compression, and finally to 5 N-m of external torque with 50 N of compression. 3D forces at the PMMR were recorded for all loading sequences, and the process was repeated for each flexion angle (0°, 30°, 60°, and 90°). PMMR forces along each axis (compression- tension, anterior-posterior shear, and medial-lateral shear) were compared across MTL testing states across flexion angles using linear mixed modelling.
Results:
When the joint was loaded in compression, MTL Cut state significantly increased compression of the PMMR (p = 0.0368), and the Tenodesis state did not significantly restore tension-compression forces of the PMMR (Intact→Tenodesis: p = 0.008)(Figure 1). When the joint was loaded in external rotation, the MTL Cut State significantly increased compression (p < 0.0001), significantly decreased anterior shear (p = 0.0003), and, in high flexion angles, significantly decreased ML shear forces of the PMMR (Figure 1). The Tenodesis state did not significantly restore tension-compression (Intact→Tenodesis: p < 0.0001) or AP forces (Intact→Tenodesis: p = 0.0002) of the PMMR (Figure 1).
Conclusions:
The key finding of this study is that MTL disruption increases compression forces and decreases AP shear forces seen at the root when the joint is loaded in compression and external rotation. These findings indicate that the intact MTL protects the PMMR from compression and shear loads during movements where the joint is loaded in compression and external rotation, movements that are clinically reported to put the knee joint at risk of PMMR injury. The authors believe these relationships are observed because the MTL may play a role in maintaining meniscal hoop stresses, which converts joint compression loads into tension and shear forces along the meniscal attachment points. When the MTL is disrupted, the other meniscal attachment points, the PMMR included, see elevated compression loads as a result. This is the first study to measure 3D forces at the PMMR, a necessary capability to assess PMMR injury risk. It is notable that the tenodesis procedure performed in this study did not restore PMMR forces. Future studies should develop improved centralization or tenodesis procedures to better restore PMMR forces and decrease likelihood for PMMR injury after MTL disruption.
The posteromedial corner of the knee encompasses five medial structures posterior to the medial collateral ligament. With modern MRI systems, these structures are readily identified and can be ...appreciated in the context of multiligamentous knee injuries. It is recognized that anteromedial rotatory instability results from an injury that involves both the medial collateral ligament and the posterior oblique ligament. Like posterolateral corner injuries, untreated or concurrent posteromedial corner injuries resulting in rotatory instability place additional strain on anterior and posterior cruciate ligament reconstructions, which can ultimately contribute to graft failure and poor clinical outcomes. Various options exist for posteromedial corner reconstruction, with early results indicating that anatomic reconstruction can restore valgus stability and improve patient function. A thorough understanding of the anatomy, physical examination findings, and imaging characteristics will aid the physician in the management of these injuries.
Purpose
To determine whether knee stability, range of motion (ROM) and clinical scores differ between anterior-stabilized (AS) and posterior-stabilized (PS) total knee arthroplasty (TKA).
Methods
...This prospective randomized controlled trial included 34 patients with severe bilateral knee osteoarthritis who underwent bilateral TKA between June 2010 and July 2011 using AS and PS designs of a single-implant system. AS TKA with ultracongruent inserts was performed in one knee and PS TKA with a cam-post mechanism was performed in the other knee in each patient. Clinical and radiological data from a mean follow-up period of 5 years, including ROM, clinical scores, peak knee torque determined by isokinetic test, knee joint laxity determined by Telos stress views, tourniquet time and subjects’ preference were analyzed.
Results
The mean postoperative knee flexion angle did not differ between groups until 1 year. Beginning 2 years postoperatively, the knee flexion angle decreased slightly in the AS group and was smaller than that in the PS group (
p
= 0.004). The mean Knee Society knee score was higher in the PS group than in the AS group after 2 years. The quadriceps strength did not differ between groups. The mean posterior laxity after TKA was 6–8 mm greater in the AS group than in the PS group. No radiological loosening was observed in either group. More subjects preferred PS knees to AS knees. However, this difference was not significant.
Conclusion
AS primary TKA was inferior to PS TKA in terms of posterior knee stability, postoperative knee flexion and clinical scores after 2 years.
Level of evidence
Therapeutic study, Level 1.
