Sagittal Laxity Research Articles

Limited correlation between physical performance and patient-reported outcomes at 1-year follow-up after anterior cruciate ligament reconstruction.

The majority of anterior cruciate ligament reconstruction (ACLr) patients wish to return to sport. Clinical evaluations after ACLr often do not include physical testing, making it difficult to determine the patient's readiness to return to sport. Thus, it would be helpful to identify easily assessable factors associated with physical function in ACLr patients that could inform planning of patients' return to sport. This study sought to evaluate the associations between physical test performance in ACLr patients and known ACL injury risk factors, knee laxity and patient-reported outcomes at 1-year follow-up. The cohort included isolated primary ACLr patients operated between 2009 and 2014. Patients were invited to a 1-year visit to clarify their readiness to return to sport. A test battery was performed, including clinical evaluation, patient-reported outcomes and three physical tests, from which the Leg Symmetry Index (LSI) was calculated. Multivariate regression analyses were performed for each of the physical tests, including known risk factors, clinical outcomes and patient-reported outcomes. Laxity <3 mm, pivot shift = 0, Knee Injury and Osteoarthritis Outcome Score (KOOS) sport >75, International Knee Documentation Committee (IKDC) >75.9, and Single Assessment Numeric Evaluation (SANE) >92.7 were applied as cut-off values for good versus poor status. A total of 480 ACLr patients were included in the study. Laxity <3 mm had a negative impact on the single-hop LSI, whereas a pivot shift = 0 or IKDC >75.9 had a positive impact on the single-hop LSI. Age <20, a pivot shift grade of 0 and KOOSsport >75 were positively associated with the triple-hop LSI. Finally, age <20 and IKDC >75.9 were positively associated with the leg extension strength LSI. Age, sagittal laxity, pivot shift and patient-reported outcomes were associated with physical test performance 1 year after ACLr. However, the associations were not completely uniform and strong, so information on age, sagittal laxity, pivot shift and patient-reported outcomes cannot replace a return-to-sport functional test battery in determining when it is safe to return to sport after ACLr. Level III.

Preserved posterior cruciate ligament contributed to knee sagittal stability, but not to rollback and deep knee flexion in cruciate-retaining total knee arthroplasty with a cruciate-substituting insert

PurposeNo previous report has compared the differences in postoperative functional outcomes between posterior cruciate ligament (PCL)-retaining (CR-) and PCL-sacrificing (CS-) total knee arthroplasty (TKA) with detailed intraoperative consideration of joint gap and balance. The purpose of this study was to evaluate the in vivo function of preserved PCL in TKA by comparing postoperative functional outcomes between CR- and CS-TKA with a cruciate-substituting insert (CS-insert), considering intraoperative influence factors, such as the posterior tibial slope, posterior condylar offset, joint gap, joint balance, and joint laxity. MethodsA total of 55 knees in 38 patients (27 knees from 18 patients in the CR group, and 28 knees from 20 patients in the CS group) were analyzed. Fluoroscopic evaluation under anesthesia in sagittal laxity, rollback amount, and the maximum flexion angles were compared between the groups. ResultsThere were no significant differences in intraoperative or postoperative all measurement values between the two groups, but the sagittal laxity was significantly smaller in the CR group [5.4% ± 4.5% (2.4 ± 2.1 mm)] than in the CS group [9.0 ± 3.8% (4.0 ± 1.7 mm)] (P ​< 0.01). There were no significant differences in the amount of rollback and postoperative maximum knee flexion angle between the groups. ConclusionsPreserved PCL in TKA with a CS-insert contributed to knee sagittal stability, but not to rollback and deep knee flexion.

Measurement of Tibial Orientation Helps Select the Optimal Insert Thickness to Personalize PCL Tension in a Medial Ball-in-Socket TKA.

As the conformity of a medial ball-in-socket total knee arthroplasty (TKA) provides intrinsic anterior-posterior (A-P) stability, surgeons cannot rely on the manual examination of sagittal laxity to identify the optimal insert thickness. Instead, the present study determined whether measuring tibial axial orientation in extension and 90° flexion with an insert goniometer could identify the optimal thickness that, when implanted, provides high postoperative function. In twenty-two patients that underwent unrestricted caliper-verified kinematic alignment (KA) with a PCL retaining implant, two surgeons measured tibial orientation in extension and 90° flexion with 10, 11, 12, and 13 mm thick insert goniometers. Each TKA had one insert thickness that restored either the maximum external tibial orientation in extension, the maximum internal tibial orientation at 90° flexion, or both relative to 1 mm thinner and thicker inserts. In addition, the 6-month median [interquartile range] Forgotten Joint Score of 73 (54–87) and Oxford Knee Score of 42 (38–45) indicated high satisfaction and function. In conclusion, surgeons using a medial ball-in-socket TKA design can measure external tibial orientation in extension and internal tibial orientation at 90° flexion with an insert goniometer. Furthermore, implanting an insert with the thickness that provided the maximum orientation values resulted in high postoperative function, thereby personalizing PCL tension.

Comparison of Rotatory and Sagittal Laxity After Single-Bundle Versus Double-Bundle ACL Reconstruction: Outcomes at 7-Year Follow-up.

Background:Biomechanical studies have shown excellent anteroposterior and rotatory laxity control after double-bundle (DB) anterior cruciate ligament (ACL) reconstruction, but no clinical studies have compared midterm (>5-year) residual laxity between the DB and single-bundle (SB) techniques.Purpose:To clinically compare sagittal and rotatory laxities and residual sagittal laxity on the KT-1000 arthrometer between patients treated with an SB ACL reconstruction and those treated with a DB ACL reconstruction at the 7-year follow-up.Study Design:Cohort study; Level of evidence, 3.Methods:A total of 110 patients were included between January 2006 and December 2007. The patients were randomly assigned into 2 groups: those treated with SB ACL reconstruction (n = 63) and those treated with the DB technique (n = 47). All patients were then reviewed at a minimum of 7 years of follow-up; patients with ACL rerupture (n = 3 in the SB group and n = 2 in the DB group) were excluded from the postoperative comparative analysis. Residual anterior laxity (Lachman test), rotatory laxity (pivot-shift test), and sagittal laxity (KT-1000 arthrometer side-to-side difference) were measured and compared between the 2 groups.Results:The mean age at surgery was 23.0 ± 5.1 years for the DB group and 28.1 ± 7.0 years for the SB group, and the mean follow-up was 7.4 ± 0.8 years. No statistically significant differences were found between the 2 groups in terms of age, sex, preoperative laxity on KT-1000, preoperative Tegner score, or concomitant meniscal lesions. Residual postoperative laxity via Lachman testing (P < .01), pivot-shift testing (P = .042), and the KT-1000 arthrometer (P < .01) was statistically significantly in favor of DB reconstruction.Conclusion:DB ACL reconstruction allowed better control of anterior stability during the evaluation via the Lachman test and via objective measurement on the KT-1000, as well as rotatory stability at a minimum of 7 years of follow-up.

A high level of knee laxity after anterior cruciate ligament reconstruction results in high revision rates.

The literature indicates a lack of consensus on the correlation between knee laxity after anterior cruciate ligament reconstruction (ACLR) and subjective clinical outcomes and the need for revision surgery. Therefore, using high-volume registry data, this study aimed to describe the relationship between objective knee laxity after ACLR and subjective symptom and functional assessments and the need for revision surgery. The hypothesis was that greater postoperative knee laxity would correlate with inferior patient-reported outcomes and a higher risk for revision surgery. In this study, 17,114 patients in the Danish knee ligament reconstruction registry were placed into three groups on the basis of objective side-to-side differences in sagittal laxity one year after surgery: group A (≤ 2mm), Group B (3-5mm) and Group C (> 5mm). The main outcome measure was revision rate within 2years of primary surgery, further outcome measures were the knee injury and osteoarthritis outcome score (KOOS) as well as Tegner activity score. The study found the risk for revision surgery was more than five times higher for Group C [hazard ratio (HR) = 5.51] than for Group A. The KOOS knee-related Quality of Life (QoL) sub-score exhibited lower values when comparing Groups B or C to Group A. In addition, the KOOS Function in Sportand Recreation (Sport/Rec) sub-score yielded lower values for groups B and C in comparison with Group A. These results indicate that increased post-operative sagittal laxity is correlated with an increased risk for revision surgery and might correlate with poorer knee-related QoL, as well as a decreased function in sports. The clinical relevance of the present study is that high knee laxity at 1-year follow-up is a predictor of the risk of revision surgery. III.

Not strong enough? Movements generated during clinical examination of sagittal and rotational laxity in a cadaver knee

ABSTRACT BACKGROUND: Injury to the anterior cruciate ligament (ACL) is associated with sagittal and rotational laxity, which is exacerbated by damage to the anterolateral capsuloligamentous structures, also known as the anterolateral ligament (ALL). The amount of laxity reported in biomechanical studies might be clinically insignificant during a surgeon's examination, possibly influencing clinical judgement. We aimed to measure whether the motion generated by clinicians in a cadaver model after the ACL and ALL were transected is clinically significant METHODS: A group of orthopaedic surgeons and trainees examined a cadaver knee for sagittal and rotational laxity at 30° and 90° with intact ligaments, after the ACL was transected, and after the ACL and ALL were transected. The examiners were blinded to the dissection process. Rotational and sagittal movements during these examinations were recorded by a computer-assisted surgery (CAS) system RESULTS: Twenty-four orthopaedic surgeons took part in the study. The median sagittal plane motion captured by CAS at 30° flexion was 7 mm (IQR 2 mm, p-value 0.32) in the intact knee, 9 mm (IQR 1 mm, p-value 0.34) after the ACL was cut and 9 mm (IQR 3 mm, p-value 0.63) after ACL and ALL were cut. The median arc of rotational motion at 30° was 19° (IQR 7°, p-value 0.12) in the intact knee, 24° (IQR 5°, p-value 0.56) after the ACL was cut, and 22° (IQR 6°, p-value 0.8) after the ACL and ALL were cut. None of the differences in these movements was significant CONCLUSION: The surgeons could not generate significant differences in sagittal or rotational motion in a cadaver model, which could be objectively detected by CAS, when examining the intact knee, ACL deficient (only), or combined ACL and ALL deficient knee. This challenges the utility of known clinical tests and calls for improved objective laxity assessment tools to provide input in clinical decision-making and measure outcomes of these injuries Level of evidence: Level 5 Keywords: knee, anterolateral ligament, anterior drawer's test, pivot shift, rotatory instability, anterior cruciate ligament, iliotibial band, Kaplan fibres

Comparison of Functional Outcomes, Femoral Rollback and Sagittal Stability of Anterior-Stabilized Versus Posterior-Stabilized Total Knee Arthroplasty: A Systematic Review and Meta-analysis of Randomized Controlled Trials.

Total knee arthroplasty (TKA) has improved leaps and bounds in terms of design to improve clinical outcomes and achieve better rehabilitation of the patients. Ultra-congruent inserts (UC) were designed to replace the need for posterior stabilized (PS) implants. The purpose of this review was to evaluate clinical outcomes, femoral rollback, functional scores, range of motion, sagittal laxity, complication rates, and isokinetic performance between UC and PS TKA among RCTs. Electronic databases such as PubMed, Scopus, opengrey, and Cochrane were searched from date of inception up to mid-April 2021, and meta-analysis was performed following PRISMA guidelines. This study analyzed outcomes, femoral rollback, tibial sagittal laxity and isokinetic performance. Ten RCTs identified 852 knees, of which 420 underwent UC TKAs and 432 underwent PS TKA. Compared to UC TKA, a significantly better sagittal stability (p = 0.17) and femoral rollback (p < 0.00001) in PS TKAs was noted, although no statistically significant difference was found in the assessment of the range of motion (p = 0.19) and functional scores. Both the groups had similar isokinetic performance with extensor torque (p = 0.97) and flexor torque (p = 0.37). We conclude with the current meta-analysis that there are no addedbenefits for UC over PS inserts and these insertshave a higher sagittal laxity and less femoral roll backin cruciate sacrificing UC knee. But since there are no long-term wear data, UC inserts with CS technique should be used cautiously and may be used only when the PCL cannot be balanced adequately. There is no evidence or only a few to support the superiority of the AS TKA in terms of clinical outcomes or isokinetic performance or femoral external rotation over PS TKA. Level I, Systematic review and meta-analysis of RCTs.

Combined Anterior and Anterolateral Stabilization of the Knee With the Hamstring Tendons

Anterior cruciate ligament reconstruction allows good control of sagittal laxity but insufficient rotary laxity control. Our objective is to describe an original lateral extra-articular tenodesis using gracilis in addition to an intra-articular reconstruction using the semitendinosus in a short 4-strand graft. The principles are as follows: The femoral tunnel for intra-articular and extra-articular reconstruction is unique, the femoral attachment is posterior and proximal to the lateral epicondyle, the graft is under the lateral collateral ligament, and the tibial insertion is isometric from 0° to 60° between the Gerdy tubercle and the fibular head.

Flexion gap stabilization by oversizing posterior condylar offset in deep-dished total knee replacement does not compromise flexion: A single-surgeon, retrospective, observational, mid-term series

IntroductionIn total knee replacement surgery, medio-lateral knee balancing is recognized as the key to achieving satisfactory functional results. But it may not be enough to stabilize the flexion gap using deep-dished implants. We achieved flexion gap balance by oversizing the femoral component, thus increasing the posterior condylar offset (PCO). The purpose of this study was to describe the applicability of this technique and to test whether it produced adverse effects on medium-term outcomes. We hypothesized that it would not compromise the results if used properly. We therefore asked: (1) at how many cases of flexion gap balance would require oversizing the femoral component; (2) if femoral components oversizing would modify the mid-term results as per forgotten joint score (FJS) scores and whether flexion gain would be comparable to patients in whom it was not increased. Materials and methodsNinety-four patients (120 knees) were operated between September 2009 and 2011 (age 68±9 years) using the cementless Hyperflex version of the Natural Knees (Zimmer, Warsaw, IN, USA). Postero stabilization was achieved using deep-dished inserts. The Gender configuration has provided narrow inserts to better adapt the female anatomy. A special navigation system measured the displacement of the lateral and medial femoro-tibial contact points with infra-millimetric precision. Adopting a tibial cut first, gap-balancing technique with anterior referencing, the decision to oversize the femoral component relied on the 90° flexion drawer test, which showed more than 6mm sagittal laxity before the femoral bone cuts. Eighty-one (105 knees) patients were reviewed with average 63±27-month follow-up. ResultsFemoral components were augmented by 1 size in 60 cases and by 2 sizes in 7 cases. At final review, knees with an oversized femoral component (60) achieved the same results as those implanted with a non-oversized femoral component (n=45) in terms of mean flexion gain (−5°±34 versus −4°±23, p=0.78), mean FJS (63±26 versus 61±23; p=0.56). ConclusionBalancing the Flexion gap by oversizing the femoral component did not compromise flexion range and functional results. Level of evidenceIV, Retrospective cohort study.

Correction to: Coronal and sagittal laxity affects clinical outcomes in posterior-stabilized total knee arthroplasty: assessment of well-functioning knees.

Unfortunately, the co-author "Hiroki Katagiri' was omitted in the original publication from the author group. The author name is added here. The original article has been corrected.

Coronal and sagittal laxity affects clinical outcomes in posterior-stabilized total knee arthroplasty: assessment of well-functioning knees.

Both coronal and sagittal laxity of well-functioning knees after total knee arthroplasty (TKA) was examined, and the correlations between the joint laxity and the clinical outcomes were analyzed to clarify the adequate joint laxity for the prosthesis, and the relationship between the laxity and the outcomes. Forty well-functioning TKA knees with a high-flexion posterior-stabilized (PS) prosthesis were studied. All patients were diagnosed as having osteoarthritis with varus deformity and were followed up for 2years or more. The coronal and sagittal laxity was assessed at extension and flexion, and the correlations between the joint laxity and the clinical outcomes were evaluated. The varus and valgus laxity averaged 5.6 ± 1.8° and 3.6 ± 1.2° at 10° knee flexion, and 7.4 ± 5.1° and 3.6 ± 2.7° at 80° knee flexion, respectively, and the AP laxity at 30° and 75° knee flexion averaged 8.7 ± 3.6mm and 6.6 ± 2.3mm, respectively. Knee flexion angle correlated with the joint laxity, while the other outcomes including patient-reported pain and instability were adversely affected by the greater laxity. This study exhibited the importance of consistent medial laxity both at extension and flexion, which averaged 3.6°. Care should be taken to maintain the medial stability and to obtain adequate laxity both at extension and flexion during surgery. A few degrees of medial tightness can be allowed to achieve excellent clinical results after TKA for preoperative varus knees. Therapeutic study, Level III.

Tibiofemoral bone bruise volume is not associated with meniscal injury and knee laxity in patients with anterior cruciate ligament rupture.

This study aimed at evaluating the association between the volume of the bone bruises and the magnitude of knee sagittal laxity and presence of meniscal injury in patients with anterior cruciate ligament (ACL) rupture. It was hypothesized that higher volumes of bone bruises will be associated with increased knee laxity and the presence of meniscal injury. Patients with clinical diagnosis of ACL injury were referred for magnetic resonance imaging (MRI) and knee sagittal laxity measurement with a mechanical instrumented device (Porto-Knee Testing Device). The femoral and tibial bone bruises were assessed by MRI and the volume measured by manually contouring the bone bruise using a computerized software and computed by a mathematical algorithm combining all measured areas. The ACL rupture type (partial or total), meniscal tear (medial or lateral), and the localization of bone bruise were also analyzed. Seventy-six ACL-ruptured participants were included and 34 patients displayed bone bruises. Tibiofemoral sagittal laxity was higher in participants with complete ACL rupture (p < 0.05), but not influenced by the volume of bone bruises and meniscal status (n.s.). The volume of bone bruises was not significantly associated with the meniscal lesion or with the tibiofemoral sagittal laxity, independently of the meniscal injury status (n.s.). The volume of femoral and/or tibial bone bruises was not associated with the type of ACL injury, tibiofemoral sagittal laxity or the status of meniscal injury. Bone bruises must be considered asa radiographic sign of injury and should not be suggestive of injury severity and not overvalued. Retrospective cohort study, Level III. 0011/0014.

Relationship between outcome scores and knee laxity following total knee arthroplasty: a systematic review

Background and purpose — Instability following primary total knee arthroplasty (TKA) is, according to all national registries, one of the major failure mechanisms leading to revision surgery. However, the range of soft-tissue laxity that favors both pain relief and optimal knee function following TKA remains unclear. We reviewed current evidence on the relationship between instrumented knee laxity measured postoperatively and outcome scores following primary TKA.Patients and methods — We conducted a systematic search of PubMed, Embase, and Cochrane databases to identify relevant studies, which were cross-referenced using Web of Science.Results — 14 eligible studies were identified; all were methodologically similar. Both sagittal and coronal laxity measurement were reported; 6 studies reported on measurement in both extension and flexion. In knee extension from 0° to 30° none of 11 studies could establish statistically significant association between laxity and outcome scores. In flexion from 60° to 90° 6 of 9 studies found statistically significant association. Favorable results were reported for posterior cruciate retaining (CR) knees with sagittal laxity between 5 and 10 mm at 75–80° and for knees with medial coronal laxity below 4° in 80–90° of flexion.Interpretation — In order to improve outcome following TKA careful measuring and adjusting of ligament laxity intraoperatively seems important. Future studies using newer outcome scores supplemented by performance-based scores may complement current evidence.

Posterior-stabilized inserts are preferable to cruciate-substituting ultracongruent inserts due to more favourable kinematics and stability.

It is unknown whether the conforming superiority of ultracongruent (UC) inserts over posterior stabilized (PS) inserts, due to an increased anterior lip for prevention of anterior displacement of the condyles during knee flexion, leads to better knee scores or greater knee stability in arthroplasty patients. This meta-analysis compared clinical outcomes, intraoperative kinematics, sagittal stability, and range of motion (ROM) between groups with either UC or PS inserts in primary total knee arthroplasty (TKA). Studies that recorded clinical outcomes, intraoperative kinematics, sagittal stability, and ROM in patients who underwent primary TKA with UC or PS inserts were included in the meta-analysis. Subgroup analyses based on differences in flexion angles were performed for intraoperative kinematics. Thirteen studies met the criteria for inclusion in the meta-analysis. The UC and PS insert groups reported similar pain scores (95% CI - 0.15 to 0.16; n.s.) and function scores (95% CI - 0.30 to 0.14; n.s.). In contrast, femoral rotation during flexion (95% CI - 0.06 to 6.35; p = 0.05), posterior femoral translation during flexion (95% CI - 2.74 to - 0.15; p = 0.03), tibial sagittal laxity at 90° (95% CI 2.91 to 7.72; p < 0.0001), and ROM (95% CI - 4.84 to - 1.53; p = 0.0002) differed significantly between the groups. Subgroup analyses revealed that the pooled data for femoral rotation were significantly different between groups: 60°, 4.09 (p < 0.00001); 90°, 7.94 (p < 0.00001); and 120°, 8.16 (p < 0.00001). Furthermore, pooled data for posterior femoral translation were significantly different between groups: 90°, - 3.70 (p < 0.00001); and 120°, - 3.96 (p < 0.00001). There were no significant differences in clinical outcomes between the groups with UC and PS inserts. However, the UC insert group showed significantly greater external femoral rotation, less posterior femoral translation, greater tibial laxity in the sagittal plane, and less ROM than the PS insert group. Based on the results of the current meta-analysis, in substituting the PCL, PS inserts are preferable to UC inserts due to more favourable kinematics and stability, even though both inserts have equivalent clinical outcomes. Therapeutic study, Level II.

Return to Sports after Acute Simultaneous Reconstruction of Anterior Cruciate Ligament Injury and Grade III Medial Collateral Ligament Injury

Objectives:Combined Anterior Cruciate Ligament (ACL) injury and Medial Collateral Ligament (MCL) injury account for 20% of knee ligament lesions. Conservative treatment of MCL and surgical ACL reconstruction are generally recommended. Significant medial instability after non-surgical management of MCL can lead to ACL reconstruction failure. The optimal management for athletes with combined ACL-MCL injuries remains controversial. The purpose of this study was to analyze the functional and clinical evolution of patients who underwent combined ACL-MCL surgery and their return-to-sport level with minimum 2-years follow-up.Methods:A total of 20 athletes with acute simultaneous ACL/Grade III MCL reconstructions were treated between March 2006 and January 2014. The minimum follow-up time was 24 months. Subjective functional results (IKDC, Lysholm), range of motion, anterior-medial and rotational stability (Lachmann, Pivot Shift, valgus stress) were evaluated. The ability to return to sport (Tegner) and the level achieved was recorded.Results:All patients significantly improved functional scores and stability tests. The mean subjective IKDC score improved from 37.7 ± 12.9 (range 21-69) preoperatively to 88.21 ± 4.47 (range 80-96) postoperatively (P <0.05). The average Lysholm score was 40.44 ± 10.58 (range 27-65) preoperatively and 90.83 ± 3.38 (range 84-95) postoperatively (P <0.05). Valgus and sagittal laxity was not observed (IKDC A 92% B 8%) at final follow-up. All patients had normal/nearly normal (IKDC A or B) mobility. All patients returned to sports; 90% reached the level they had prior to the ligamentous injury. Of all competitive athletes, 66% achieved the same level of sport.Conclusion:In athletes with acute ACL-Grade III MCL lesions, an early simultaneous reconstruction can significantly improve the medial and sagittal stability of the knee. This procedure resulted in excellent functional outcomes, with return to the same level of sports in the majority of patients at short-term follow-up.

Cruciate-sacrificing total knee arthroplasty and insert design: A radiologic study of sagittal laxity

IntroductionUltracongruent inserts avoid some of the drawbacks of central spine postero-stabilized inserts. However, early wear has been reported, and may be due to increased sagittal laxity. The principal objective of the present study was to compare sagittal laxity in rotating platform total knee replacements (TKR) according to insert design: ultracongruent versus central spine. The principal hypothesis was that insert design influences global sagittal laxity. Material and methodsA retrospective comparative study recruited 3 consecutive series of patients treated for primary osteoarthritis of the knee, with a minimum 1 year's follow-up. The UC series comprised 35 knees in 34 patients, receiving a Total Knee Triathlon™ (Stryker Orthopaedics, Mahwah, NJ) TKR with ultracongruent insert, at a mean 2.0 years’ follow-up. The UC+ series comprised 36 knees in 34 patients, receiving the BalanSys™ (Mathys Ltd, Bettlach, Switzerland) TKR with ultracongruent insert, at a mean 2.5 years’ follow-up; in this model, the anterior edge of the insert is higher than in the UC series (“deep-dish” design). The PS series comprised 43 knees in 40 patients, receiving a Total Knee Triathlon™ (Stryker Orthopaedics, Mahwah, NJ) TKR with central spine posterior stabilization, at a mean 1.5 years’ follow-up. The principal assessment criterion was sagittal laxity at 90° flexion as measured by the Telos Stress Device® (Metax GmbH, Hungen, Germany). ResultsSagittal laxity did not significantly differ between the UC and UC+ series: mean 8.2mm (range: 0–19.5mm) and 8.4mm (4.5–15.8mm), respectively. Sagittal laxity in the PS series was significantly less: 1.4mm (0.2–3.9) (P<0.0001). ConclusionSagittal laxity was greater in ultracongruent than central spine posterior stabilized TKR. This anteroposterior movement may induce polyethylene wear. The ideal degree of sagittal laxity for ultracongruent inserts remains to be determined. Level of evidenceIV – retrospective study.

Simultaneous Reconstruction of the Anterior Cruciate Ligament and Medial Collateral Ligament in Patients With Chronic ACL-MCL Lesions

Background: In cases of chronic anterior cruciate ligament (ACL)–medial collateral ligament (MCL) lesions, nonoperative treatment of the MCL lesion may lead to chronic valgus instability and rotatory instability. The optimal management for patients who have combined ACL-MCL injuries remains controversial. Purpose: To present a case series of 21 patients who underwent simultaneous ACL-MCL reconstruction with a 2- to 5-year follow-up. Study Design: Case series; Level of evidence, 4. Methods: From October 2007 to December 2010, a total of 21 patients with chronic ACL-MCL injuries, for which the 2 ligaments were reconstructed during the same surgical procedure, were studied. All patients were available for follow-up for at least 2 years. The International Knee Documentation Committee (IKDC) subjective knee scores, valgus and sagittal stability, anteromedial rotatory stability, range of motion, and complications were assessed both preoperatively and postoperatively. Results: At follow-up, valgus and sagittal laxity were not observed in any of the patients. The mean medial knee opening was significantly reduced to 0.80 ± 0.96 mm (range, –1.2 to 2.6 mm) postoperatively compared with 8.0 ± 1.3 mm (range, 6.1 to 10.7 mm) preoperatively (P < .01). The mean postoperative side-to-side difference measured with the KT-1000 arthrometer was reduced to 0.8 ± 0.9 mm (range, –1.2 to 2.3 mm) compared with 8.4 ± 1.6 mm (range, 6.2 to 13.2 mm) preoperatively (P < .01). Preoperative anteromedial instability was seen in 71% of patients (15/21), whereas none of the patients had anteromedial rotatory instability at the last follow-up. The mean IKDC subjective score improved overall from 45.3 ± 12.0 (range, 28.7-69.0) preoperatively to 87.7 ± 8.2 (range, 65.5-100.0) at the last follow-up (P < .01). Most patients (20/21) had normal or nearly normal range of motion of the knee joint; only 1 patient (5%) had a limitation of flexion of 15° compared with the contralateral knee at the last follow-up. Conclusion: In patients with chronic ACL-MCL lesions, simultaneous reconstruction of the ACL and MCL can significantly improve the medial, sagittal, and rotatory stability of the knee at short-term follow-up.

Bench Testing of a Knee Joint Arthrometer

The KT1000 and KT2000 knee joint arthrometers (MEDmetric Corp, San Diego, California) have been shown to overestimate the measurement of knee joint sagittal laxity. The purpose of this study was to investigate the accuracy of the KT arthrometers as measures of anterior and posterior linear displacement. The anterior and posterior linear displacements of 3 KT arthrometers (2 KT1000 arthrometers and 1 KT2000 arthrometer) were compared with the simultaneous displacement measured by a precision linear Vernier Dial Test Indicator (Davenport Ltd, London, United Kingdom). The displacement calculated using the analog output of the KT2000 was also compared with the values on the KT2000 displacement dial. Compared with the Vernier Dial Test Indicator, the KT arthrometers overestimated anterior linear displacement by between 22% and 24%. True anterior displacement for all 3 arthrometers, as recorded by the Vernier Dial Test Indicator, was found by multiplying the KT value by 0.79. When compared with the Vernier Dial Test Indicator, the KT arthrometers underestimated posterior linear displacement by between 18% and 19%. True posterior displacement, as recorded by the Vernier Dial Test Indicator, was found by multiplying the KT1000 value by 1.17 and the KT2000 value by 1.16. The internal apparatus of the KT2000 and KT1000 knee joint arthrometers overestimates anterior displacement and underestimates posterior displacement with a predictable relative systematic error. Future validation studies should use these correction equations to assess the accuracy of the KT arthrometers. Sagittal plane knee laxity measured with the KT devices requires systematic correction for optimal accuracy.

Long-term results after reconstruction of the ACL with hamstrings autograft and transtibial femoral drilling

To evaluate the long-term clinical, patient-reported and radiological outcome of patients reconstructed for anterior cruciate ligament (ACL) insufficiency. We wanted to examine the relationship between clinical findings and patient-reported scores. The 96 first successive patients that underwent ACL reconstruction using transtibial technique, hamstrings autograft and tunnel placement ad modum Howell were evaluated 10 years post-operatively. Subjective outcomes were Lysholm score, IKDC 2000 subjective score and Tegner activity scale. The clinical examination included evaluation of rotational and sagittal laxity. Evaluation of osteoarthritis was done radiologically. Eighty-three patients (86%) were available for follow-up at mean 10.2 years post-operatively. Three patients had revision ACL surgery prior to the 10-year evaluation. The mean Lysholm score, subjective IKDC 2000 score and Tegner activity scale were 89 (SD 13), 83 (SD 15) and 5 (range, 3-9), respectively. Six patients (8%) had moderate or severe osteoarthritis. Eighty-six per cent of patients had normal or near-normal anterior-posterior ACL laxity. Twenty per cent of patients had positive pivot shift and 42 % had a pivot glide. The former group had a significant lower Lysholm score compared to the rest of the patients. Although the mean Lysholm score was classified as good (89) at the 10-year follow-up, a positive pivot shift was found in 20% of these patients. Compared to patients with normal rotational laxity or pivot glide, this patient group reported significant lower subjective satisfaction at the long-term follow-up. Case series, level IV.

Associations Between Lower Extremity Muscle Mass and Multiplanar Knee Laxity and Stiffness

Background: Compared with men, women have disproportionally greater frontal (varus-valgus) and transverse (internal-external) plane laxity and lower stiffness, despite having similar sagittal (anterior-posterior) plane laxity and stiffness. While the underlying cause is unclear, the amount of lower extremity lean mass (LELM) may be a contributing factor. Hypothesis: Lower extremity lean mass would be a stronger predictor of frontal and transverse plane laxity and incremental stiffness than the sagittal plane. Associations between LELM and stiffness would be stronger at lower force increments. Study Design: Descriptive laboratory study. Methods: Sixty-three women and 30 men with no history of ligament injury were measured for knee laxity and incremental stiffness in the sagittal (−90- to 130-N posterior-to-anterior directed loads), frontal (±10-N·m varus-valgus torques), and transverse (±5-N·m internal-external rotation torques) planes and underwent dual-energy X-ray absorptiometry scans to measure LELM. Linear regressions examined the extent to which LELM predicted each laxity and stiffness value, while also accounting for a person’s sex. Results: Females (vs males) had greater laxity and less stiffness in the frontal and transverse planes but not the sagittal plane. Lower extremity lean mass was a poor predictor of sagittal laxity and stiffness (R2 range = .021-.081; P > .06) but was a stronger predictor of frontal (R2 range = .215-.567; P < .01) and transverse (R2 range = .224-.356; P < .01) plane laxity and stiffness. Associations were stronger for low (R2 = .495-.504) versus high (R2 = .215-.435) frontal plane stiffness but were similar for low (R2 = .233-.293) versus high (R2 = .224-.356) transverse plane stiffness. Once we accounted for a person’s LELM, sex had little effect on laxity and stiffness (change in R2 after removal = .01-.08; P = .027-.797). Conclusion: Less LELM was associated with greater laxity and less stiffness in frontal and transverse planes, which may contribute to the disproportionally higher laxities and reduced stiffnesses observed in females in these planes. Clinical Relevance: Frontal and transverse plane laxity and stiffness may be modifiable through strength training interventions that promote changes in muscle characteristics (eg, muscle cross-sectional area, stiffness) that may contribute to static knee joint stability, thus dynamic joint stability during sport activity.