Anterior tibial displacement on preoperative stress radiography of ACL-injured knee depending on knee flexion angle

The optimal measurement method considering reliability and validity in the anterior knee laxity of anterior cruciate ligament tears

INTRODUCTION

To seek an optimal measurement method with high reliability and high validity for evaluation of the anterior knee laxity on stress radiographs and comparing the translation values to those of KT-2000 arthrometer.

METHODS

Anterior knee laxity in 77 patients was measured preoperatively using the TelosTM and the KT-2000 arthrometer. Side-to-side difference measurements were taken using three conventional measuring methods and one proposed method (Modified Lateral). The knee position on the stress radiograph was evaluated and scored based on the stress radiograph qualifying criteria depending on stress film correctiveness. Intraclass correlation coefficients were analyzed to evaluate the reliability of the measurement methods and were compared between high (Group H) and low (Group L) radiograph quality score groups for each method. Validity was assessed by comparing the KT-2000 and the TelosTM using Pearson correlation (r value).

RESULTS

The Modified Lateral method showed the best Intraclass Correlation Coefficients (ICCs), followed by Center to Center, and Medial to Medial and Lateral to Lateral methods without considering the quality of Telos. In the comparison between groups based on Telos quality for intra-rater reliability, the Medial to Medial (MM) method demonstrated the best reliability in both groups (MM: ICCs, Group H = 0.942, Group L = 0.917, P = 0.693). As for inter-rater reliability, the Modified Lateral (ML) method exhibited the best reliability in both groups (ML: ICCs, Group H = 0.923, Group L = 0.882, P = 0.547). The value measured using the ML method in Telos showed the highest correlation coefficient with the KT-2000 measured value in both groups H and L. There were no statistically significant differences among the correlation coefficient values.

CONCLUSION

The Modified Lateral method is recommended for its high reliability, taking into account the differences in bilateral knee positions and anatomical discriminability on stress radiographs when evaluating anterior knee translation with Telos. It also best reflected the KT-2000 arthrometer.

LEVEL OF EVIDENCE

Case Series, Level IV.

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.

Tibial internal rotation in combined anterior cruciate ligament and high-grade anterolateral ligament injury and its influence on ACL length

Background

Assessment of combined anterolateral ligament (ALL) and anterior cruciate ligament (ACL) injury remains challenging but of high importance as the ALL is a contributing stabilizer of tibial internal rotation. The effect of preoperative static tibial internal rotation on ACL -length remains unknown. The aim of the study was analyze the effect of tibial internal rotation on ACL length in single-bundle ACL reconstructions and to quantify tibial internal rotation in combined ACL and ALL injuries.

Methods

The effect of tibial internal rotation on ACL length was computed in a three-dimensional (3D) model of 10 healthy knees with 5° increments of tibial internal rotation from 0 to 30° resulting in 70 simulations. For each step ACL length was measured. ALL injury severity was graded by a blinded musculoskeletal radiologist in a retrospective analysis of 61 patients who underwent single-bundle ACL reconstruction. Preoperative tibial internal rotation was measured in magnetic resonance imaging (MRI) and its diagnostic performance was analyzed.

Results

ACL length linearly increased 0.7 ± 0.1 mm (2.1 ± 0.5% of initial length) per 5° of tibial internal rotation from 0 to 30° in each patient.

Seventeen patients (27.9%) had an intact ALL (grade 0), 10 (16.4%) a grade 1, 21 (34.4%) a grade 2 and 13 (21.3%) a grade 3 injury of the ALL. Patients with a combined ACL and ALL injury grade 3 had a median static tibial internal rotation of 8.8° (interquartile range (IQR): 8.3) compared to 5.6° (IQR: 6.6) in patients with an ALL injury (grade 0–2) (p = 0.03). A cut-off > 13.3° of tibial internal rotation predicted a high-grade ALL injury with a specificity of 92%, a sensitivity of 30%; area under the curve (AUC) 0.70 (95% CI: 0.54–0.85) (p = 0.03) and an accuracy of 79%.

Conclusion

ACL length linearly increases with tibial internal rotation from 0 to 30°. A combined ACL and high-grade ALL injury was associated with greater preoperative tibial internal rotation. This potentially contributes to unintentional graft laxity in ACL reconstructed patients, in particular with concomitant high-grade ALL tears.

Study design

Cohort study; Level of evidence, 3.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-022-05218-8.

Seeing Beyond Morphology-Standardized Stress MRI to Assess Human Knee Joint Instability

While providing the reference imaging modality for joint pathologies, MRI is focused on morphology and static configurations, thereby not fully exploiting the modality’s diagnostic capabilities. This study aimed to assess the diagnostic value of stress MRI combining imaging and loading in differentiating partial versus complete anterior cruciate ligament (ACL)-injury. Ten human cadaveric knee joint specimens were subjected to serial imaging using a 3.0T MRI scanner and a custom-made pressure-controlled loading device. Emulating the anterior-drawer test, joints were imaged before and after arthroscopic partial and complete ACL transection in the unloaded and loaded configurations using morphologic sequences. Following manual segmentations and registration of anatomic landmarks, two 3D vectors were computed between anatomic landmarks and registered coordinates. Loading-induced changes were quantified as vector lengths, angles, and projections on the x-, y-, and z-axis, related to the intact unloaded configuration, and referenced to manual measurements. Vector lengths and projections significantly increased with loading and increasing ACL injury and indicated multidimensional changes. Manual measurements confirmed gradually increasing anterior tibial translation. Beyond imaging of ligament structure and functionality, stress MRI techniques can quantify joint stability to differentiate partial and complete ACL injury and, possibly, compare surgical procedures and monitor treatment outcomes.

Clinical Outcomes of Arthroscopic Notchplasty and Partial Resection for Mucoid Degeneration of the Anterior Cruciate Ligament

Background: Mucoid degeneration of the anterior cruciate ligament (MD-ACL) is a chronic degenerative process involving a hypertrophied ACL, which may lead to notch impingement syndrome. As a treatment method, there is consensus regarding arthroscopic resection for MD-ACL resulting in good clinical outcomes; however, additional notchplasty remains controversial. The purpose of this study was to investigate clinical outcomes after arthroscopic partial resection of the ACL and additional notchplasty performed to minimize volume reduction of the ACL. Study Design: Level IIIb retrospective cohort study. Methods: Of 1810 individuals who underwent knee arthroscopic surgery performed by the same surgeon between July 2011 and October 2020, 52 were included, while 10 were excluded due to a follow-up period of <1 year. Clinical data including pain location, terminal flexion or extension pain, range of motion (ROM), Lysholm knee score, and Hospital for Special Surgery (HSS) knee score were assessed pre- and postoperatively. Additionally, according to the resected volume of the ACL, patients were classified into two groups: <25% (Group 1), and 25–50% (Group 2). Clinical outcomes were compared between the two groups. Results: There were 17 (40.5%) men and 25 (59.5%) women with a mean age of 53.9 years (range, 16–81 years) at the time of surgery. The mean duration of symptoms before surgery was 14.4 months (range, 3–66 months). Arthroscopic partial resection of the MD-ACL was performed in all patients, and concomitant notchplasty was performed in 36 (81.8%). All clinical scores improved postoperatively, and were statistically significant (p < 0.01). However, there was no significant difference in clinical outcomes between groups 1 and 2 classified according to the resected ACL volume. Recurrence of MD-ACL was recorded in only one patient, 11 months after arthroscopic treatment. No patients underwent ACL reconstruction because of symptoms of anterior instability. Conclusion: Arthroscopic partial resection of the ACL and concomitant notchplasty yielded satisfactory outcomes for the treatment of MD-ACL. Notchplasty may be an alternative procedure to avoid total ACL resection and postoperative instability.

Influence of Posterior Tibial Slope on Clinical Outcomes and Survivorship After Anterior Cruciate Ligament Reconstruction Using Hamstring Autografts: A Minimum of 10-Year Follow-Up

PURPOSE

To investigate the influence of medial and lateral posterior tibial slope (PTS) on long-term clinical outcomes and survivorship after anterior cruciate ligament (ACL) reconstruction using hamstring autografts.

METHODS

A total of 232 patients (mean age, 28.2 ± 8.9 years) who underwent primary ACL reconstruction from October 2002 to July 2007 were retrospectively reviewed. Patients with multiple ligament reconstruction, total meniscectomy, contralateral knee surgery before ACL reconstruction, open growth plate, and less than 10-year follow-up were excluded in the study. The medial and lateral PTS were measured from preoperative magnetic resonance imaging. Based on Li et al.'s previous study, the patients were divided into 2 groups according to their medial PTS (≤5.6° vs >5.6°) and lateral PTS (≤3.8° vs >3.8°), respectively. Clinical outcomes (clinical scores, stability tests and failure rate) were compared between the groups at the last follow-up. Furthermore, survival analysis was performed using the Kaplan-Meier method.

RESULTS

All clinical scores (International Knee Documentation Committee subjective, Lysholm, and Tegner activity scores) and stability tests (physical examinations and side-to-side difference in Telos stress radiographs) were insignificantly different between the 2 groups classified based on medial or lateral PTS. However, the failure rate was significantly higher in patients with medial PTS >5.6° (16.1% vs 5.1%, P = .01) or lateral PTS >3.8° (14.5% vs 4.7%; P = .01). The odds ratios of graft failure due to increased medial and lateral PTS were 3.18 (95% confidence interval, 1.22-8.28; P = .02) and 3.43 (95% confidence interval, 1.29-9.09; P = .01), respectively. In addition, the 10-year survivorship was significantly lower in patients with medial PTS >5.6° (83.9% vs 94.9%, P = .01) or lateral PTS >3.8° (85.5% vs 96.0%; P = .01).

CONCLUSIONS

Increased medial (>5.6°) and lateral (>3.8°) PTS were associated with higher failure rate and lower survivorship at a minimum of 10-year follow-up after primary ACL reconstruction using hamstring autografts.

LEVEL OF EVIDENCE

Level III, retrospective comparative trial.