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.

     

Anterolateral ligament abnormalities in patients with acute anterior cruciate ligament rupture are associated with lateral meniscal and osseous injuries

Objective

To determine the frequency of anterolateral ligament (ALL) injury in patients with acute anterior cruciate ligament (ACL) rupture and to analyse its associated injury patterns.

Methods

Ninety patients with acute ACL rupture for which MRI was obtained within 8 weeks after the initial trauma were retrospectively identified. Two radiologists assessed the status of the ALL on MRI by consensus. The presence or absence of an ALL abnormality was compared with the existence of medial and lateral meniscal tears diagnosed during arthroscopy. Associated collateral ligament and osseous injuries were documented with MRI.

Results

Forty-one of 90 knees (46 %) demonstrated ALL abnormalities on MRI. Of 49 knees with intact ALL, 15 (31 %) had a torn lateral meniscus as compared to 25 torn lateral menisci in 41 knees (61 %) with abnormal ALL (p?=?0.008). Collateral ligament (p?≤?0.05) and osseous injuries (p?=?0.0037) were more frequent and severe in ALL-injured as compared with ALL-intact knees.

Conclusion

ALL injuries are fairly common in patients with acute ACL rupture and are statistically significantly associated with lateral meniscal, collateral ligament and osseous injuries.

Key Points

? ALL injuries are fairly common in patients with acute ACL rupture. ? ALL injuries are highly associated with lateral meniscal and osseous injuries. ? MRI assessment of ACL-injured knees should include evaluation of the ALL.

     

Diminished femoral head–neck offset and the restricted hip range of motion suggesting a possible role in ACL injuries

Purpose

Femoroacetabular impingement may be associated with anterior cruciate ligament (ACL) injuries. The purpose of this study was to determine the head–neck offset, as measured by 45° Dunn’s view alpha angles, in patients with ACL injuries compared to control subjects.

Methods

In this retrospective study, 140 consecutive non-professional athletes with primary ACL ruptures confirmed with knee arthroscopy and 100 consecutive patients with non-ACL injury were enrolled. Hip range of motion was assessed in lower extremities in all participants, and alpha angle was calculated according to 45° Dunn’s view radiographs.

Results

There is not any difference in age, gender distribution, height, weight, and BMI between groups. Internal rotation, abduction, and adduction of the hip were significantly decreased in ACL-injured patients comparing with control subjects (p < 0.001). ACL-injured patients had also a significantly higher alpha angle comparing to the control individuals (p < 0.001). The mean of alpha angle in the ACL-injured patients was 56.1 (SD 10.1) and in the non-ACL-injured group was 49.3 (SD 9.4).

Conclusions

The patients in ACL-injured group showed a significant restriction in hip range of motion and also a diminished femoral head–neck offset suggesting a possible role of these findings in the outcome assessed.

Level of evidence

III.

     

No negative effect on patient-reported outcome of concomitant cartilage lesions 5–9 years after ACL reconstruction

Purpose

To compare patient-reported outcome 5–9 years after anterior cruciate ligament (ACL) reconstruction in patients with and without a concomitant full-thickness [International Cartilage Repair Society (ICRS) grade 3–4] cartilage lesion.

Methods

This is a prospective follow-up of a cohort of 89 patients that were identified in the Norwegian National Knee Ligament Registry and included in the current study in 2007, consisting of 30 primary ACL-reconstructed patients with a concomitant, isolated full-thickness cartilage lesion (ICRS grade 3 and 4) and 59 matched controls without cartilage lesions (ICRS grade 1–4). At a median follow-up of 6.3 years (range 4.9–9.1) after ACL reconstruction, 74 (84 %) patients completed the Knee Injury and Osteoarthritis Outcome Score (KOOS), which was used as the main outcome measure. Secondary outcomes included radiographic evaluation according to the Kellgren–Lawrence criteria of knee osteoarthritis (OA).

Results

At follow-up, 5–9 years after ACL reconstruction, no statistically significant differences in KOOS were detected between patients with a concomitant full-thickness cartilage lesion and patients without concomitant cartilage lesions. Radiographic knee OA of the affected knee, defined as Kellgren and Lawrence ≥2, was significantly more frequent in subjects without a concomitant cartilage lesion (p = 0.016).

Conclusion

ACL reconstruction performed in patients with an isolated concomitant full-thickness cartilage lesion restored patient-reported knee function to the same level as ACL reconstruction performed in patients without concomitant cartilage lesions, 5–9 years after surgery. This should be considered in the preoperative information given to patients with such combined injuries, in terms of the expected outcome after ACL reconstruction and in the counselling and decision-making on the subject of surgical treatment of the concomitant cartilage lesion.

Level of evidence

Prognostic; prospective cohort study, Level I.

     

Two-dimensional motion analysis of dynamic knee valgus identifies female high school athletes at risk of non-contact anterior cruciate ligament injury

Purpose

Female athletes are at greater risk of non-contact ACL injury. Three-dimensional kinematic analyses have shown that at-risk female athletes have a greater knee valgus angle during drop jumping. The purpose of this study was to evaluate the relationship between knee valgus angle and non-contact ACL injury in young female athletes using coronal-plane two-dimensional (2D) kinematic analyses of single-leg landing.

Methods

Two hundred ninety-one female high school athletes newly enrolled in basketball and handball clubs were assessed. Dynamic knee valgus was analysed during single-leg drop jumps using 2D coronal images at hallux–ground contact and at maximal knee valgus. All subjects were followed up for 3 years for ACL injury. Twenty-eight (9.6%) of 291 athletes had ACL rupture, including 27 non-contact ACL injuries. The injured group of 27 knees with non-contact ACL injury was compared with a control group of 27 randomly selected uninjured knees. The relationship between initial 2D movement analysis results and subsequent ACL injury was investigated.

Results

Dynamic knee valgus was significantly greater in the injured group compared to the control group at hallux–ground contact (2.1 ± 2.4 vs. 0.4 ± 2.2 cm, P = 0.006) and at maximal knee valgus (8.3 ± 4.3 vs. 5.1 ± 4.1 cm, P = 0.007).

Conclusion

The results of this study confirm that dynamic knee valgus is a potential risk factor for non-contact ACL injury in female high school athletes. Fully understanding the risk factors that increase dynamic knee valgus will help in designing more appropriate training and interventional strategies to prevent injuries in at-risk athletes.

Level of evidence

Prognostic studies, Level II.

     

Acute chondrocyte response to controlling joint instability in an osteoarthritis rat model

Objective

Osteoarthritis is a common consequence of anterior cruciate ligament (ACL) injury. Joint instability induced by ACL transection is involved in the chondrocyte response in the articular cartilage degeneration process. The aim of this study was to confirm the effect of controlling joint instability after ACL injury by investigating the chondrocyte reaction in the early osteoarthritic disease process.

Methods

For inducing different joint conditions (stability and instability), 15 Wistar rats were randomized into three groups: ACL transection with joint instability (ACL-T, n = 5), controlled abnormal joint movement with ACL transection (CAJM, n = 5), and control (n = 5). One week after surgery, all rats were euthanized and their knees removed. Histological analysis was performed on the knee cartilages, which involved evaluation of cell numbers and density.

Results

There were no significant differences in chondrocyte numbers among the three groups within each articular cartilage zone (surface, middle, and deep zones) nor between zones (P > 0.05). In contrast, the chondrocyte cell density area was significantly suppressed in the CAJM compared to the ACL-T group in each zone (surface zone, P = 0.019).

Conclusions

Early control of joint instability induced by ACL injury inhibited chondrocyte hypertrophy in articular cartilage. This result indicates that knee joint instability increases mechanical stress, and the controlling of these joint movements might provide a new treatment approach for the long-term prevention of osteoarthritis.

     

The effect of anterior cruciate ligament graft rotation on knee biomechanics

Purpose

The purpose of this study was to evaluate the effects on knee biomechanics of rotating the distal end of the bone-patellar tendon graft 90° in anatomic single-bundle (SB) anterior cruciate ligament (ACL) reconstruction with a porcine model.

Methods

Twenty (n = 20) porcine knees were evaluated using a robotic testing system. Two groups and three knee states were compared: (1) intact ACL, (2) deficient ACL and (3) anatomic SB ACL reconstruction with (a) non-rotated graft or (b) rotated graft (anatomic external fibre rotation). Anterior tibial translation (ATT), internal (IR) and external rotation (ER) and the in situ tissue force were measured under an 89-N anterior tibial (AT) load and 4-N m internal and external tibial torques.

Results

A significant difference from the intact ACL was found in ATT at 60° and 90° of knee flexion for rotated and non-rotated graft reconstructions (p < 0.05). There was a significant difference in the in situ force from the intact ACL with AT loading for rotated and non-rotated graft reconstructions at 60° and 90° of knee flexion (p < 0.05). Under IR loading, the in situ force was significantly different from the intact ACL at 30° and 60° of knee flexion for rotated and non-rotated graft reconstructions (p < 0.05). There were no significant differences in ATT, IR, ER and the in situ force between rotated and non-rotated reconstructions.

Conclusion

Graft rotation can be used with anatomic SB ACL reconstruction and not have a deleterious effect on knee anterior and rotational biomechanics. This study has clinical relevance in regard to the use of graft rotation to better reproduce the native ACL fibre orientation in ACL reconstruction.

     

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.

     

Evaluation of pivot shift phenomenon while awake and under anaesthesia by different manoeuvres using triaxial accelerometer

Purpose

Evaluating pivot shift phenomenon is difficult due to its subjectivity, wide variation of testing manoeuvres, and difficulty in evaluating patients while awake. The purpose of this study was to evaluate the pivot shift phenomenon using a triaxial accelerometer by two different manoeuvres, the pivot shift test as representative of flexion manoeuvre and N test as a representative of extension manoeuvre, and in two different conditions, awake and under anaesthesia.

Methods

Twenty-nine patients with unilateral anterior cruciate ligament (ACL)-injured knee were included. Pivot shift test and N test were performed for both injured and uninjured legs while awake and under anaesthesia, with the acceleration measurements using a triaxial accelerometer (KiRA). The tests were also subjectively graded on a scale of 0–6 based on the modification of IKDC criteria.

Results

Under anaesthesia, acceleration of ACL-injured knees was greater than that of uninjured knees in both pivot shift test (P < 0.001) and N test (P < 0.001), whereas the acceleration value was greater in the N test. Furthermore, there were significant positive correlations between the acceleration and subjective grading in both tests, whereas the N test was more significant than the pivot shift test. On the other hand, there was no statistical significance in acceleration between ACL-injured and uninjured knees in either test while the patient was awake.

Conclusion

The triaxial accelerometer was useful to objectively detect and quantitatively evaluate the pivot shift phenomenon by both the pivot shift test and N test under anaesthesia. The acceleration of ACL-injured knees was greater than that of uninjured knees, and the acceleration was correlated with the subjective manual grading, especially in the N test. On the other hand, its use while the patient was awake was likely limited.

Levels of evidence

Diagnostic study of non-consecutive patients without a universally applied gold standard, Level III.

     

Coronal tibial anteromedial tunnel location has minimal effect on knee biomechanics

Purpose

Studies have found anatomic variation in the coronal position of the insertion site of anteromedial (AM) bundle of the anterior cruciate ligament (ACL) on the tibia, which can lead to questions about tunnel placement during ACL reconstruction. The purpose of this study was to determine how mediolateral placement of the tibial AM graft tunnel in double-bundle ACL reconstructions affects knee biomechanics.

Methods

Two different types of double-bundle ACL reconstructions were performed. The AM tibial tunnel was placed at either the medial or lateral portion of tibial AM footprint. Nine cadaveric knees were tested with the robotic/universal force-moment sensor system with the use of (1) an 89.0-N anterior tibial load at full extension (FE), 30°, 60° and 90° of knee flexion and (2) a combined 7.0-Nm valgus torque and 5.0-Nm internal tibial rotation torque at FE, 15°, 30°and 45° of knee flexion.

Results

Both medial (2.6?±?1.2 mm) and lateral (1.6?±?0.9 mm) double-bundle reconstructions reduced the anterior tibial translation (ATT) to less than the intact value (3.9?±?0.7 mm) at FE. At all other flexion angles, there was no significant different in ATT between the intact knee and the reconstructions. At FE, the ATT for the medial AM reconstruction was different from that of the lateral AM construction and closer to the intact ACL value.

Conclusion

The coronal tibial placement of the AM tunnel had only a slight effect on knee biomechanics. In patients with differing AM bundle coronal positions, the AM tibial tunnel can be placed anatomically at the native insertion site.

     

Anatomic and non-anatomic anterior cruciate ligament posterolateral bundle augmentation affects graft function

Purpose

The purpose of this study is to compare knee laxity and graft function (tissue force) between anatomic and non-anatomic posterolateral (PL) bundle augmentation.

Methods

Twelve (n = 12) fresh-frozen mature, unpaired porcine knees were tested using a robotic testing system. Four knee states were compared: (a) intact anterior cruciate ligament (ACL), (b) deficient PL and intermediate bundles, (c) anatomic PL augmentation, and (d) non-anatomic PL augmentation. Anterior tibial translation (ATT), internal rotation (IR) and external rotation (ER), and the in situ tissue force were measured under an 89.0-N anterior tibial load and 4.0-N m internal and external tibial torques.

Results

Both anatomic and non-anatomic PL augmentation restored the ER, IR, and ATT of the intact knee at all knee flexion angles (n.s.). Both anatomic and non-anatomic PL augmentation restored the in situ tissue force of the ACL during ER and IR loading and ATT loading at all knee flexion angles except at 60° of knee flexion, where the non-anatomic PL augmentation did not restore the in situ tissue force of the ACL during external rotation loading and the anatomic PL augmentation did not restore the in situ tissue force of the ACL during IR loading. Furthermore, there were no differences in ATT, IR, ER, and in situ tissue force under anterior tibial loading, IR and ER loading between the two reconstruction groups.

Conclusion

There were no significant differences between anatomic and non-anatomic PL augmentation using the porcine knee model.

     

Anatomic double bundle ACL reconstruction outperforms any types of single bundle ACL reconstructions in controlling dynamic rotational laxity

Purpose

To compare the different types of ACL reconstructions in terms of knee dynamic laxity evaluated by acceleration.

Methods

Sixteen fresh frozen cadaveric knees were used. Pivot shift test was manually performed while monitoring the tibial acceleration by use of a triaxial accelerometer. The test was repeated before and after the ACL resection and reconstruction. Three types of ACL reconstruction were tested: (1) Anatomic Single-Bundle reconstruction (n = 8), the graft was placed at the center of the ACL footprint for the both femoral and tibial sides (tunnel diameter: 8mm); (2) Conventional Single-Bundle reconstruction (n = 8), the graft was placed from the tibial PL footprint to femoral high AM position (tunnel diameter: 8mm) and (3) Anatomic Double-Bundle reconstruction (n = 8). The acceleration in each of three x-y-z directions and the overall magnitude of acceleration was calculated to evaluate dynamic rotational laxity and compared between different ACL reconstructions.

Results

The overall magnitude of acceleration was significantly different between ACL intact and deficient knees (p < 0.0001). The acceleration was reduced by the DB ACL reconstruction to the intact level (n.s.), but the two SB ACL reconstruction failed to achieve the intact level of the acceleration (p = 0.0002non-anatomic SB, p < 0.0001 anatomic SB).

Conclusion

The anatomic DB reconstruction better restores dynamic rotational laxity when compared to the SB ACL reconstructions no matter if the tunnel placement was anatomic. The anatomic DB reconstruction better restores dynamic rotational laxity when compared to both anatomic and non-anatomic SB ACL reconstruction. For this reason anatomic DB ACL reconstruction is recommended for cases where rotational laxity is an issue.

     

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.

     

Is there a correlation between posterior tibial slope and non-contact anterior cruciate ligament injuries?

Purpose

The purpose of this study was (1) to determine differences in posterior tibial slope (PTS) between subjects who underwent ACL reconstruction following a non-contact ACL injury and a matched control uninjured group and (2) to investigate gender differences between ACL-injured subjects and gender-matched controls.

Methods

A retrospective chart review was conducted of all 316 ACL-deficient patients at a large regional academic teaching hospital. A control group was established searching the database of the same hospital for subjects who underwent knee radiographs for acute knee complaints with no ACL injury. Subjects (n = 272; males n = 199; females n = 73) were included if a non-contact mechanism could be established. Exclusion criteria included previous ipsilateral knee injury and/or knee previous surgery. PTS was measured on a digitalized lateral radiograph using the axis of the posterior tibial cortex as a reference.

Results

There was a significant difference (P = 0.008) within the ACL injury group between males and females. There was no significant difference in the PTS angle between those patients with an ACL injury (5.8 ± 3.5 degrees) and the uninjured control group (5.6 ± 3.2 degrees), or between the male ACL injury patients (5.5 ± 3.4) and their control group (5.8 ± 3.1). However, there was a significant difference between the female ACL injury patients (6.7 ± 3.7) and their uninjured control group (5.0 ± 3.4) (P = 0.004).

Conclusion

The results of this study suggest that increased posterior tibial slope appears to contribute to non-contact ACL injuries in females, but not in males.

Level of evidence

Case–control study, Level III.

     

Combined reconstruction of the anterior cruciate ligament associated with anterolateral tenodesis effectively controls the acceleration of the tibia during the pivot shift

Purpose

The pivot shift test is quantified subjectively during assessment of patients presenting with suspected Anterior Cruciate Ligament (ACL) tears and has a low interobserver reproducibility. The Kinematic Rapid Assessment (KiRA) is a triaxial accelerometer that makes it possible to non-invasively quantify tibial acceleration during the pivot shift test. Abolishing pivot shift is considered to be a key element in surgical reconstruction but is incomplete in 25–38% of patients.

Methods

Patients were included prospectively. Inclusion criteria were patients requiring ACL reconstruction associated with at least one of the following factors corresponding to the patient who have a high risk of rupture either by their sports activity, a failure case, or the notion of important rotational laxity: the patient practiced a competitive pivot-contact sport, revision ACL reconstruction (besides STG (semitendinosus-gracilis graft) repair), subjective explosive rotational laxity, Segond fracture, and TELOS value of >10 mm. Standardized pre- and postoperative pivot shift tests were immediately performed under anesthesia in both knees.

Results

Forty-three patients were included. Mean preoperative variations in tibial acceleration in the healthy and injured knees were 1.2?±?0.1 and 2.7?±?0.3 m/s², respectively, p?<?0.01. A statistically significant decrease in immediate postoperative mean variations in acceleration in the injured knee occurred: 1.5?±?0.3 m/s², p?<?0.01. There was no longer any statistical difference between postoperative contralateral healthy knees and operated knees (n.s).

Conclusions

Combined ACL reconstruction associated with anterolateral tenodesis suppress acute pathologic tibial acceleration in the pivot shift.

Level of evidence

III.

     

Contralateral knee hyperextension is associated with increased anterior tibial translation and fewer meniscal injuries in the anterior cruciate ligament-injured knee

Purpose

To investigate the influence of hyperextension of the contralateral healthy knee on anterior tibial translation (ATT) and the presence of associated injuries in the anterior cruciate ligament (ACL)-injured knee.

Methods

A local patient data register containing the surgical and clinical data of patients undergoing ACL reconstruction was analyzed. Patients were divided into groups according to the degree of hyperextension of the contralateral knee: normal (Group A ≤?0°), mild (Group B 1°–5°), moderate (Group C 6°–10°), and severe (Group D >?10°). The ATT was measured in both knees preoperatively and 6 months postoperatively using the KT-1000 arthrometer. The presence of associated meniscal and cartilage injuries was noted. Using multivariate analysis, Groups B, C, and D were compared with Group A, using this group as a reference.

Results

A total of 10,957 patients were available in the register and 8502 (Group A n?=?4335, Group B n?=?3331, Group C n?=?771, Group D n?=?65) were included in the final analysis. Groups B (10.3 mm; 95% CI 0.06–0.042, p?<?0.0001) and C (10.6 mm; 95% CI 0.23–0.89, p?=?0.006) showed significantly greater preoperative ATT in the injured knee compared with the control group (10.1 mm). Moreover, at the 6-month follow-up, greater ATT was observed for Groups B (8.5 mm; 95% CI 0.13–0.45, p?<?0.0001), C (8.5 mm; 95% CI 0.02–0.60, p?=?0.035), and D (9.1 mm; 95% CI ??0.08–1.77, p?=?0.082) compared with Group A (8.2 mm). Meniscal injuries were less frequent in patients with contralateral hyperextension [Group B 903 (27.1%) p?<?0.0001, Group C 208 (27.0%) p?=?0.0003, and Group D 12 (18.5%), 0.012] compared with the control group [Group A 1479 (34.1%)].

Conclusion

Contralateral knee hyperextension is associated with greater pre- and postoperative ATT in the ACL-injured knee. In patients with contralateral knee hyperextension, concomitant injuries to the menisci are less frequent. Surgeons should consider grafts with superior properties regarding postoperative anteroposterior laxity to patients with contralateral knee hyperextension.

Level of evidence

Retrospective cohort study, Level IV

     

Knee laxity modifications after ACL rupture and surgical intra- and extra-articular reconstructions: intra-operative measures in reconstructed and healthy knees

Purpose

Quantifying the effects of anterior cruciate ligament (ACL) deficiency on knee joint laxity is fundamental for understanding the outcomes of its reconstruction techniques. The general aim of this study was to determine intra-operatively the main modifications in knee laxity before and after standard isolated intra-articular and additional extra-articular anterolateral reinforcement. Our main hypothesis was that laxity abnormalities, particularly axial rotation, can still result from these ACL reconstruction techniques.

Methods

Thirty-two patients with primary ACL deficiency were analysed by a navigation system immediately before and after each of the two reconstructions. Laxity measurements in terms of knee translations and rotations were taken during the anteroposterior drawer test, with internal–external rotation at 20° and 90° of flexion, and varus–valgus and pivot-shift tests. All these laxity measures were also taken originally from the contralateral healthy knee.

Results

With respect to the contralateral healthy knee, in the ACL-deficient knee significantly increased laxity (expressed in %) was found in the medial compared with that of the lateral compartment, respectively, 115 and 68 % in the drawer test at 20° flexion, and 55 and 46 % at 90° flexion. In the medial compartment, a significant 35 % increment was also observed for the coupled tibial anteroposterior translation during axial knee rotation at 20° of flexion. After isolated intra-articular reconstruction, normal values of anteroposterior laxity were found restored in the pivot-shift and drawer tests in the lateral compartment, but not fully in the medial compartment. After the reinforcement, laxity in the medial compartment was also found restored in the axial rotation test at 20° flexion.

Conclusion

In ACL reconstruction, with respect to the contralateral knee, intra-articular plus additional anterolateral reinforcement procedures do not restore normal joint laxity. This combined procedure over-constrained the lateral compartment, while excessive laxity still persists at the medial one.

Level of evidence

III.

     

Native rotational knee kinematics are lost in bicruciate-retaining total knee arthroplasty when the tibial component is replaced

Purpose

To compare the kinematics between native knees and knees that have undergone bicruciate-retaining (BCR) total knee arthroplasty (TKA) with cruciate-retaining (CR) TKA converted from BCR TKA in the same whole-body cadaveric specimen using a navigation system and, if differences exist, to investigate the point at which normal kinematics are lost during the procedure.

Methods

The rotational kinematics throughout passive flexion of the native knee and of knees after meniscectomy, femoral replacement, BCR TKA, or CR TKA were assessed in nine fresh frozen cadavers using an image-free navigation system.

Results

The rotational kinematic pattern of a knee after BCR TKA was different from that of a native knee, especially in the early flexion phase, and was similar to that after CR TKA. Screw-home movement was not observed after BCR TKA, but still occurred after meniscectomy or femoral replacement with intact cruciate ligaments and an intact tibial articular surface.

Conclusion

The rotational kinematics of the native knee are not always preserved after BCR TKA. Native rotational kinematics are preserved after meniscectomy and femoral replacement, but are lost after tibial replacement in BCR TKA. Surgeons should pay close attention to maintain the anteroposterior stabilizing function of the ACL in BCR TKA, rather than to restore the native rotational kinematics.

     

Complications after epiphyseal reconstruction of the anterior cruciate ligament in prepubescent children

Purpose

Reconstruction of the anterior cruciate ligament (ACL) remains a major concern in the prepubescent, skeletally immature patient with wide open growth plates. Different surgical techniques have been proposed. This study reports the results and complications of ACL reconstruction in young children using an all epiphyseal technique.

Methods

Between 2006 and 2010, 12 patients (10–13 years, median 12.1 years) underwent epiphyseal primary ACL reconstruction, with a total of 13 knee procedures. Patients were assessed retrospectively with a median follow-up of 54 months (range 39–80 months) consisting of a clinical examination, instrumented arthrometer testing and radiological analysis. Functional status was assessed using the Lysholm knee score, Tegner activity scale and IKDC-2000 form.

Results

According to the IKDC examination form, five knees were rated as normal, six near normal and two abnormal. The median IKDC score at follow-up was 88.5 points (range 75–99 points). The mean side–to-side difference in KT-1000 ligament laxity testing was 1.5 mm (±2.5 mm). In two patients, reoperation was necessary due to graft failure. Two patients developed significant leg length inequality; one with 20 mm overgrowth and varus malalignment after re-reconstruction and the second developed arthrofibrosis and overgrowth of 16 mm. Four patients had minor limb length discrepancy ranging between +5 and +10 mm; no growth arrest was noted. One patient with an intact but slightly elongated graft required a meniscal suture 34 months after ACL reconstruction following a traumatic medial meniscal lesion.

Conclusion

Despite using the epiphyseal technique in ACL reconstruction, relevant growth discrepancy can occur. Thereby, overgrowth rates appear to potentially pose a major clinical problem, which has remained unreported so far. Overall, there is a considerable high risk of complications in this patient group.

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.