Comparison of T1rho relaxation times between ACL-reconstructed knees and contralateral uninjured knees

Purpose

The goal of this study is to compare the cartilage of anterior cruciate ligament (ACL)-reconstructed and uninjured contralateral knees using T _1ρ MRI 12–16 months after ACL reconstructions.

Methods

Eighteen patients with ACL-reconstructed knees (10 women, 8 men, mean age = 38.3 ± 7.8 years) were studied using 3T MRI. Injured and contralateral knee MR studies were acquired 12–16 months post-operatively. Cartilage sub-compartment T _1ρ values of each injured knee were compared with the contralateral knee’s values. Subgroup analysis of sub-compartment T _1ρ values in both knees was performed between patients with and without meniscal tears at the time of ACL reconstruction using a paired Student’s t test.

Results

In ACL-injured knees, the T _1ρ values of the medial tibia (MT) and medial femoral condyle (MFC) were significantly elevated at 12–16 months follow-up compared to contralateral knees. Patients with a medial meniscal tear had higher MFC and MT T _1ρ values compared to respective regions in contralateral knees. Patients with lateral meniscal tears had higher lateral femoral condyle and LT T _1ρ values compared to respective regions in contralateral knees. There were no differences between the injured and contralateral knees of patients without meniscal tears.

Conclusions

T _1ρ MRI can detect significant changes in the medial compartments’ cartilage matrix of ACL-reconstructed knees at 1 year post-operatively compared to contralateral knees. The presence of a meniscal tear at the time of ACL reconstruction is a risk factor for cartilage matrix degeneration in the femorotibial compartments on the same side as the meniscal tear.     

Optimal measurement of clinical rotational test for evaluating anterior cruciate ligament insufficiency

Purpose

Rotational instability in ACL insufficient knee addresses the symptom or the abnormal motion which can be reproduced and subjectively evaluated in the clinical exam. Clinically available quantitative measurement for this instability has not been established due to mixed testing maneuvers and complex kinematics. The purpose was to measure knee kinematics during three manually performed rotational tests and to determine the optimal method to detect the abnormality in ACL deficient knees.

Method

Thirteen unilateral ACL deficient patients were tested by internal and external pure rotational stress tests and pivot shift test under anesthesia before scheduled ACL reconstructions. Rotation and coupled motion, i.e., tibial anteroposterior translation, were measured using an electromagnetic measurement system. Additionally, the acceleration of the tibial posterior translation during pivot shift test was calculated. The differences of these parameters between ACL intact and deficient knees were tested.

Results

Knee rotation is not different between ACL intact and deficient during both pure rotational stress test and pivot shift test. The coupled anterior tibial translation during pivot shift test was significantly different between ACL intact, 13.5?±?4.1?mm, and deficient knees, 23.1?±?4.4?mm, (P?<?0.01) as well as the acceleration of the tibial posterior translation (1.1?±?0.4?m/sec² in intact knees, 3.2?±?1.5?m/sec² in deficient knees; P?<?0.01). The coupled motion during pure rotational stress tests was similar regardless of ACL condition.

Conclusion

The rotational instability of the ACL deficiency was reproduced only by the pivot shift test and detected only by measuring the tibial anteroposterior translation and acceleration of the tibial posterior reduction. Level of evidence Diagnostic study, Level III.     

Non-traumatic anterior cruciate ligament abnormalities and their relationship to osteoarthritis using morphological grading and cartilage T2 relaxation times: data from the Osteoarthritis Initiative (OAI)

Objectives

The aim of this work was to study anterior cruciate ligament (ACL) degeneration in relation to MRI-based morphological knee abnormalities and cartilage T₂ relaxation times in subjects with symptomatic osteoarthritis.

Methods

Two radiologists screened the right knee MRI of 304 randomly selected participants in the Osteoarthritis Initiative cohort with symptomatic OA, for ACL abnormalities. Of the 52 knees with abnormalities, 28 had mucoid degeneration, 12 had partially torn ACLs, and 12 had completely torn ACLs. Fifty-three randomly selected subjects with normal ACLs served as controls. Morphological knee abnormalities were graded using the WORMS score. Cartilage was segmented and compartment-specific T₂ values were calculated.

Results

Compared to normal ACL knees, those with ACL abnormalities had a greater prevalence of, and more severe, cartilage, meniscal, bone marrow, subchondral cyst, and medial collateral ligament lesions (all p?2 measurements did not significantly differ by ACL status.

Conclusions

ACL abnormalities were associated with more severe degenerative changes, likely because of greater joint instability. T2 measurements may not be well suited to assess advanced cartilage degeneration.     

Relationship of native tibial plateau anatomy with stability testing in the anterior cruciate ligament-deficient knee

Purpose

Recent attention has been drawn to tibial plateau slope and depth with relation to both risk of anterior cruciate ligament (ACL) tear and kinematics in the cruciate-deficient knee. The purpose was to evaluate the relationship between native proximal tibial anatomy and knee kinematics in the anterior cruciate-deficient knee.

Methods

Twenty-two cadaveric knees underwent CT scanning to measure proximal tibia anatomy. Translation was measured during Lachman and mechanized pivot-shift tests on the intact knee and then after resection of the ACL. Pearson’s correlation was calculated to assess the relationship between tibial translation of the ACL-deficient knee and tibial plateau anatomic parameters.

Results

No significant correlation was found between ACL-deficient kinematic testing and tibial slope or depth (n.s.). Lateral compartment translation on Lachman and pivot-shift testing correlated with lateral compartment AP length (P?=?0.007 and P?=?0.033, respectively). The ratio of lateral AP length to medial AP length correlated with lateral compartment translation during the pivot shift (P?=?0.002).

Conclusion

There was a poor correlation between native tibial slope and kinematic testing. There were, however, increases in translation during pivot-shift and Lachman testing with increased AP length of the lateral compartment. In addition, the finding of increased pivot-shift magnitude when the lateral compartment was relatively wide in the AP plane compared to the medial compartment suggests that patients with a “dominant” lateral compartment may be prone to a greater magnitude of instability after ACL injury.     

Symptomatic mucoid degeneration of the anterior cruciate ligament

Purpose

Mucoid degeneration of the anterior cruciate ligament (ACL) is a little-known entity. The aim of this study was to detail the clinical, radiological, arthroscopic and pathological findings of this condition and to report clinical outcomes following arthroscopic partial excision of the ACL.

Methods

Between 1999 and 2009, 80 knees in 78 patients were diagnosed as having mucoid degeneration of the ACL based on MRI and clinical findings, and subsequently underwent arthroscopic treatment. Of these, 68 knees in 66 patients, with a median age of 51 years (range, 35–75 years), were followed-up for at least one year.

Results

All patients had insidious onset of knee pain, while 56 knees (82 %) had associated extension deficits and 36 knees (53 %) had restricted flexion. MRI findings typically showed diffuse thickening and increased signal intensity of the ACL. Arthroscopic examination revealed notch impingement and bulging of hypertrophied ACL into lateral compartments. Associated lesions included meniscal tears in 33 knees and chondral lesions of at least Outerbridge grade 2 in 56 knees. All knees underwent arthroscopic partial excision of the hypertrophied ACL, with three undergoing preoperative and 30 undergoing concomitant meniscectomies. Pain relief was achieved in 58 of 62 knees (94 %) following partial excision of the ACL. Extension deficits were normalized in 49 of 56 knees (88 %), and restricted flexion was normalized in 33 of 36 affected knees (92 %). Four knees of four patients had postoperative symptoms of anterior instability.

Conclusions

Pain and limitation of motion due to mucoid degeneration of the ACL can be improved by arthroscopic partial excision of the ACL with or without notchplasty. However, one potential complication is the development of postoperative symptoms of anterior instability.

Level of evidence

Retrospective study, Level IV.     

Anatomic ACL reconstruction produces greater graft length change during knee range-of-motion than transtibial technique

Purpose

Because distance between the knee ACL femoral and tibial footprint centrums changes during knee range-of-motion, surgeons must understand the effect of ACL socket position on graft length, in order to avoid graft rupture which may occur when tensioning and fixation is performed at the incorrect knee flexion angle. The purpose of this study is to evaluate change in intra-articular length of a reconstructed ACL during knee range-of-motion comparing anatomic versus transtibial techniques.

Methods

After power analysis, seven matched pair cadaveric knees were tested. The ACL was debrided, and femoral and tibial footprint centrums for anatomic versus transtibial techniques were identified and marked. A suture anchor was placed at the femoral centrum and a custom, cannulated suture-centring device at the tibial centrum, and excursion of the suture, representing length change of an ACL graft during knee range-of-motion, was measured in millimeters and recorded using a digital transducer.

Results

Mean increase in length as the knee was ranged 120°–0° (full extension) was 4.5 mm (±2.0 mm) for transtibial versus 6.7 mm (±0.9 mm) for anatomic ACL technique. A significant difference in length change occurs during knee range-of-motion both within groups and between the two groups.

Conclusions

Change in length of the ACL intra-articular distance during knee range-of-motion is greater for anatomic socket position compared to transtibial position. Surgeons performing anatomic single-bundle ACL reconstruction may tension and fix grafts with the knee in full extension to minimize risk of graft stretch or rupture or knee capture during full extension. This technique may also result in knee anterior–posterior laxity in knee flexion.     

Internal tibial rotation during in vivo, dynamic activity induces greater sliding of tibio-femoral joint contact on the medial compartment

Purpose

Although extensive research has been conducted on rotational kinematics, the internal/external rotation of the tibio-femoral joint is perhaps less important for protecting joint health than its effect on joint contact mechanics. The purpose of this study was to evaluate tibio-femoral joint contact paths during a functional activity (running) and investigate the relationship between these arthrokinematic measures and traditional kinematics (internal/external rotation).

Methods

Tibio-femoral motion was assessed for the contralateral (uninjured) knees of 29 ACL-reconstructed individuals during downhill running, using dynamic stereo X-ray combined with three-dimensional CT bone models to produce knee kinematics and dynamic joint contact paths. The joint contact sliding length was estimated by comparing femoral and tibial contact paths. The difference in sliding length between compartments was compared to knee rotation.

Results

Sliding length was significantly larger on the medial side (10.2?±?3.8?mm) than the lateral side (2.3?±?4.0?mm). The difference in sliding length between compartments (mean 7.8?±?3.0?mm) was significantly correlated with internal tibial rotation (P?R ²?=?0.74).

Conclusion

The relationship between rotational knee kinematics and joint contact paths was specifically revealed as greater tibial internal rotation was associated with larger magnitude of sliding motion in the medial compartment. This could suggest that lateral pivot movement occurs during running.

Clinical relevance

Rotational kinematics abnormality should be treated for restoring normal balance of joint sliding between medial and lateral compartments and preventing future osteoarthritis.

Level of evidence

Prognostic studies, Level II.     

The accuracy of bone tunnel position using fluoroscopic-based navigation system in anterior cruciate ligament reconstruction

Purpose

The first purpose of this study was to examine whether fluoroscopic-based navigation system contributes to the accuracy and reproducibility of the bone tunnel placements in single-bundle anterior cruciate ligament (ACL) reconstruction. The second purpose was to investigate the application of the navigation system for double-bundle ACL reconstruction.

Methods

A hospital-based case–control study was conducted, including a consecutive series of 55 patients. In 37 patients who received single-bundle ACL reconstruction, surgeries were performed with this system for 19 knees (group 1) and without this system for 18 knees (group 2). The positioning of the femoral and tibial tunnels was evaluated by plain sagittal radiographs. In 18 patients who received double-bundle ACL reconstruction using the navigation system (group 3), the bone tunnel positions were assessed by three-dimensional computed tomography (3D-CT). Clinical assessment of all patients was followed with the use of Lysholm Knees Score and IKDC.

Results

Taking 0% as the anterior and 100% as the posterior extent, the femoral tunnels were 74.9?±?3.0% in group 1 and 71.5?±?5.8% in group 2 along Blumensaat’s line, and the tibial tunnels were 42.3?±?1.4% in group 1 and 42.5?±?4.6% in group 2 along the tibia plateau. The bone tunnel positions in group 1 were located significantly closer to the position planned preoperatively and varied less in both femur and tibial side, compared with those without navigation (group 2). (Femur: P?P?Conclusion The fluoroscopic-based navigation system contributed to the more reproducible placement of the bone tunnel during single-bundle ACL reconstruction compared with conventional technique. Additionally, this device was also useful for double-bundle ACL reconstruction.

Level of evidence

Case–control study, Therapeutic study, Level III.     

Case–control study to estimate the performance of dual-energy computed tomography for anterior cruciate ligament tears in patients with history of knee trauma

Objective

Computed tomography (CT) is used to assess for fracture after knee trauma, but identification of ligamentous injuries may also be beneficial. Our purpose is to assess the potential of dual-energy computed tomography (DECT) for the detection of complete anterior cruciate ligament (ACL) disruption.

Methods

Sixteen patients with unilateral traumatic ACL disruption (average of 58 days following trauma) confirmed by MRI, and 11 control patients without trauma, underwent DECT of both knees. For each knee, axial, sagittal, and oblique sagittal images (with DECT bone removal, single-energy (SE) bone removal, and DECT tendon-specific color mapping) were reconstructed. Four musculoskeletal radiologists randomly evaluated the 324 DECT reconstructed series (54 knees with 6 displays) separately, to assess for ACL disruption using a five-point scale (1?=?definitely not torn, to 5?=?definitely torn). ROC analysis was used to compare performance across readers and displays.

Results

Sagittal oblique displays (mixed kV soft tissue, SE bone removal, and DECT bone removal) demonstrated higher areas under the curve for ACL disruption (AUC?=?0.95, 0.93 and 0.95 respectively) without significant differences in performance between readers (p?>?0.23). Inter-reader agreement was also better for these display methods (ICC range 0.62–0.69) compared with other techniques (ICC range 0.41–0.57). Mean sensitivity for ACL disruption was worst for DECT tendon-specific color map and axial images (24 % and 63 % respectively).

Conclusion

DECT knee images with oblique sagittal reconstructions using either mixed??kV or bone removal displays (either DECT or SE) depict ACL disruption in the subacute or chronic setting with reliable identification by musculoskeletal radiologists.     

Evaluating rotational kinematics of the knee in ACL-ruptured and healthy patients using 3.0 Tesla magnetic resonance imaging

Purpose

Rotational knee laxity is an important measure in restoring knee stability following anterior cruciate ligament (ACL) injury, but is difficult to quantify with current clinical tools. The hypothesis of the study is that there is greater tibial rotation (TR) in women than men, and also in ACL-deficient than healthy knees.

Methods

Sixteen healthy (8 men, 26.8?±?6.4?years; 8 women, 26.9?±?3.8?years) and ten ACL-deficient (5 men, 33.6?±?10.5?years; 5 women, 36.3?±?10.7?years) subjects received bilateral knee MRI in 15° of flexion using a custom device to apply a constant axial compressive load (44?N). A rotational torque (3.35?Nm) was sequentially applied to obtain images at internal and external rotation positions. T ₂-weighted images were acquired in internal and external rotation. Images were segmented and TR was calculated. To assess reproducibility, six knees were scanned twice on separate days. Group comparisons were made with unpaired t tests, while intrasubject comparisons were made using paired t tests.

Results

Healthy women demonstrated greater TR than men (13.6°?±?4.7° vs. 8.3°?±?3.6°; P?=?0.001). Male ACL-deficient knees showed greater TR than the contralateral knee (15.7°?±?6.9° vs. 7.7°?±?5.6°; P?=?0.003), and compared to male controls (P?=?0.002). ACL-deficient women showed greater TR compared to their contralateral leg (15.1°?±?2.3° vs. 10.0°?±?4.3°; P?=?0.01). The intraclass correlation coefficient of the TR measurement was 0.913, and the SEM?=?1.1°.

Conclusions

Kinematic MRI is a reproducible method to quantify total knee rotation. Women have more rotational laxity than men, particularly in the external rotation position. ACL rupture leads to increased rotational laxity of the knee.

Level of evidence

Retrospective case–control series, Level III.     

Roles of ACL remnants in knee stability

Purpose

This study evaluated knee laxity in anterior tibial translation and rotation following removal of anterior cruciate ligament (ACL) remnants using a computer navigation system.

Methods

This prospective study included 50 knees undergoing primary ACL reconstruction using a navigation system. ACL remnants were classified into four morphologic types: Type 1, bridging between the roof of the intercondylar notch and tibia; Type 2, bridging between the posterior cruciate ligament and tibia; Type 3, bridging between the anatomical insertions of the ACL on the lateral wall of the femoral condyle and the tibia; and Type 4, no bridging of ACL remnants. Anterior tibial translation and rotatory laxity were measured before and after remnant resection using a navigation system at 30°, 60°, and 90° of knee flexion. The amount of change in anterior tibial translation and rotatory laxity of each type was compared among the types.

Results

The different morphologic types of ACL remnants were as follows: Type 1, 15 knees; Type 2, 9 knees; Type 3, 6 knees; and Type 4, 20 knees. The amount of change in anterior tibial translation and rotatory laxity at 30° knee flexion in Type 3 was significantly larger than in the other types. There were no significant differences in either tibial translation or rotatory laxity at 60° and 90° knee flexion among the types.

Conclusions

In Type 3, ACL remnants contributed to anteroposterior and rotatory knee laxity evaluated at 30° knee flexion. The bridging point of the remnants is important to knee laxity. The Type 3 remnant should be preserved as much as possible when ACL reconstruction surgery is performed.

Level of evidence

Prognostic study, Level II.     

No difference in survivorship after unicompartmental knee arthroplasty with or without an intact anterior cruciate ligament

Purpose

Anterior cruciate ligament deficiency (ACLD) has been considered a contraindication for Oxford unicompartmental knee arthroplasty (UKA) because of the reported higher incidence of failure when implanted in ACLD knees. However, given the potential advantages of UKA over total knee arthroplasty (TKA), we have performed UKA in a limited number of patients with ACL deficiency and end-stage medial compartment osteoarthritis (OA) over the past 11 years. The primary aim of this study was to establish the clinical outcome of this cohort; the secondary aim was to compare both clinical and radiographic data with a matched cohort of ACL-intact (ACLI) patients who have undergone UKA for anteromedial OA.

Methods

This retrospective observational study describes the clinical and radiological outcome in 46 medial Oxford UKAs implanted in 42 consecutive patients with ACL deficiency and concomitant symptomatic medial compartment OA at mean follow-up of 5 years. It also compares the outcomes with a matched cohort of UKA patients with an intact ACL (ACLI group).

Results

At the time of last follow-up, there was no significant difference in clinical results or survivorship between the two groups in this study.

Conclusion

The successful short-term results of the ACLD group suggest ACL deficiency may not always be a contraindication to Oxford UKA as previously thought. Until long-term data is available, however, we maintain our recommendation that ACLD be considered a contraindication.

Level of evidence

III.     

An isolated rupture of the posterior cruciate ligament results in reduced preoperative knee function in comparison with an anterior cruciate ligament injury

Purpose

To investigate differences in preoperative knee function (Knee Injury and Osteoarthritis Outcome Score, KOOS), the time period from injury to surgery, and associated injuries when comparing primary isolated posterior cruciate ligament (PCL) and primary anterior cruciate ligament (ACL) reconstructions.

Methods

Isolated primary ACL and PCL reconstructions registered in the Norwegian National Knee Ligament Registry from 2004 through 2010 were included (n = 71 primary PCLs and 9,649 primary ACLs). Linear regression analysis was used to evaluate the preoperative KOOS subscale values.

Results

The preoperative KOOS in the PCL group (n = 71) and ACL group (n = 9,649) was significantly different for the subscales symptoms (mean difference, ?8.4; 95 % CI: ?12.8 to ?4.0), pain (mean difference, ?15.9; 95 % CI: ?20.3 to ?11.4), activities of daily living (mean difference, ?12.9; 95 % CI: ?17.4 to ?8.4), sport and recreation (mean difference, ?15.9; 95 % CI: ?22.6 to ?9.3), and quality of life (mean difference, ?7.9; 95 % CI: ?12.4 to ?3.5). The primary isolated PCL-reconstructed knees had a median time from injury to surgery of 21 months in comparison with 8 months for ACL injuries. The ACL-injured knees had more associated injuries (meniscus and full-thickness cartilage lesions) than the PCL-injured knees.

Conclusion

Surgically treated knees with an isolated rupture of the PCL exhibited worse knee function preoperatively compared with knees with an isolated ACL injury; in addition, the delay to surgery was longer. Meniscal lesions were found more frequently in ACL-injured knees.

Level of evidence

Prospective cohort study, evidence Level I.     

Anterior cruciate ligament bundle measurement by MRI

Objective

An accurate in vivo method of measuring dimensions of the anteromedial (AM) and posterolateral (PL) anterior cruciate ligament (ACL) bundles has not been established. The purpose of this study was to measure each individual bundle using double oblique axial MR imaging of the ACL, to compare this with cadaveric measurements, and to investigate the range of measurements seen in normal subjects.

Materials and methods

In five cadaveric knees, measurements obtained of the proximal, middle, and distal segments of each ACL bundle from double oblique axial MR images were compared with direct measurements following anatomical dissection. Thereafter, the size of both bundles from 24 normal knees was measured using an identical MR technique. Inter-observer variation was calculated using intraclass correlation.

Results

ACL bundle measurement in the cadaveric knees had a strong correlation (r?=?0.93) with measurements obtained following anatomical dissection. No significant difference existed between measurements obtained from cadaveric knees and living normal subjects (p?>?0.05). Interobserver correlation for MR measurements was excellent (R?=?0.92–0.93). Overall, the long and short axis of the AM bundle were significantly larger than those of the PL bundle (p?<?0.05). Also, men showed significantly larger AM and PL bundles than women (p?<?0.05). Bundle size was not related to age or knee dominance.

Conclusion

The individual ACL bundles can be accurately measured on double oblique axial MR imaging. The AM bundle is larger in caliber than the PL bundle. Both bundles are larger in men than in women and there is no significant side-to side difference.     

Long-term follow-up of ACL reconstruction with hamstring autograft

Purpose

To investigate the differences in the incidence and severity of knee osteoarthritis (OA), joint space narrowing, knee laxity, and knee flexion and extension strength between an anterior cruciate ligament (ACL)-reconstructed knee and the contralateral non-reconstructed limb.

Methods

Retrospective case series of patients from a single surgeon that had an ACL reconstruction with a semitendinosus/gracilis autograft more than 12 years ago. Outcome measures included radiographic analysis, International Knee Documentation Committee Subjective Knee Evaluation Form (IKDC), KT-1000, Tegner Activity Level Scale, Lysholm Knee Score, ACL quality of life score (ACL-QOL) and knee flexor/extensor strength.

Results

Seventy-four patients consented and sixty-eight (43 male, 25 female) were included for analysis. Average age (SD) at the time of surgery was 31.2 (±9.1) years. At follow-up of 14.6 (1.9) years, 9 % had re-ruptured their ACL, whereas 5 % ruptured the contralateral ACL. Reconstructed knees had a greater incidence and severity of OA (P < 0.01). Medial meniscus surgery was a strong predictor of OA. Seventy-five per cent scored a normal or nearly normal knee on the IKDC. The mean Lysholm score was 75.8 % and Tegner Activity Level Scale scores decreased (P < 0.001) from the time of surgery. Knee extension strength was greater in the contralateral knee at speeds of 60°/s (P = 0.014) and 150°/s (P = 0.012).

Conclusions

Reconstructed knees have a greater incidence and severity of OA than non-reconstructed knees, which suggests degenerative changes are secondary to ACL rupture. Medial meniscus surgery is a strong predictor of OA. Despite this, 75 % of patients reported good outcomes.     

Anteromedial versus central single-bundle graft position: which anatomic graft position to choose?

Purpose

To compare the time-zero stability of an anatomic anteromedial (AM) single-bundle ACL reconstruction to an anatomic central (CTR) single-bundle ACL reconstruction.

Methods

Twelve (6 paired) hip to knee cadaveric specimens were studied. Using custom ACL computer navigation software, a Lachman test and a previously validated, navigated mechanized pivot shift test were performed on 4 separate experimental groups in each specimen: (1) intact ACL, (2) ACL deficient with total medial and lateral meniscectomy, (3) following anatomic AM single-bundle ACL reconstruction, and (4) after anatomic CTR single-bundle ACL reconstruction. Maximum anterior tibial translation in each group was measured.

Results

Lachman: No significant difference was observed between the AM and CTR reconstructions (n.s.) or between reconstruction and the intact ACL (3.4?±?1.7?mm) (n.s.). Pivot Shift: Both the AM and CTR ACL reconstructions significantly reduced anterior translation relative to the ACL/menisci-deficient condition (lateral compartment: 8.9?±?3.8 mm and 6.75?±?4.6 mm vs. 17.25?±?3.5?mm, respectively; P?P?P?P?Conclusions It has been shown that there was no difference in the time-zero biomechanical stability between an anatomic anteromedial and anatomic central single-bundle ACL reconstruction. Given the current debate on the best anatomic ACL reconstruction technique, anatomic socket position in either the anteromedial or central locations provides similar time-zero biomechanics.     

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.

     

Arthroscopic evaluation of knee lateral compartment widening after lateral ligamentous injury

Purpose

To evaluate whether diagnostic arthroscopy of the lateral tibiofemoral compartment can determine the presence of a lateral ligamentous knee injury.

Methods

Nine cadaveric knee specimens were used with varus stresses of 12 Nm and the force at which no further lateral opening occurred. Arthroscopic measurements were taken of the lateral compartments with knees at 30°, 45° and 90°. Measurements were recorded in the intact knees and with sequential sectioning of LCL, popliteus, popliteofibular, ACL and PCL. Measurements and opening differences between each ligament state were recorded.

Results

No significant difference existed between the two forces compared (p < 0.05). There was a significant difference in opening distance measured at all knee angles with sequential sectioning (p < 0.001). Sequential opening difference between each ligament state was significantly different (p < 0.001) and also when compared across each knee angle (p < 0.001). At 30° for an isolated LCL injury, the average lateral opening was 10.1 mm. For a combined LCL and PLC (popliteus tendon and popliteofibular ligament) injury, the average lateral opening was 12.9 mm. For LCL-, PLC- and ACL-deficient knees, there was average lateral opening of 16.5 mm.

Conclusions

LCL and combined lateral ligamentous injuries can be differentiated during arthroscopy with varus stress. This may be useful when deciding if there is a need for operative repair of any injured lateral ligamentous structures.     

ACL–PCL and intercondylar notch impingement: magnetic resonance imaging of native and double-bundle ACL-reconstructed knees

Purpose

The purpose of this study was to: (1) define the relationship between the ACL and PCL in normal knees; (2) determine whether ACL–PCL impingement occurs in native knees; and (3) determine whether there is a difference in impingement between double-bundle reconstructed and native knees.

Methods

Eight subjects were identified (age 20–50; 6 females, 2 males). All were at least 1-year status postanatomic double-bundle ACL reconstruction (allograft; AM = 8 mm; PL = 7 mm) and had no history of injury or surgery to the contralateral knee. MRIs of both knees were performed with the knee at 0 and 30° of flexion. The images were evaluated by a non-treating surgeon and two musculoskeletal radiologists. Coronal and sagittal angles of AM and PL bundles, Liu’s PCL index and the distance between ACL and PCL on modified axial oblique images were recorded. Impingement was graded (1) no contact; (2) contact without deformation; or (3) contact and distortion of PCL contour.

Results

Seventy-five percent (6) of the native ACL’s showed no contact with the roof of the intercondylar notch or PCL, compared to 25 % (2) of the double-bundle reconstructed ACLs. One double-bundle reconstructed ACL showed intercondylar notch roof and ACL–PCL impingement (12.5 %). Significant differences were found between the native ACL and the double-bundle reconstructed ACL for the coronal angle of the AM (79° vs. 72°, p = 0.002) and PL bundle (75° vs. 58°, p = 0.001). No differences in ROM or stability were noted at any follow-up interval between groups based on MRI impingement grade.

Conclusion

ACL–PCL contact occurred in 25 % of native knees. Contact between the ACL graft and PCL occurred in 75 % of double-bundle reconstructed knees. ACL–PCL impingement, both contact and distortion of the PCL, occurred in one knee after double-bundle reconstruction. This study offers perspective on what can be considered normal contact between the ACL and PCL and how impingement after ACL reconstruction can be detected on MRI.

Level of evidence

Cohort Study, Level III.