Increased Accuracy of Varus Stress Radiographs Versus Magnetic Resonance Imaging in Diagnosing Fibular Collateral Ligament Grade III Tears

The Fibular Collateral Ligament Is a More Important Restraint to Varus Laxity Compared to the Anterolateral Complex in the Anterior Cruciate Ligament-Deficient Knee in a Cadaveric Biomechanical Study

PURPOSE

To compare the influence of the fibular collateral ligament (FCL) and the anterolateral complex (ALC) on varus knee laxity in paired anterior cruciate ligament (ACL)-deficient cadaveric knees using varus stress radiographs.

METHODS

Varus laxity in 9 paired (N = 18, mean age 73.8 years) human cadaveric knees was assessed using varus stress radiographs with a 12-Nm varus stress applied at 20° of knee flexion. All knees underwent testing in the intact state and following ACL sectioning. One knee of each pair was randomly assigned to undergo FCL sectioning, and the contralateral knee was assigned to undergo ALC sectioning (anterolateral ligament [ALL] followed by the Kaplan fibers).

RESULTS

Both FCL sectioning and ALC (ALL and the Kaplan fibers) sectioning resulted in increased lateral compartment gapping compared to the intact state, 2.44 mm and 1.13 mm, respectively. ALL sectioning with intact Kaplan fibers did not result in increased lateral compartment gapping. Paired knee comparison revealed a significantly greater influence of the FCL than the ALC in restraining lateral compartment gapping under an applied varus stress (P = .0003).

CONCLUSIONS

Sectioning the FCL resulted in significantly greater lateral compartment gapping under a varus stress than combined sectioning of the ALL and Kaplan fibers in an ACL-deficient knee, although both scenarios resulted in significantly increased gapping compared to the intact state. Sectioning of the ALL with intact Kaplan fibers did not result in increased lateral compartment gapping.

CLINICAL RELEVANCE

The FCL is the most important structure in restraining varus laxity in the ACL-deficient knee, and the ALC is of secondary importance in restraining varus laxity. In ACL-deficient patients with a high-grade pivot shift, mild varus laxity on clinical examination, and an intact FCL on magnetic resonance imaging, injury to the anterolateral complex should be considered and may be evaluated with varus stress radiographs. This study validates prior biomechanical studies of FCL deficiency and demonstrates that an approximately 1-mm increase in lateral compartment gapping on varus stress radiographs may occur secondary to ALC injury, and clinicians should be aware of this when considering treatment for ACL-deficient patients with high-grade anterolateral laxity.

Non-anatomical reconstruction of chronic posterolateral corner knee injuries show failure rates from 0% to 36% versus 4.3% to 24.2% for anatomic reconstruction techniques: An updated systematic review reflecting the 2019 expert consensus statement

OBJECTIVE

To review and update the literature regarding outcomes following surgical management of chronic, grade III posterolateral corner (PLC) injuries, with an emphasis on estimating failure rates based upon objective parameters in light of the 2019 expert consensus, while secondarily comparing the failure rates of anatomic versus non-anatomic reconstruction techniques.

METHODS

A literature search was performed using the PubMed, Embase, MEDLINE, and Cochrane Library databases. Inclusion criteria consisted of level I-IV human clinical studies reporting subjective and objective outcomes in patients following surgical management for chronic (>6 weeks from injury) grade III PLC injuries, with a minimum two-year follow-up. The criterion for objective surgical failure was based on post-operative varus stress radiographs and defined as a side-to-side difference of 3 ​mm or more of lateral gapping.

RESULTS

A total of six studies, consisting of 10 separate cohorts encompassing a total of 230 patients, were identified. PLC reconstruction was performed in all cohorts, with 80 ​% (n ​= ​8/10) of these cohorts utilising an anatomic reconstruction technique. A failure rate ranging from 4.3 ​% to 36 ​% was found. Subgroup analysis revealed a failure rate of 4.3 ​%-24.2 ​% for anatomic reconstruction techniques, whereas a 0 ​%-36 ​% failure rate was found for non-anatomic reconstruction. Arthrofibrosis was the most common complication (range, 0 ​%-12.1 ​%) following surgery. 0 ​%-8 ​% of patients required revision PLC surgery.

CONCLUSION

PLC reconstruction yields a wide variability in failure rates according to the side-to-side difference of 3 ​mm or more of lateral gapping on post-operative varus stress radiographs, with low revision rates following anatomic and non-anatomic reconstruction techniques.

LEVEL OF EVIDENCE

IV; Systematic Review of Level III and IV studies.

Reference standards for stress radiography measurements in knee ligament injury and instability: a systematic review

PURPOSE

Stress radiographs are an easily accessible, cost-effective tool in the evaluation of acute and chronic ligament knee injuries. Stress radiographs provide an objective, quantifiable, and functional assessment of the injured ligament and can be a useful adjunct when planning surgical management and to objectively assess postoperative outcomes. This study aimed to review the literature reporting on stress radiographic techniques in evaluating knee ligament injury and instability and propose thresholds for interpreting stress radiography techniques.

METHODS

The following three databases, OVID MEDLINE, the EMBASE library, and the Cochrane Controlled Trials Register, were systematically searched on January 23, 2023, for studies published from January 1970 to January 2023. The search extended to the reference lists of all relevant studies and orthopedic journals. Included studies were those that described a stress technique for the diagnosis of knee ligament injury; studies that reported a description or comparison of the accuracy and/or reliability of one or several stress radiography techniques, or studies that reported a comparison with alternative diagnostic modalities.

RESULTS

Sixteen stress radiography techniques were reported for assessing the ACL with stress applied in the anterior plane, 10 techniques for assessing the PCL with stress applied in the posterior plane, 3 techniques for valgus stress, and 4 techniques for varus stress. The Telos device was the most commonly used stress device in the ACL and PCL studies. There was no consensus on the accuracy and reliability of stress radiography techniques for the diagnosis of any knee ligament injury. Stress radiography techniques were compared with alternative diagnostic techniques including instrumented arthrometry, MRI, and physical examination in 18 studies, with variability in the advantages and disadvantages of stress radiography techniques and alternatives. Analysis of results pooled from different studies demonstrated average delta gapping in knees with a completely injured ligament compared to the normal contralateral knee as per the following: for the ACL 4.9 ± 1.4 mm; PCL 8.1 ± 2.5 mm; MCL 2.3 ± 0.05 mm; and the FCL 3.4 ± 0.2 mm.

CONCLUSION

Despite heterogeneity in the available literature with regard to stress examination techniques and device utilization, the data support that stress radiography techniques were accurate and reliable when compared to numerous alternatives in the diagnosis of acute and chronic knee ligament injuries. The present study also provides average increased ipsilateral compartment gapping/translation for specific knee ligament injuries based on the best available data. These values provide a reference standard for the interpretation of stress radiography techniques, help to guide surgical decision-making, and provide benchmark values for future investigations.

LEVEL OF EVIDENCE

III.

Accuracy of Magnetic Resonance Imaging in the Diagnosis of Multiple Ligament Knee Injuries: A Multicenter Study of 178 Patients

BACKGROUND

Magnetic resonance imaging (MRI) has shown limited diagnostic accuracy for multiple ligament knee injuries (MLKIs), especially posterolateral corner (PLC) injuries.

HYPOTHESIS

The diagnostic accuracy of MRI for MLKIs will only be moderate for some knee structures. Patient-related factors and injury patterns could modify the diagnostic accuracy of MRI.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

All patients with MLKIs surgically treated between January 2014 and December 2020 in the centers participating in the study were reviewed. We recorded sex, age, mechanism of injury, time from injury to MRI, and vascular and neurological associated lesions. Lesions to the anterior cruciate ligament (ACL), posterior cruciate ligament, medial collateral ligament, lateral collateral ligament (LCL), popliteus tendon, popliteofibular ligament, iliotibial band, biceps tendon, medial and lateral meniscus, and articular cartilage from MRI reports and surgical records were also collected. The sensitivity, specificity, positive predictive value, negative predictive value, diagnostic accuracy, diagnostic odds ratio, positive and negative likelihood ratio, and intraclass correlation coefficient of MRI were calculated for each knee structure. With logistic regression, associations between patient and injury characteristics and MRI accuracy were assessed.

RESULTS

A total of 178 patients (127 male; mean age, 33.1 years) were included. High-energy trauma was the most common mechanism of injury (50.6%), followed by sports trauma (38.8%) and low-energy trauma (8.4%). The ACL was the structure with the best diagnostic accuracy, diagnostic odds ratio, and positive predictive value (94.4%, 113.2, and 96.8%, respectively). PLC structures displayed the worst diagnostic accuracy among knee ligaments (popliteus tendon: 76.2%; LCL: 80.3%) and diagnostic odds ratio (popliteus tendon: 9.9; LCL: 17.0; popliteofibular ligament: 17.5). MRI was more reliable in detecting the absence of meniscal and chondral lesions than in identifying them. Logistic regression found that the diagnostic accuracy was affected by the Schenck classification, with higher Schenck grades having worse diagnostic accuracy for peripheral structures (iliotibial band, popliteus tendon, and biceps tendon) and improved diagnostic accuracy for the ACL and posterior cruciate ligament.

CONCLUSION

The diagnostic accuracy of MRI for MLKIs largely varied among knee structures, with many of them at risk of a misdiagnosis, especially PLC, meniscal, and chondral lesions. The severity of MLKIs lowered the diagnostic accuracy of MRI for peripheral structures.

Varus stress MRI in the refined assessment of the posterolateral corner of the knee joint

Magnetic resonance imaging (MRI) is commonly used to assess traumatic and non-traumatic conditions of the knee. Due to its complex and variable anatomy, the posterolateral corner (PLC)—often referred to as the joint’s dark side—remains diagnostically challenging. We aimed to render the diagnostic evaluation of the PLC more functional by combining MRI, varus loading, and image post-processing in a model of graded PLC injury that used sequential transections of the lateral collateral ligament, popliteus tendon, popliteofibular ligament, and anterior cruciate ligament. Ten human cadaveric knee joint specimens underwent imaging in each condition as above, and both unloaded and loaded using an MR-compatible device that standardized loading (of 147 N) and position (at 30° flexion). Following manual segmentation, 3D joint models were used to computationally measure lateral joint space opening for each specimen, configuration, and condition, while manual measurements provided the reference standard. With more extensive ligament deficiency and loading, lateral joint spaces increased significantly. In conclusion, varus stress MRI allows comprehensive PLC evaluation concerning structural integrity and associated functional capacity. Beyond providing normative values of lateral compartment opening, this study has potential implications for diagnostic and surgical decision-making and treatment monitoring in PLC injuries.

Effect of Sectioning of the Anterior Cruciate Ligament and Posterolateral Structures on Lateral Compartment Gapping: A Randomized Biomechanical Study

Background:

The contribution of anterior cruciate ligament (ACL) injury to lateral instability under varus stress, particularly compared with posterolateral structures, is not well known.

Purpose:

To investigate the effect of sectioning the ACL and posterolateral knee structures on lateral compartment gapping under varus stress.

Study Design:

Controlled laboratory study.

Methods:

Fourteen nonpaired cadaveric knees were randomized to 1 of 2 groups: sequential sectioning of the ACL, fibular collateral ligament (FCL), popliteus tendon (PLT), and popliteofibular ligament (PFL) (ACL-first group) or sequential sectioning of the FCL, PLT, PFL, and ACL (FCL-first group). Knees were loaded onto a custom jig at a 20° flexion angle. A standardized 12-N·m varus moment was applied to each specimen in the intact state and after each randomized sequential-sectioning state. Lateral compartment opening was measured on radiographs to assess the contribution to the increase in the lateral gap caused by resecting the respective structure. The distance was measured by 3 observers on 15 images (5 testing states each imaged 3 times) per specimen, for a total of 210 radiographs. The articular cartilage surfaces were not included in the measurements.

Results:

The mean increase in lateral opening after sectioning all structures (ACL and posterolateral corner) was 4.6 ± 1.8 mm (range, 1.9-7.7 mm). The ACL and FCL sectioning contributed the most to lateral knee opening (1.3 ± 0.6 and 2.2 ± 1.3 mm, respectively). In both groups, lateral gapping >3 mm was achieved only after both the ACL and FCL were sectioned. All comparisons of increased mean gapping distances demonstrated a significant difference with subsequent sequential sectioning of structures, except comparisons between the FCL and PLT and the PLT and PFL. When considering the effect of the ACL on lateral opening, no significant difference was found between sectioning the ACL first or FCL first (P = .387).

Conclusion:

ACL deficiency significantly increased lateral opening under varus stress, regardless of the sequence of injury. The effect of injury to the ACL in addition to the lateral structures should be considered when using varus stress radiographs to evaluate knee injuries.

Clinical Relevance:

With the current findings, understanding the effect of ACL and posterolateral corner injuries on lateral gapping under varus stress can aid in correctly diagnosing knee injuries and determining appropriate treatment plans.

Fibular Collateral Ligament Reconstruction Graft Options: Clinical and Radiographic Outcomes of Autograft Versus Allograft

PURPOSE

To compare varus knee stability and clinical outcomes between patients who underwent fibular collateral ligament reconstruction (FCLR) or lateral collateral ligament (LCL) reconstruction with autografts versus allografts when undergoing concomitant anterior cruciate ligament reconstruction (ACLR).

METHODS

All patients who underwent primary ACLR and concomitant FCLR from 2010 to 2017 performed by a single surgeon (R.F.L.) were retrospectively identified. Clinical characteristics and graft choices for FCLR were collected. Patients with a minimum 2-year follow-up for clinical outcome scores and 6-month stress radiographs were included. Patients with any other ligamentous procedure or revision ACLR were excluded.

RESULTS

We identified 69 primary ACLR with concomitant FCLR patients who met the inclusion criteria. Fifty patients underwent FCLR with semitendinosus autografts, and 19 with allografts. There were no significant side-to-side differences (SSDs) in lateral compartment gapping on varus stress x-rays between the 2 cohorts (allograft, 0.49 mm; autograft, 0.15 mm, P = .22), and no FCLR failures. There were no significant differences between autograft and allograft groups at minimum 2-year outcomes for 12-Item Short Form mental or physical composite score (SF12 MCS, P = .134; SF12 PCS, P = .642), WOMAC total (P = .158), pain (P = .116), stiffness (P = .061), or activity (P = .252); International Knee Documentation Committee (IKDC) (P = .337), Tegner (P = .601), Lysholm (P = .622), or patient satisfaction (P = .218). There were no significant differences in clinical knee stability between groups at an average follow-up of 3.6 years (P = 1.0).

CONCLUSION

There were no differences in varus stress laxity 6 months postoperatively or clinical outcome scores at ≥2 years postoperatively between patients having FCL reconstructions with either autograft or allograft. This study demonstrates that both hamstring autografts and allografts for FCL reconstructions offer reliable and similar radiographic and clinical results at short-term follow-up.

LEVEL OF EVIDENCE

III, retrospective comparative trial.

Stress Radiographs for Ligamentous Knee Injuries

Stress radiographs can provide an objective, quantifiable assessment of ligamentous knee injury. Commonly utilized techniques include varus, valgus, and posterior stress radiographs and can be used to augment findings on physical examination and magnetic resonance imaging. Both in vitro and in vivo studies have demonstrated reliability and validity of stress radiographs for diagnosing isolated and multiple ligament knee injuries. Varus stress radiographs are clinician applied at 20° flexion to detect injuries to the fibular collateral ligament and posterolateral corner. Valgus stress radiographs are clinician applied at 20° flexion to detect injuries to the medial collateral ligament or posteromedial corner. To evaluate the posterior cruciate ligament, posterior kneeling stress radiographs are obtained with the patient kneeling at 90° flexion on a firm platform. Bilateral radiographs are obtained and the side-to-side difference is compared to established criteria for injury severity. Stress radiographs support accurate diagnosis of complex knee injuries and also provide an objective measure of knee stability following ligament reconstruction. These imaging techniques can be performed in an ambulatory clinic setting with minimal additional equipment, and are thereby cost-effective, efficient, and support clinical decision-making in the treatment of complex knee injuries.

High-Grade Posterolateral Tibial Plateau Impaction Fractures in the Setting of a Primary Anterior Cruciate Ligament Tear Are Correlated With an Increased Preoperative Pivot Shift and Inferior Postoperative Outcomes After Anterior Cruciate Ligament Reconstruction

BACKGROUND

Impaction fractures of the posterolateral tibial plateau have been previously described to occur in association with anterior cruciate ligament (ACL) tears; however, the effect of these injuries on patient-reported outcomes (PROs) after ACL reconstruction (ACLR) is not well known.

PURPOSE

(1) To assess the effect of posterolateral tibial plateau impaction fractures on preoperative clinical knee stability assessed by the Lachman and pivot-shift examinations and (2) to assess the effect of impaction fractures on PROs after ACLR.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Patients undergoing ACLR for primary ACL tears with available magnetic resonance imaging (MRI) scans were included in this study. MRI scans were reviewed for the presence of posterolateral tibial plateau impaction fractures, which were classified according to the morphological variant. Associations with clinical laxity determined by an examination under anesthesia were assessed using binary logistic regression. Also, 2-year postoperative PROs (12-Item Short Form Health Survey [SF-12] Mental Component Scale and Physical Component Scale [PCS], Lysholm, Western Ontario and McMaster Universities Osteoarthritis Index [WOMAC], and Tegner scores) were modeled using multiple ordinal logistic regression to assess the effect of posterolateral tibial plateau impaction fracture classification while adjusting for other covariates. Pearson correlation coefficients (PCCs) were used to assess for correlations between postoperative PROs and the amount of tibial plateau bone loss present.

RESULTS

Displaced posterolateral tibial plateau impaction fractures were present in 407 (49.3%) of 825 total knees included in this study. Knees with type IIIB impaction fractures had an increased likelihood of having a high-grade pivot shift (odds ratio, 2.3; P = .047), with no other impaction fracture types showing a significant association. There were no significant associations between posterolateral tibial plateau impaction fracture type and a higher Lachman grade. Of the 599 eligible knees with 2-year follow-up, postoperative information was obtained for 419 (70.0%). Patients improved in all PROs at a mean of 3.0 years after ACLR (P < .001). Multiple ordinal logistic regression demonstrated a posterolateral tibial plateau impaction fracture as an independent predictor of the postoperative Lysholm score, with higher grade impaction fractures showing decreased Lysholm scores. Pearson correlation testing demonstrated weak but statistically significant correlations between sagittal bone loss of posterolateral tibial plateau impaction fractures and SF-12 PCS (PCC = -0.156; P = .023), WOMAC total (PCC = 0.159; P = .02), Lysholm (PCC = -0.203; P = .003), and Tegner scores (PCC = -0.151; P = .032).

CONCLUSION

When classified into distinct morphological subtypes, high-grade posterolateral tibial plateau impaction fractures were independently associated with decreased postoperative outcomes after ACLR when controlling for other demographic or clinical variables. Patients with large depression-type posterolateral tibial plateau impaction fractures (type IIIB) had an increased likelihood of having high-grade pivot-shift laxity on clinical examination under anesthesia.

Fibular Collateral Ligament Reconstruction in Adolescent Patients

Fibular collateral ligament (FCL) injuries can present as lateral-sided knee pain with feelings of side-to-side instability during activity. Patients with FCL injuries can have accompanying symptoms related to irritation of the common peroneal nerve. Preoperative diagnosis is imperative and should include a thorough physical examination complemented with varus stress radiographs before surgical reconstruction is indicated. In the adolescent cohort, surgical planning can be complicated by the presence of open physes, and caution must be taken to avoid drilling through or placing screw fixation across the physes. Potential complications include growth arrest and limb length discrepancy. Therefore, the purpose of this Technical Note is to describe an anatomic FCL reconstruction technique in the skeletally immature adolescent patient.

Repair and Augmentation with Internal Brace in the Multiligament Injured Knee

The internal brace is a ligament repair bridging concept using braided ultra-high-molecular-weight polyethylene suture tape and knotless bone anchors to reinforce ligament strength to allow early mobilization during early-phase healing. This concept can be used in the management of anterior cruciate ligament, posterior cruciate ligament, anterolateral ligament, medial collateral ligament, posteromedial corner, and posterolateral corner injuries. Ligament reinforcement is a concept in which a graft is reinforced and can be used in all aspects of knee ligament reconstruction. There has been a recent resurgence in ligament repair and recent evidence suggests equivalent outcome results.

Partial Controlled Early Postoperative Weightbearing Versus Nonweightbearing After Reconstruction of the Fibular (Lateral) Collateral Ligament: A Randomized Controlled Trial and Equivalence Analysis

BACKGROUND

While early weightbearing protocols have been advocated after anterior cruciate ligament (ACL) reconstruction, early weightbearing after fibular (lateral) collateral ligament reconstruction has not been well defined.

PURPOSE

(1) To determine if early partial controlled weightbearing after fibular collateral ligament (FCL) reconstruction resulted in an objective difference in laxity on varus stress radiographs at postoperative 6 months as compared with nonweightbearing, and (2) to determine if there was a difference in pain, edema, range of motion, and subjective patient-reported outcomes between these groups at 3 time points.

STUDY DESIGN

Randomized controlled trial; Level of evidence, 1.

METHODS

Patients were prospectively enrolled from January 2014 to April 2017. Patients who underwent isolated FCL reconstruction or combined ACL and FCL reconstructions were included in this study. Patients were randomly assigned to either a control group (nonweightbearing for 6 weeks) or a treatment group (partial controlled weightbearing at 40% body weight with crutches for 6 weeks). Patient-related data, including knee pain, edema, and range of motion, were collected for all patients at postoperative day 1, 6 weeks, and 6 months. Subjective outcomes were collected preoperatively and at 6 months postoperatively. The primary objective endpoint was varus stability, evaluated by bilateral varus stress radiographs obtained preoperatively and at 6 months postoperatively.

RESULTS

Thirty-nine patients were enrolled in the study, with 6-month follow-up obtained for 36 (92%). There was a significant improvement between the preoperative side-to-side difference (SSD) (2.4 ± 1.0) and postoperative SSD (0.2 ± 1.0) for lateral compartment laxity on varus stress radiographs among all patients ( P < .001). Clinical and statistical equivalence was found between groups in terms of SSD on varus stress radiographs ( P < .001). The SSD in knee edema was significantly lower in the partial early weightbearing group (beta = -0.6 cm, P = .001), but there were no significant group differences in knee pain, flexion, or extension. All patients demonstrated significant improvements in subjective outcome scores between the preoperative and 6-month postoperative conditions ( P < .001 for every score measured).

CONCLUSION

Clinical and statistical equivalence was found at postoperative 6 months between the early partial weightbearing and nonweightbearing groups among patients undergoing either an isolated FCL reconstruction or a combined ACL and FCL reconstruction. There were no significant differences observed between the groups regarding knee stability, pain, swelling, range of motion, or subjective outcomes. Given these findings, the authors recommend early partial weightbearing after isolated FCL reconstruction or combined ACL and FCL reconstruction.