Anterolateral ligament injuries in knees with an anterior cruciate ligament tear: Contribution of ultrasonography and MRI

Objectives

To describe the pathological appearance of the anterolateral ligament (ALL) on US and MRI in knees with an anterior cruciate ligament (ACL) tear.

Methods

This prospective study included 30 patients who had a suspected acute ACL tear. Their injured and contralateral knees were evaluated with radiography, US and MRI. Two radiologists evaluated the ALL on the MRI and US examinations. Agreement between these examiners’ findings was evaluated with Cohen’s kappa.

Results

On US examination, the ALL was found to be injured in 63% of cases (19/30; k = 0.93). The enthesis was found to be torn in 50% of cases (15/30; k = 1), with the tear located at the tibial attachment in all instances. On the MRI exam, the ALL was found to be injured in 53% of cases (16/30; k = 0.93). The enthesis was found to be torn in 13% of cases (4/30; k = 0.76), with the tear located at the tibial attachment in all instances (k = 0.93).

Conclusion

ALL injuries that occur with ACL tears are located at the tibial enthesis. They are often associated with bone avulsion at the enthesis and are better viewed on US.

Key Points

? ALL injuries often occur in combination with ACL tears. ? ALL injuries can be assessed with ultrasonography and MRI. ? ALL injuries associated with ACL tears are located at the tibial enthesis.

     

Patients with high-grade pivot-shift phenomenon are associated with higher prevalence of anterolateral ligament injury after acute anterior cruciate ligament injuries

Purpose

To compare the prevalence of concomitant anterolateral ligament (ALL) injury between patients with high-grade (grades II and III) pivot-shift and those with low-grade (grades 0 and I) pivot-shift phenomenon after acute anterior cruciate ligament (ACL) injuries.

Methods

Sixty-eight patients with an acute ACL injury who showed high-grade (grades II and III) pivot-shift phenomenon were enrolled as the study group. They were matched in a 1:1 fashion to another 68 ACL-injured control participants who showed low-grade (grades 0 and I) pivot-shift phenomenon during the same study period. Patients were matched by age, sex, and time from injury to surgery. A standardized pivot-shift test was performed under anesthesia for all the patients. Two blinded musculoskeletal radiologists reviewed the magnetic resonance imaging (MRI) scans for the presence of concomitant ALL injury. The grade of an ALL injury was divided into grade 0 (normal), grade I (sprain), grade II (partial tear), and grade III (complete tear). The prevalence and the grade of concomitant ALL injury were further compared between the study group and the control group.

Results

Overall, the prevalence of concomitant ALL injury in the study group (94.1%, 64/68) was significantly higher than that in the control group [60.3%, (41/68), P?<?0.05]. Specifically, there were 49 patients (49/64, 76.6%) who showed grade II/III (partial/complete tear) MRI evidence of concomitant ALL injury, which was also significantly higher than that in the control group (12/41, 29.3%).

Conclusions

Patients with high-grade pivot-shift phenomenon showed higher prevalence of concomitant ALL injury compared to those with low-grade pivot-shift phenomenon after acute ACL injuries. Careful assessment and proper treatment of this concomitant injury should be considered especially in knees with high-grade pivot-shift phenomenon.

Level of evidence

III.

     

Reconstructing the anterolateral ligament does not decrease rotational knee laxity in ACL-reconstructed knees

Purpose

Little is known about the anterolateral ligament’s (ALL) influence on knee laxity. The purpose of this study was to investigate rotational knee laxity against a pure axial rotational stress using radiostereometric analysis (RSA) after cutting and reconstructing both the anterior cruciate ligament (ACL) and the ALL.

Methods

Eight human donor legs were positioned and stereoradiographically recorded at 0°, 30° and 60° of knee flexion using a motorised fixture, while an internally rotating force of 4 Nm was applied to the foot. Anterior–posterior and rotational laxity were investigated for knees with intact ligaments and compared with those observed after successive ACL and ALL resection and reconstruction.

Results

After cutting the ALL in ACL-deficient knees, the internal rotation was increased in all three knee flexion angles, 0° (p?=?0.04), 30° (p?=?0.03) and 60° (p?<?0.01) by 1.0°, 1.6° and 2.5°, respectively. However, no decrease in laxity was found after reconstructing the ALL in ACL-reconstructed knees.

Conclusions

The ALL was confirmed as a stabiliser of internal rotation in ACL-deficient knees. However, reconstructing the ALL using a gracilis autograft tendon did not decrease the internal rotation laxity in the ACL-reconstructed knee. Based on the results of this study, we do not recommend reconstructing the ALL in ACL-reconstructed knees to decrease internal knee laxity.

     

Combined reconstruction of the anterolateral ligament in chronic ACL injuries leads to better clinical outcomes than isolated ACL reconstruction

Purpose

To evaluate the results of combined anterior cruciate ligament (ACL) and anterolateral ligament (ALL) reconstruction in patients with chronic ACL injury. It was hypothesized that patients who underwent combined ACL and ALL reconstruction would exhibit less residual laxity and better clinical outcomes.

Methods

Two groups of patients were evaluated and compared retrospectively. Both groups consisted only of patients with chronic (more than 12 months) ACL injuries. Patients in group 1 underwent anatomical intra-articular reconstruction of the ACL and patients in group 2 underwent anatomic intra-articular ACL reconstruction combined with ALL reconstruction. The presence of associated meniscal injury, the subjective International Knee Documentation Committee (IKDC) and Lysholm functional outcome scores in the postoperative period, KT-1000 evaluation, the presence of residual pivot shift and graft rupture rate were evaluated.

Results

One hundred and one patients who underwent reconstruction of chronic ACL injuries were evaluated. The median follow-up was 26 (24–29) months for group 1 and 25 (24–28) months for group 2. There were no significant differences between groups regarding gender, age, duration of injury until reconstruction, follow-up time or presence of associated meniscal injuries in the preoperative period. Regarding functional outcome scores, patients in group 2 presented better results on both the IKDC (p?=?0.0013) and the Lysholm (p?<?0.0001) evaluations. In addition, patients in group 2 had better KT-1000 evaluation (p?=?0.048) and a lower pivot shift rate at physical examination, presenting only 9.1% positivity versus 35.3% in the isolated ACL reconstruction (p?=?0.011). Regarding re-ruptures, group 1 presented 5 (7.3%) cases, and group 2 presented no cases.

Conclusion

The combined ACL and ALL reconstruction in patients with chronic ACL injury is an effective and safety solution and leads to good functional outcomes with no increase in complication rate. The clinical relevance of this finding is the possibility to indicate this type of procedure when patients present with more than 12 months after injury for surgery.

Level of evidence

Level III.

     

Sectioning the anterolateral ligament did not increase tibiofemoral translation or rotation in an ACL-deficient cadaveric model

Purpose

The anterolateral ligament (ALL) has been proposed as a possible extra-articular stabiliser of the knee. Injury to the ALL may result in residual instability following surgical reconstruction of a ruptured anterior cruciate ligament (ACL). Few studies have evaluated the biomechanical role of the ALL. The purpose of this study was to investigate whether sectioning the ALL would have an influence on tibiofemoral translation or rotation during the anterior drawer, Lachman, pivot shift, external rotation, and internal rotation tests in an ACL-deficient knee.

Methods

Only whole-body specimens having an ALL were included in this study. Lachman, anterior drawer, external rotation, and internal rotation tests were performed manually. Pivot shift test was done using a mechanised pivot shifter. The amount of tibiofemoral translation and rotation was recorded by a navigation system. Each specimen was tested in its native state, after sectioning the ACL, and after combined sectioning of the ACL and the ALL.

Results

In six out of 14 cadaveric knees, an ALL could be identified. The ACL-deficient knee had significantly more tibiofemoral translation and rotation compared to the native knee (P < 0.05). However, no changes in the magnitudes of translation or rotation were seen after subsequent sectioning of the ALL compared to the ACL-deficient knee (P > 0.05).

Conclusion

Adding an ALL lesion in an ACL-deficient knee did not increase tibiofemoral instability in this cadaveric model. It remains unclear whether injury to the ALL would result in substantial knee instability in the setting of ACL injury in vivo. Further research is warranted to fully elucidate the role of the ALL during knee kinematics and to determine in which scenarios ALL repair would be warranted. Understanding the function of the ALL may improve the current treatment strategies for ACL ruptures.

     

Quantitative magnetic resonance imaging (MRI) morphological analysis of knee cartilage in healthy and anterior cruciate ligament-injured knees

Purpose

To analyze the morphological change in the cartilage of the knee after anterior cruciate ligament (ACL) injury by comparing with that of the intact contralateral knee.

Methods

A total of 22 participants (12 male and 10 female patients) who had unilateral ACL injury underwent MRI scan of both the injured and intact contralateral knees. Sagittal plane images were segmented using a modeling software to determine cartilage volume and cartilage thickness in each part of the knee cartilage that were compared between the ACL-injured and the intact contralateral knees. Furthermore, the male and female patients’ data were analyzed in subgroups.

Results

The ACL-injured knees had statistically significant lower total knee cartilage volume than the intact contralateral knees (P = 0.0020), but had similar mean thickness of total knee cartilage (not significant: n.s.). In the male subgroup, there was no significant difference in cartilage volume and thickness between normal and ACL-injured knees. In the female subgroup, the ACL-injured knees demonstrated statistically significant difference in total knee cartilage volume (P = 0.0004) and thickness (P = 0.0024) compared with the normal knees. The percentage change in the cartilage thickness in women was significantly greater than that in men.

Conclusion

Cartilage volume was significantly smaller in the ACL-injured knees than in the contralateral intact knees in this cohort. Women tended to display greater cartilage volume and thickness change after ACL injury than men. These findings indicated that women might be more susceptible to cartilage alteration after ACL injuries.

Level of evidence

III.

     

Complete posterolateral meniscal root tear is associated with high-grade pivot-shift phenomenon in noncontact anterior cruciate ligament injuries

Purpose

The purpose of this study was to investigate whether the complete posterolateral meniscal root tear (PLMRT) would be associated with high-grade pivot-shift phenomenon in noncontact anterior cruciate ligament (ACL) injuries.

Methods

From 2013 to 2015, a total of 1095 consecutive patients were diagnosed as having noncontact ACL injuries and underwent primary ACL reconstructions. Among them, 140 patients were arthroscopically verified to have concomitant PLMRTs. Application of the exclusion criteria finally left 74 patients who were finally allocated into high-grade pivot-shift (grades II and III) group (n?=?51) and low-grade pivot-shift (grades 0 and I) group (n?=?23) according to the results of pre-operative pivot-shift tests performed under anesthesia. Predictors of high-grade pivot-shift phenomenon, including degree of PLMRTs, integrity of posterior MFLs, status of lateral meniscal extrusion, age, sex, body mass index (BMI), and KT-1000 arthrometer side-to-side difference (SSD), were assessed by multivariable logistic regression analysis.

Results

The proportion of patients with complete PLMRT in high-grade pivot-shift group was significantly larger than that in low-grade pivot-shift group. In addition, complete PLMRT was significantly [odds ratio (OR) 4.044; 95% CI 1.125–14.534; P?=?0.032] associated with high-grade pivot-shift phenomenon in noncontact ACL injury, especially for those with a time from injury to surgery of ≥12 weeks (OR 16.593; 95% CI 1.073–56.695; P?=?0.014). However, no significant association was identified between neither the integrity of posterior MFLs nor the status of lateral meniscal extrusion and the high-grade pivot-shift phenomenon.

Conclusion

Complete PLMRT is identified to be an independent risk factor of high-grade pivot-shift phenomenon in noncontact ACL injuries, particularly for those with a time from injury to surgery of ≥12 weeks.

Level of evidence

IV.

     

Kinematics of ACL and anterolateral ligament. Part I: Combined lesion

Purpose

To quantify the influence of ALL lesions on static and dynamic laxity in ACL-deficient knee.

Methods

The study was performed in 10 fresh-frozen knees. The joints were analysed in the following conditions: intact, ACL resection and ACL + ALL resection. Testing parameters were defined as: anterior displacement at 30° and 90° of flexion (AP30, AP90) applying a manual-maximum load; internal rotation at 30° and 90° of flexion (INT30, INT90) applying a 5 N m torque and internal rotation and acceleration during manual pivot-shift (PS) test. Kinematics was acquired by a navigation system; a testing rig and a torquemeter were used to control the limb position and the applied torque. Paired Student’s t test was conducted to assess statistical difference, and significance was set at P < 0.05.

Results

The ALL resection determined a significant increase in terms of internal rotation (INT30 P = 0.02, INT90 P = 0.03), while AP30 (P n.s) and AP90 (P n.s) were not affected. ALL resection produced a significant increase in terms of acceleration during PS test (P < 0.01), but no significant change in PS internal rotation was observed.

Conclusion

The ALL plays a significant role in controlling static internal rotation and acceleration during PS test. On the other hand, ALL resection did not produce any significant change in terms of anterior displacement. A trend was seen for the internal rotation during the pivot-shift test to increase after ALL resection was higher when compared to the intact and isolated ACL lesion states; however, the differences were not significant. The results highlight the clinical relevance of this structure that should be assessed before an ACL reconstruction in order to avoid residual laxity.

     

Anterior cruciate ligament tibial insertion site is elliptical or triangular shaped in healthy young adults: high-resolution 3-T MRI analysis

Purpose

To clarify the morphology of anterior cruciate ligament (ACL) tibial insertion site in healthy young knees using high-resolution 3-T MRI.

Methods

Subjects were 50 ACL-reconstructed patients with a mean age of 21.4 ± 6.8 years. The contralateral healthy knees were scanned using high-resolution 3-T MRI. The tibial insertion sites of the anteromedial (AM) and posterolateral (PL) bundle fibres, and the ACL attachment on the anterior horn of lateral meniscus (AHLM) were segmented from the MR images, and 3D models were reconstructed to evaluate the morphology. The shape of ACL footprint was qualitatively analysed, and the size of AM and PL attachments and AHLM overlapped area was measured digitally.

Results

Tibial AM and PL bundles were clearly identified in 42 of 50 knees (84.0%). Morphology of the whole ACL tibial insertion site was elliptical in 23 knees (54.8%) and triangular in 19 knees (45.2%), but not classified as C-shape in any knees. However, the AM bundle attachment was of C-shape in 29 knees (69.0%) and band-like in 13 knees (31.0%). Overlap of ACL on AHLM was found in 26 knees (61.9%), and the size of the overlapped area was 4.8 ± 4.7% of the whole ACL insertion site.

Conclusion

3D morphology of the intact ACL tibial insertion site analysed by high-resolution 3-T MRI was elliptical or triangular in healthy young knees. However, the AM bundle insertion site was of C-shape or band-like. A small lateral portion of the ACL was overlapped with the AHLM. As for clinical relevance, these findings should be considered in order to reproduce the native ACL insertion site sufficiently.

Level of evidence

III.

     

Histological analysis of the tibial anterior cruciate ligament insertion

Purpose

This study was performed to investigate the morphology of the tibial anterior cruciate ligament (ACL) by histological assessment.

Methods

The native (undissected) tibial ACL insertion of six fresh-frozen cadaveric knees was cut into four sagittal sections parallel to the long axis of the medial tibial spine. For histological evaluation, the slices were stained with haematoxylin and eosin, Safranin O and Russell–Movat pentachrome. All slices were digitalized and analysed at a magnification of 20×.

Results

The anterior tibial ACL insertion was bordered by a bony anterior ridge. The most medial ACL fibres inserted from the medial tibial spine and were adjacent to the articular cartilage of the medial tibial plateau. Parts of the bony insertions of the anterior and posterior horns of the lateral meniscus were in close contact with the lateral part of the tibial ACL insertion. A small fat pad was located just posterior to the functional ACL fibres. The anterior–posterior length of the medial ACL insertion was an average of 10.8 ± 1.1 mm compared with the lateral, which was only 6.2 ± 1.1 mm (p < 0.001). There were no central or posterolateral inserting ACL fibres.

Conclusions

The shape of the bony tibial ACL insertion was ‘duck-foot-like’. In contrast to previous findings, the functional mid-substance fibres arose from the most posterior part of the ‘duck-foot’ in a flat and ‘c-shaped’ way. The most anterior part of the tibial ACL insertion was bordered by a bony anterior ridge and the most medial by the medial tibial spine. No posterolateral fibres nor ACL bundles have been found histologically. This histological investigation may improve our understanding of the tibial ACL insertion and may provide important information for anatomical ACL reconstruction.

     

Radiographic femoral bicondylar width predicts anterior cruciate ligament insertion site sizes

Purpose

The purpose of this study was to determine whether radiographic femoral bicondylar width predicts intra-operative anterior cruciate ligament (ACL) insertion site sizes.

Methods

Seventy-three consecutive patients (39 males and 34 females; mean age 25.2 years ± 10.2) who underwent anatomic ACL reconstruction were retrospectively reviewed. Femoral condyle width was measured using a pre-operative anteroposterior (AP) radiograph of the operative knee. Lines were drawn through the anatomic axis of the femur, as well as perpendicularly through the condyles. Bicondylar width was measured as the maximum width across both the medial and lateral femoral condyles utilizing this perpendicular line. The ACL insertion site lengths (in the AP direction) of both the tibia and the femur were measured intra-operatively using a commercially available arthroscopic ruler.

Results

The average bicondylar width was significantly smaller for females compared to males (p < 0.05). The average tibial and femoral insertion site sizes were significantly smaller for females compared to males (p < 0.05). Regression analysis predicted tibial (r ² = 0.88) and femoral (r ² = 0.90) insertion site sizes based on femoral bicondylar width measurements.

Conclusion

A simple radiographic measurement of femoral bicondylar width can predict intra-operative tibial and femoral insertion site sizes, which has the potential to assist surgeons in performing individualized ACL reconstruction in cases where MRI scan is unavailable.

Level of evidence

IV.

     

The correlation between anterior cruciate ligament injury in elite alpine skiers and their parents

Purpose

The aim of this study was to investigate whether a familiar correlation with anterior cruciate ligament (ACL) injury exists between competitive alpine skiers and their parents.

Methods

All 593 (293 males, 300 females) elite alpine skiers who have studied at a Swedish alpine Ski High School during 2006 and 2012 answered a questionnaire whether they or their parents had suffered an ACL injury. A total of 418 skiers (70 %) answered the questionnaire.

Results

Twenty-nine per cent (n = 19) out of the 65 ACL-injured skiers reported that they had a parent (mother or father) who have had an ACL injury. In skiers without an ACL injury (n = 353), the result was 18 % (n = 64). An odds ratio of 1.95 (95 % confidence interval 1.04–3.65) was found to suffer an ACL injury if you have a parent who has had an ACL injury compared with if you have a parent without any ACL injury.

Conclusion

The findings of the current study demonstrated a family history to tear the ACL between alpine skiers who had studied at a Swedish Ski High School and ACL injuries of their parents.

Level of evidence

III.

     

Tibiofemoral joint congruence is lower in females with ACL injuries than males with ACL injuries

Purpose

Previous research has demonstrated that women have a higher risk of anterior cruciate ligament (ACL) injury than men. Tibiofemoral articular geometry may play a role in the occurrence of ACL tears. The purpose of this study was to analyze the gender-specific geometric characteristics differences in tibiofemoral morphology in ACL-deficient patients.

Methods

Medial tibial slope (MTS), lateral tibial slope (LTS), medial tibial plateau concavity, medial and lateral femoral condyle convexity, and lateral plateau convexity were analyzed in 276 patients with complete ACL injuries (138 females and 138 males). Two blinded observers measured the anatomical parameters of tibiofemoral geometry with use of multiplanar CT scans. Intra- and inter-rater reliabilities were assessed and comparisons between anatomic measures were made between male and female patients.

Results

The average ICC for all measurements was 0.90 (range 0.83–0.97) indicating good reliability. Male ACL injured patients demonstrated significantly greater LTS (10.5°?±?2.8) than female patients (9.6°?±?3.5°; p?<?0.05). No gender difference in MTS was found (n.s.). Medial and lateral femoral condyle convexity and medial tibial plateau concavity were greater in males than females (all p?<?0.05). Lateral tibial plateau convexity in females was higher than in males (p?<?0.001). The medial and lateral compartments were found to be more incongruent in females than males (p?<?0.01 and p?<?0.001, respectively).

Conclusions

Female patients were noted to have more incongruent medial and lateral compartments than male patients. These gender-specific differences in joint morphology may contribute to graft tear risk and outcomes of ACL reconstruction; however, comparative clinical studies are needed to confirm this possibility.

Level of evidence

3.

     

Improvement in the medial meniscus posterior shift following anterior cruciate ligament reconstruction

Purpose

Anterior cruciate ligament (ACL) reconstruction can reduce the risk of developing osteoarthritic knees. The goals of ACL reconstruction are to restore knee stability and reduce post-traumatic meniscal tears and cartilage degradation. A chronic ACL insufficiency frequently results in medial meniscus (MM) injury at the posterior segment. How ACL reconstruction can reduce the deformation of the MM posterior segment remains unclear. In this study, we evaluated the form of the MM posterior segment and anterior tibial translation before and after ACL reconstruction using open magnetic resonance imaging (MRI).

Methods

Seventeen patients who underwent ACL reconstructions without MM injuries were included in this study. MM deformation was evaluated using open MRI before surgery and 3 months after surgery. We measured medial meniscal length (MML), medial meniscal height (MMH), medial meniscal posterior body width (MPBW), MM–femoral condyle contact width (M-FCW) and posterior tibiofemoral distance (PTFD) at knee flexion angles of 10° and 90°.

Results

There were no significant pre- and postoperative differences during a flexion angle of 10°. At a flexion angle of 90°, MML decreased from 43.7 ± 4.5 to 41.4 ± 4.5 mm (P < 0.001), MMH from 7.5 ± 1.4 to 6.9 ± 1.4 mm (P = 0.006), MPBW from 13.1 ± 2.0 to 12.2 ± 1.9 mm (P < 0.001) and M-FCW from 10.0 ± 1.5 to 8.5 ± 1.5 mm (P < 0.001) after ACL reconstruction. The PTFD increased from 2.1 ± 2.8 to 2.7 ± 2.4 mm after ACL reconstruction (P = 0.015).

Conclusions

ACL reconstruction affects the contact pattern between the MM posterior segment and medial femoral condyle and can reduce the deformation of the MM posterior segment in the knee-flexed position by reducing abnormal anterior tibial translation. It possibly prevents secondary injury to the MM posterior segment and cartilage that progresses to knee osteoarthritis.

Level of evidence

IV.

     

Femoral intercondylar notch width size: a comparison between siblings with and without anterior cruciate ligament injuries

Purpose

Anterior cruciate ligament (ACL) injuries in siblings are commonly observed in the clinic. One, possibly genetic, factor contributing to the pathogenesis of sibling injuries may be narrow intercondylar notches, which are well recognized as predisposing to ACL injury. This study aimed primarily to: (1) assess the incidence of ACL injuries in siblings within an existing study cohort, (2) compare intercondylar notch width size in injured compared to matched uninjured control siblings and (3) compare the number of injured versus control sibling pairs sharing a narrow notch.

Methods

Twenty-four ACL-injured siblings from 10 families were matched for age, gender, family composition and sports activity, with 24 uninjured siblings from another 10 families. Intercondylar radiographs were taken to calculate anterior and posterior notch width indices (NWI). Notch size and the number of narrow notches in sibling pairs were compared between groups.

Results

Thirteen of 72 ACL-study participants had siblings with torn ACLs. Mean anterior NWI was 0.18 and 0.24 (p < 0.001), and mean posterior NWI was 0.26 and 0.3 (p = 0.006) for injured and uninjured siblings, respectively. Sixty percent of injured sibling pairs shared a narrow notch, while no uninjured sibling pairs did so (p = 0.003).

Conclusion

This study showed that siblings (and often sibling pairs) with injuries do have significantly narrower notches than those without. This could partly explain the prevalence of ACL injuries in siblings. To reduce ACL-injury rates, we advise that siblings of ACL-injured athletes with narrow notches, be radiologically screened, and if necessary, cautioned and counselled regarding preventative training.

Level of evidence

Case–control study, Level III.

     

Satisfactory outcomes following combined unicompartmental knee replacement and anterior cruciate ligament reconstruction

Purpose

There exist limited options for treatment of patients with combined medial compartment arthritis and anterior cruciate ligament (ACL) deficiency. Ideal treatment is one that offers lasting relief of symptoms not compromising any future surgery. Unicompartmental knee replacement has shown consistently good results in the relatively young and active population, but there is a high reported incidence of failure up to 20%, if performed in ACL-deficient knees. One of the recognized treatment modality is combined ACL reconstruction and unicompartmental arthroplasty. A systematic review was conducted looking at the demographics, techniques, complications and outcome of combined ACL reconstruction with unicompartmental knee arthroplasty.

Methods

A systematic literature search within the online Medline, PubMed Database, EMBASE, Web of Science, Cochrane and Google Scholar was carried out until October 2016 to identify relevant articles. A study was defined eligible if it met the following inclusion criteria: the surgical procedure combined unicompartmental knee arthroplasty and anterior cruciate ligament reconstruction; patient’s clinical and/or functional outcomes were reported; any complications intra-operatively and post-operatively were reported; and the full-text articles, written in English, German, Italian, Dutch or Spanish, were available. Quality and risk of bias assessments were done using standardized criteria set.

Results

A total of 8 studies met the inclusion criteria encompassing 186 patients who were treated with simultaneous ACL reconstruction and unicompartmental knee arthroplasty. The mean age was 50.5 years (range from 44 to 56) with a mean follow-up of 37.6 months (range from 24 to 60). There was an improvement in mean Oxford Score from 27.5 to 36.8. Complications reported included tibial inlay dislocation (n = 3), conversion to a total knee arthroplasty (n = 1), infection requiring two-stage revision (n = 2), deep-vein thrombosis (n = 1), stiffness requiring manipulation under anaesthesia (n = 1), retropatellar pain requiring arthroscopic adhesiolysis (n = 1).

Conclusion

Unicompartmental knee arthroplasty combined with ACL reconstruction can be a valid treatment option for selected patients, with combined medial unicompartmental knee osteoarthritis and ACL deficiency.

Level of evidence

Systematic Review of Level IV Studies, Level IV.

     

Lateral femoral notch depth is not associated with increased rotatory instability in ACL-injured knees: a quantitative pivot shift analysis

Purpose

A deep lateral femoral notch (LFN) on lateral radiographs is indicative of ACL injury. Prior studies have suggested that a deep LFN may also be a sign of persistent rotatory instability and a concomitant lateral meniscus tear. Therefore, the purpose of this study was to evaluate the relationship between LFN depth and both quantitative measures of rotatory knee instability and the incidence of lateral meniscus tears. It was hypothesized that greater LFN depth would be correlated with increased rotatory instability, quantified by lateral compartment translation and tibial acceleration during a quantitative pivot shift test, and incidence of lateral meniscus tears.

Methods

ACL-injured patients enrolled in a prospective ACL registry from 2014 to 2016 were analyzed. To limit confounders, patients were only included if they had primary ACL tears, no concurrent ligamentous or bony injuries requiring operative treatment, and no previous knee injuries or surgeries to either knee. Eighty-four patients were included in the final analysis. A standardized quantitative pivot shift test was performed pre-operatively under anesthesia in both knees, and rotatory instability, specifically lateral compartment translation and tibial acceleration, was quantified using tablet image analysis software and accelerometer sensors. Standard lateral radiographs and sagittal magnetic resonance images (MRI) of the injured knee were evaluated for LFN depth.

Results

There were no significant correlations between LFN depth on either imaging modality and ipsilateral lateral compartment translation or tibial acceleration during a quantitative pivot shift test or side-to-side differences in these measurements. Patients with lateral meniscus tears were found to have significantly greater LFN depths than those without on conventional radiograph and MRI (1.0 vs. 0.6 mm, p?<?0.05; 1.2 vs. 0.8 mm, p?<?0.05, respectively).

Conclusion

There was no correlation between lateral femoral notch depth on conventional radiographs or MRI and quantitative measures of rotatory instability. Concomitant lateral meniscus injury was associated with significantly greater LFN depth. Based on these findings, LFN depth should not be used as an indicator of excessive rotatory instability, but may be an indicator of lateral meniscus injury in ACL-injured patients.

Level of evidence

Prognostic level IV.

     

Timing of anterior cruciate ligament reconstruction within the first year after trauma and its influence on treatment of cartilage and meniscus pathology

Purpose

Anterior cruciate ligament (ACL) ruptures are often associated with primary meniscal and cartilage lesions. Late reconstruction of ACL-deficient knees may increase the risk of developing secondary meniscal and cartilage lesions; hence, the timing of ACL repair is of the utmost importance. Because meniscus outcome is also a potential predictor for osteoarthritis (OA), this study compared ACL repair within the first 6 months after injury to that of surgery conducted 7–12 months after injury with regard to the incidence of meniscal and cartilage lesions.

Methods

This prospective cross-sectional study included all complete isolated primary ACL ruptures treated in our institution within 1 year after trauma over a 12-month period. Exclusion criteria were revision ACL, complex ligament injuries, previous knee surgery, and missing injury data. Cartilage lesions were classified according to the score established by the International Cartilage Repair Society (ICRS score) and meniscal tears according to their treatment options.

Results

Two hundred and thirty-three of 730 patients (162 men, 71 women) with ACL repair met the inclusion criteria. 86.3 % of surgical interventions were conducted within 6 months and 13.7 % after 6 months of trauma. Severe cartilage lesions grade III–IV did not significantly differ between the different time points of ACL repair (<6 months 39.9 %; >6 months 31.3 %; p = n.s.). Medial meniscus lesions received significantly higher meniscal repair in early compared to delayed ACL repair. Significantly higher rate of meniscal repair of the medial meniscus was seen in cases of early ACL repair compared to delayed (<6 months 77.2 %, >6 months 46.7; p = 0.022). The rate of medial meniscal repair in early ACL repair was significantly higher for women (89.5–0 %; p = 0.002), however, not for men (73.3–53.8 %; p = n.s.). No differences were found for lateral meniscal lesions, with regard to neither the different time points (p = n.s.) nor the sex (p = n.s.).

Conclusions

Because of the significantly higher rate of prognostically advantageous meniscal repair, the recommendation for an ACL reconstruction within 6 months after trauma was made to preserve the meniscus and reduce the risk of developing OA.

Level of evidence

Prospective cross-sectional cohort study, Level II.

     

Effect of meniscal loss on knee stability after single-bundle anterior cruciate ligament reconstruction

Purpose

The menisci are known to be important secondary constraints to anterior translation of the tibia in the ACL-deficient knee. The effect of meniscal loss on knee stability as measured by the magnitude of the pivot shift following ACL reconstruction is unknown. The objective of this investigation was to determine the effect of meniscectomy on knee stability following two single-bundle ACL reconstruction strategies.

Materials and Methods

A mechanized pivot shift was performed on cadaveric specimens in the ACL-intact and ACL-deficient state. Tibiofemoral translation was recorded using a surgical navigation system. The ACL was reconstructed utilizing a nonanatomic graft (n = 10) extending from the posterolateral tibial footprint to the anteromedial femoral footprint, or an anatomic anteromedial single-bundle graft extending from the anteromedial tibial footprint to the anteromedial femoral footprint (n = 10) and testing repeated. The medial or lateral meniscus was sectioned and the examination repeated. The other meniscus was sectioned and the examination subsequently repeated.

Results

Lateral compartment translation during the pivot shift was significantly reduced following anatomic ACL reconstruction. In the nonanatomic group, lateral compartment translation increased by 9.1 mm (P < 0.001) after unicomparmental meniscectomy and 11.5 mm (P < 0.001) after bicompartmental meniscectomy. In the anatomic reconstruction group, lateral compartment translation increased by 7.6 mm (P < 0.001) after bicompartmental meniscectomy.

Conclusion

With isolated ACL injury, anatomic single-bundle ACL reconstruction controlled the pivot shift during time zero testing. However, significant increases in lateral compartment translation during the pivot shift are seen following bicompartmental meniscectomy. Nonanatomic ACL reconstruction was less effective in controlling the pivot shift at time zero testing, and significant increases in lateral compartment translation during the pivot shift were seen following both unicomparmental and bicompartmental meniscectomy.