The Pivot-shift test is a clinical test for knee instability for patinets with Anterior cruciate ligament (ACL), however the test has low inter-observer reliability. Dynamic radiostereometry (dRSA) imaging is a highly precise method for objective evaluation of joint kinematics. The purpose of the study was to quantify precise knee kinematics during Pivot-shift test by use of the non-invasive dynamic RSA imaging. Eight human donor legs with hemipelvis were evaluated. Ligament lesion intervention of the ACL was performed during arthroscopy and anterolateral ligament (ALL) section was performed as a capsular incision. Pivot-shift test examination was recorded with dRSA on ligament intact knees, ACL-deficient knees and ACL+ALL-deficient knees. A Pivot-shift pattern was identifyable after ligament lesion as a change in tibial posterior drawer velocity from 7.8 mm/s in ligament intact knees, to 30.4 mm/s after ACL lesion, to 35.1 mm/s after combined ACL-ALL lesion. The anterior-posterior drawer excursion increased from 2.8 mm in ligament intact knees, to 7.2 mm after ACL lesion, to 7.6 mm after combined lesion. Furthermore a change in tibial rotation was found, with increasing external rotation at the end of the pivot-shift motion going from intact to ACL+ALL-deficient knees. This experimental study demonstrates the feasibility of RSA to objectively quantify the kinematic instability patterns of the knee during the Pivot-shift test. The dynamic parameters found through RSA displayed the kinematic changes from ACL to combined ACL-ALL ligament lesion

The Pivot-shift phenomenon (PS) is known to be one of the essential signs of functional insufficiency of the anterior cruciate ligament (ACL). To evaluate the dynamic knee laxity is very important to accurately diagnose ACL injury, to assess surgical reconstructive techniques, and to evaluate treatment approaches. However, the pivot-shift test remains a subjective clinical examination difficult to quantify. The aim of the present study is to validate the use of an innovative non-invasive device based on the use of an inertial sensor to quantify PS test. The validation was based on comparison with data acquired by a surgical navigation system. The surgeon intraoperatively performed the PS tests on 15 patients just before fixing the graft required for the ACL reconstruction. A single accelerometer and a navigation system simultaneously acquired the joint kinematics. An additional optical tracker set to the accelerometer has allowed to quantify the movement of the sensor. The tibial anteroposterior acceleration obtained with the navigation system was compared with the acceleration acquired by the accelerometer. It is therefore estimated the presence of any artifacts due to the soft tissue as the test-retest repositioning error in the positioning of the sensor. It was also examined, the repeatability of the acceleration parameters necessary for the diagnosis of a possible ACL lesion and the waveform of the output signal obtained during the test. Finally it has been evaluated the correlation between the two acceleration measurements obtained by the two sensors. The RMS (root mean square) of the error of test-retest positioning has reported a good value of 5.5 ± 2.9 mm. While the amounts related to the presence of soft tissue artifacts was equal to 4.9 ± 2.6 mm. It was also given a good intra-tester repeatability (Cronbach's alpha = 0.86). The inter-patient similarity analysis showed a high correlation in the acceleration waveform of 0.88 ± 0.14. Finally the measurements obtained between the two systems showed a good correlation (rs = 0.72, p<0.05). This study showed good reliability of the proposed scheme and a good correlation with the results of the navigation system. The proposed device is therefore to be considered a valid method for evaluating dynamic joint laxity

There have been differing descriptions of the anterolateral structures of the knee, and not all have been named or described clearly. The aim of this study was to provide a clear anatomical interpretation of these structures. We dissected 40 fresh-frozen cadaveric knees to view the relevant anatomy and identified a consistent structure in 33 knees (83%); we termed this the anterolateral ligament of the knee. This structure passes antero-distally from an attachment proximal and posterior to the lateral femoral epicondyle to the margin of the lateral tibial plateau, approximately midway between Gerdy’s tubercle and the head of the fibula. The ligament is superficial to the lateral (fibular) collateral ligament proximally, from which it is distinct, and separate from the capsule of the knee. In the eight knees in which it was measured, we observed that the ligament was isometric from 0° to 60° of flexion of the knee, then slackened when the knee flexed further to 90° and was lengthened by imposing tibial internal rotation.

Cite this article: Bone Joint J 2014;96-B:325–31.

The primary purpose of this study was to assess whether patients presenting with clinical graft laxity following primary anatomic anterior cruciate ligament (ACL) reconstruction using hamstring autograft reported a significant difference in disease-specific quality-of-life (QOL) as measured by the ACL-QOL questionnaire. Clinical ACL graft laxity was assessed in a cohort of 1134/1436 (79%) of eligible patients using the Lachman and Pivot-shift tests pre-operatively and at 12- and 24-months following ACL reconstruction. Post-operative ACL laxity was assessed by an orthopaedic surgeon and a physical therapist who were blinded to each other's examination. If there was a discrepancy between the clinical examination findings from these two assessors, then a third impartial examiner assessed the patient to ensure a grading consensus was reached. Patients completed the ACL-QOL questionnaire pre-operatively, and 12- and 24-months post-operatively. Descriptive statistics were used to assess patient demographics, rate of post-operative ACL graft laxity, surgical failures, and ACL-QOL scores. A Spearman rho correlation coefficient was utilised to assess the relationships between ACL-QOL scores and the Lachman and Pivot-shift tests at 24-months post-operative. An independent t-test was used to determine if there were differences in the ACL-QOL scores of subjects who sustained a graft failure compared to the intact graft group. ACL-QOL scores and post-operative laxity were assessed using a one-way analysis of variance (ANOVA). There were 70 graft failures (6.17%) in the 1134 patients assessed at 24-months. A total of 226 patients (19.9%) demonstrated 24-months post-operative ACL graft laxity. An isolated positive Lachman test was assessed in 146 patients (12.9%), an isolated positive Pivot-shift test was apparent in 14 patients (1.2%), and combined positive Lachman and Pivot-shift tests were assessed in 66 patients (5.8%) at 24-months post-operative. There was a statistically significant relationship between 24-month post-operative graft laxity and ACL-QOL scores (p < 0.001). Specifically, there was a significant correlation between the ACL-QOL and the Lachman test (rho = −0.20, p < 0.001) as well as the Pivot-shift test (rho = −0.22, p < 0.001). There was no significant difference between the scores collected from the graft failure group prior to failure occurring (mean = 74.38, SD = 18.61), and the intact graft group (mean = 73.97, SD = 21.51). At 24-months post-operative, the one-way ANOVA demonstrated a statistically significant difference between the ACL-QOL scores of the no laxity group (mean = 79.1, SD = 16.9) and the combined positive Lachman and Pivot-shift group (mean = 68.5, SD = 22.9), (p = 0, mean difference = 10.6). Two-years post ACL reconstruction, 19.9% of patients presented with clinical graft laxity. Post-operative graft laxity was significantly correlated with lower ACL-QOL scores. The difference in ACL-QOL scores for patients with an isolated positive Lachman or Pivot-shift test did not meet the threshold of a clinically meaningful difference. Patients with clinical laxity on both the Lachman and Pivot-shift tests demonstrated the lowest patient-reported ACL-QOL scores, and these results exceeded the minimal clinically important difference

A total of 218 patients with unilateral anterior cruciate ligament deficiency were randomly assigned to one of four groups. In group A an anatomical double bundle anterior cruciate ligament reconstruction was performed; group B were treated by a single bundle using an Endobutton for femoral fixation; in group C by a single bundle using RigidFix cross pins for femoral fixation; and in group D by a single bundle using a bioabsorbable TransFix II screw for femoral fixation. For tibial fixation a bioabsorbable Intrafix interference screw was used for all the groups and the graft was fashioned from the semitendinosus and gracilis tendons in all patients. In all, 18 patients were lost to follow-up. The remaining 200 were subjected to a clinical evaluation, with assessment of the anterior drawer, Lachman’s and the pivot-shift tests, and KT-1000 arthrometer measurement. They also completed the International Knee Documentation Committee, Lysholm knee and Tegner activity scores. At a mean of 29 months (25 to 38) follow-up there were no significant differences concerning time between injury and range of movement and Lysholm knee scores among the four groups. However, the double bundle method showed significantly better results for the pivot-shift test (p = 0.002). The KT 1000 measurements showed a mean difference between the reconstructed knee and the patients’ normal knee of 1.4 mm in the double bundle group and 2.4 mm in the single bundle group; which was statistically significant. The Lachman and anterior drawer tests also showed superior results for the double bundle method. The International Knee Documentation Committee scale showed no significant difference among the groups (p < 0.001). On clinical evaluation the double bundle group showed less laxity than the single bundle groups. However, regardless of the technique, all knees were improved by anterior cruciate ligament reconstruction compared with their pre-operative status

Patellar dislocation is a common presentation with a clear management pathway. Sometimes, however, what a patient experiences as the patella dislocating may, in fact, be ACL insufficiency. We reviewed case notes and imaging of 315 consecutive ACL reconstructions, collecting data on the date and mechanism of injury, time to MRI, and reconstruction. We noted cases initially diagnosed as patellar dislocation. 25 of 315 (7.9%) patients were initially diagnosed with a patellar dislocation. Subsequently, however, MRI scans revealed no evidence of patellar dislocation and instead showed ACL rupture with pathognomonic pivot-shift bony oedema. The false patella dislocation group were 32% female and had an average age of 25; the rest of the group average age was 27.1 and there were a lower proportion of females; 21%. The false patella instability patients had a median waiting time of 412 days from injury to operation (range: 70-2445 days), compared to 392 days (range: 9 – 4212 days) for rest of the patients. 5 of the remaining 290 had MRIs showing patella oedema with medial patello-femoral ligament injury in addition to their ACL rupture. From our literature search this is a new finding which shows that ACL rupture can present with symptoms suggestive of patellar dislocation. These findings raise the risk that there are a group of people who have been diagnosed with patellar instability who instead have ACL insufficiency and so are at risk of meniscal and chondral damage. Further research should analyse those diagnosed with patellar instability to quantify missed ACL injuries

The aim of an anterior cruciate ligament (ACL) reconstruction is to regain functional stability of the knee following ACL injury, ideally allowing patients to return to their pre-injury level of activity. The purpose of this study was to assess clinical, functional and patient-centered outcomes a minimum of 1-year following ACL reconstruction. This study assessed for relationships between post-operative ACL graft laxity, functional testing performance, and scores on the ACL Quality of Life (ACL-QOL) questionnaire. A prospective cohort study design (n = 1938) was used to gather data on clinical laxity, functional performance and quality of life outcomes. Post-operative ACL laxity assessment using the Lachman and Pivot-shift tests was completed independently on each patient by a physiotherapist and an orthopaedic surgeon at a minimum of 12-months post-operatively. A battery of functional tests was performed including single leg balance, single leg landing, 4 single-leg hop tests, and tuck jumps. The hop tests provided a comparative assessment of limb-to-limb function including a single hop for distance, a 6m timed hop, a triple hop for distance, and a triple crossover hop. Patients com¬pleted the ACL-QOL at the 12-month and 24-month post-operative appointments. Descriptive and demographic data were collected for all patients. The degree and frequency of post-operative laxity was calculated. A Pearson r correlation coefficient was employed to determine the relationship between the presence of post-operative laxity and the ACL-QOL scores, between the battery of functional tests and the ACL-QOL scores, as well as between the functional tests and the laxity assessments. Data was gathered for 1512/1938 patients (78%). At clinical assessment a minimum of 1-year post-operatively, 13.2% of patients demonstrated a positive Lachman and/or Pivot-shift test. The mean ACL-QOL score for patients with no ACL laxity was 80.8/100, for patients with a positive Lachman or Pivot-shift test the mean score was 72.3/100, and for patients with both positive Lachman and Pivot-shift tests the score was 66.9/100. Pearson r correlation coefficient demonstrated a significant relationship between the presence of ACL graft laxity and ACL-QOL score (p < 0.05). Statistically significant correlations were evident between all of the operative limb single-leg hop tests and the post-operative ACL-QOL scores (p < 0.05). Statistically significant correlations were evident between the operative limb triple-hop tests and presence of ACL graft laxity (p < 0.05). Patients with clinically measurable ACL graft laxity demonstrate lower ACL-QOL scores as well as lower performance on a battery of functional tests. The disease-specific outcome measure was strongly correlated to the patient's ability to perform single-limb functional tests, indicating that the ACL-QOL score accurately predicted level of function

The aim of an anterior cruciate ligament (ACL) reconstruction is to regain functional stability of the knee following ACL injury, ideally allowing patients to return to their pre-injury level of activity. The purpose of this study was to assess clinical, functional and patient-reported outcomes following primary ACL reconstruction with hamstring autograft. A prospective case-series design (n=1610) was used to gather data on post-operative ACL graft laxity, functional testing performance and scores on the ACL quality of life (ACL-QOL) questionnaire. Demographic data were collected for all patients. Post-operative ACL laxity assessment using the Lachman and Pivot-shift tests was completed independently on each patient by a physiotherapist and an orthopaedic surgeon at the 6-, 12- and 24-months post-operative appointments. A battery of functional tests was also assessed including single leg Bosu balance, and 4 single-leg hop tests. The hop tests provided a comparative assessment of limb-to-limb function. Patients completed the ACL-QOL at all time points. The degree and frequency of post-operative laxity was calculated. A Spearman's rank correlation matrix was undertaken to assess for relationships between post-operative laxity, functional test performance, and the ACL-QOL scores. A linear regression model was used to assess for relationships between the ACL-QOL scores, as well as the functional testing results, and patient demographic factors. ACLR patients were 55% male, with a mean age of 29.7 years (SD=10.4), mean BMI of 25 (SD=3.9), and mean Beighton score of 3.3 (SD=2.5). At clinical assessment 2-years post-operatively, 20.6% of patients demonstrated a positive Lachman test and 7.7% of patients demonstrated a positive Pivot-shift test. The mean ACL-QOL score was 28.6/100 (SD=13.4) pre-operatively, 58.2/100 (SD=17.6) at 6-months, 71.8/100 (SD=18.1) at 12-months, and 77.4/100 (SD=19.2) at 24-months post-operative. Functional tests assessing operative to non-operative limb performance demonstrated that patients were continuing to improve up to the 24-month mark, with limb symmetry indices ranging from 96.6–103.1 for the single-leg hop tests. Spearman's correlation coefficient demonstrated a significant relationship between the presence of ACL graft laxity and ACL-QOL score at 12- and 24-months post-operative (p < 0 .05). Functional performance on the single leg balance and single-leg hop tests demonstrated significant correlations to the 6-, 12- and 24-month ACL-QOL scores (p < 0 .05). There was no statistically significant correlation between the functional testing results and the presence of ACL graft laxity. This study demonstrated that up to 20.6% of patients had clinically measurable graft laxity 2-years after ACLR. In this cohort, patients with graft laxity demonstrated lower ACL-QOL scores, but did not demonstrate lower functional testing performance. Patient-reported ACL-QOL scores improved significantly at each time point following ACLR, and functional performance continued to improve up to 2-years after surgery. The ACL-QOL score was strongly correlated to the patient's ability to perform single-limb functional tests, indicating that the ACL-QOL score accurately predicted level of function

We report the clinical outcome and findings at second-look arthroscopy of 216 patients (mean age 25 years (11 to 58)) who underwent anterior cruciate ligament (ACL) reconstruction or augmentation. There were 73 single-bundle ACL augmentations (44 female, 29 male), 82 double-bundle ACL reconstructions (35 female, 47 male), and 61 single-bundle ACL reconstructions (34 female, 27 male). In 94 of the 216 patients, proprioceptive function of the knee was evaluated before and 12 months after surgery using the threshold to detect passive motion test. Second-look arthroscopy showed significantly better synovial coverage of the graft in the augmentation group (good: 60 (82%), fair: 10 (14%), poor: 3 (4%)) than in the other groups (p = 0.039). The mean side-to-side difference measured with a KT-2000 arthrometer was 0.4 mm (-3.3 to 2.9) in the augmentation group, 0.9 mm (-3.2 to 3.5) in the double-bundle group, and 1.3 mm (-2.7 to 3.9) in the single-bundle group: the result differed significantly between the augmentation and single-bundle groups (p = 0 .013). No significant difference in the Lysholm score or pivot-shift test was seen between the three groups (p = 0.09 and 0.65, respectively). In patients with good synovial coverage, three of the four measurements used revealed significant improvement in proprioceptive function (p = 0.177, 0.020, 0.034, and 0.026). We conclude that ACL augmentation is a reasonable treatment option for patients with favourable ACL remnants. Cite this article: Bone Joint J 2014;96-B:1325–32

Introduction: The anterior cruciate ligament (ACL) can be anatomically divided into two bundles: the anteromedial (AM) and the posterolateral (PL). These two bundles have unique contributions to load transfer across the knee joint. Material and Methods: We retrospectively reviewed the clinical results of a consecutive series of 25 patients who underwent partial ACL reconstruction. In 22 cases AM bundle reconstruction was performed, and in 3 patients isolated PL bundle reconstruction was performed. The 25 patients included 7 women and 18 men with an average age of 29.2 years at the time of surgery. Preoperative evaluation was conducted using manual Lachman test, pivot-shift tests, KT-1000, magnetic resonance imaging and passive stress radiographs of both knees. In all cases preoperative clinical evaluation was graded C as per the IKDC scoring system. The preoperative side-to-side anterior laxity measured by means of the KT-1000 was 5.8 mm in case of AM bundle rupture and 4.3 mm in case of PL bundle rupture. All the patients underwent single-bundle reconstruction of the ACL under arthroscopic assistance (one single incision technique). In case of AM bundle repair, the type of graft used was all autologous and included bone-patellar tendon-bone in 14 cases, 4-strand hamstring tendons in 5 cases and 2-strand hamstring tendons in 3 cases. In case of PL bundle repair, 2-strand hamstring tendons transplant was used in the 3 cases. Results: In all cases, postoperative clinical evaluation was graded A as per the IKDC knee examination scoring system. No abnormal sagittal laxity was found with the Lachman manual test. Postoperative IKDC knee subjective evaluation score averaged 81.3 % [58–95] at an average of 9 months follow-up. Postoperative side-to-side anterior laxity measured with KT-1000 averaged 0.46 mm in case of AM bundle rupture and 0.5 mm in case of PL bundle rupture. Postoperatively, all the patients had full extension of the knee. The flexion was the same as contra lateral knee in 92 % of the cases. We had no postoperative complication. Discussion: Diagnosis of partial ACL rupture is often difficult. If the AM bundle is torn, the Lachman manual test is soft and the pivot-shift test is more often equal or glide. If the Lachman manual test is intermediary between firm and soft and the pivot-shift test is clunk, PL rupture has probably occurred. The size of the graft was smaller than in one bundle procedures and was matched with the size of the bundle reconstucted. Peroperative technical difficulties were to preserve the healthy bundle and to drill the femoral tunnel in case of posterolateral bundle reconstruction. Conclusion: This study showed consistent postoperative results. If partial rupture of the ACL can be diagnosed, isolated AM or PL bundle reconstruction should be considered

We identified a series of 128 patients who had unilateral open reconstruction of the anterior cruciate ligament (ACL) by a single surgeon between 1993 and 2000. In all, 79 patients were reviewed clinically and radiologically eight to 15 years after surgery. Assessment included measurement of the Lysholm and Tegner scores, the ACL quality-of-life score and the Short Form-12 score, as well as the International Knee Documentation Committee clinical assessment, measurement of laxity by the KT-1000 arthrometer, a single-leg hop test and standardised radiography of both knees using the uninjured knee as a control. Of the injured knees, 46 (57%) had definite radiological evidence of osteoarthritis (Kellgren-Lawrence grade 2 or 3), with a mean difference between the injured and non-injured knees of 1.2 grades. The median ACL quality-of-life score was 80 (interquartile range (IQR) 60 to 90), the Lysholm score 84 (IQR 74 to 95), the Short Form-12 physical component score 54 (IQR 49 to 56) and the mean Hop Index 0.94 (0.52 to 1.52). In total 58 patients were graded as normal, 20 as nearly normal and one as abnormal on the KT-1000 assessment and pivot-shift testing. Taking the worst-case scenario of assuming all non-attenders (n = 48), two septic failures and one identified unstable knee found at review to be failures, the failure rate was 40%. Only two of the patients reviewed stated that they would not have similar surgery again. Open reconstruction of the ACL gives good, durable functional results, but with a high rate of radiologically evident osteoarthritis

To compare the early functional and clinical results, between single (SB) and double-bundle (DB) of Anterior Cruciate Ligament (ACL) reconstruction with hamstrings (HS). Thirty-six patients from 17 to 36 years old (average age 23), 22 ♂ and 14 ♀, from January 2006 to May 2008, were randomly allocated for ACL reconstruction with HS (SB – DB). Eighteen patients underwent a 4-stranded SB reconstruction (group A) and the remaining 18 underwent an anatomic, 2-stranded DB ACL reconstruction with 2 tibial and 2 femoral tunnel technique (group B), by using the Smith & Nephew instrumentation system. The follow-up was from 8 to 22 months (average 16 months) for both groups and included clinical evaluation (pivot-shift test, anterior laxity test with KT-1000 arthrometer and Lysholm knee score) and radiographs. There were no statistically significant difference in the results between the 2 groups with regard to the pivot-shift test and the Lysholm score (SB: mean 91, DB: mean 89) (Mann-Whitney test, T-test). The anterior laxity was not significantly different between group A (mean, 2.2mm) and group B (mean, 0.9mm), according to KT-1000 measurements. Rotational stability, as evaluated by pivot-shift test, was better in group B than in group A, but statistical analysis showed no significant difference. The average operation time was longer in DB (110 min) compared to SB (80 min). There were no infections, though one patient of each group was found to be complicated with fixed flexion and extension lag > 5°; and underwent arthroscopic lysis. Our study shows no statistically significant advantage of DB versus SB ACL reconstruction, concerning the clinical evaluations and the complications

Previous studies have identified the anterolateral complex (ALC) as having an important role in controlling anterolateral rotatory laxity following anterior cruciate ligament injury and subsequent reconstruction. In particular, injury to the iliotibial band (ITB) and its component deep (dITB) and capsulo-osseous (coITB) layers, have been shown to significantly correlate with different grades of the pivot-shift test in patients with acute ACL injuries. However, the kinematic properties of the capsulo-osseous layer of the ITB, throughout knee range of motion, are not fully understood. The purpose of this study was to quantify the kinematic behaviour of the capsulo-osseous layer of the ITB through various degrees of knee flexion. Ten fresh-frozen cadaveric knee specimens were dissected to expose the capsulo-osseous layer of the iliotibial band. Radiopaque beads were embedded, at standardized increments (12.5%, 25%, 50% and 75% of total length from proximal to distal), into the tissue and fluoroscopic images were taken from 0o to 105o of knee flexion in 15° increments. The positions of the beads were identified in each image and the length, width, and area changes of the capsulo-osseous layer were calculated. Comparisons of the total length of the anterior and posterior borders of the coITB through knee ROM were conducted using a two-way (8 knee angles by 2 borders) repeated measures analysis of variance (rm-ANOVA), whereas the effect of knee angle on isometry and total area changes was assessed using one-way rm-ANOVAs (α=0.05). There was a significant increase in the length of the anterior capsulo-osseous layer at flexion angles greater than 15o and on the posterior border at angles greater than 75 o with changes occurring primarily at 12.5 % of the total length. In addition, at all flexion angles the length changes were significantly larger in the anterior border compared to the posterior border. Meanwhile, non-homogenous decreases in width and area were found with increasing flexion angle. The distance between the capsulo-osseous layer insertion on the distal femur and proximal tibia significantly increased from 60o-105o, maximal changes occurred at 105o (9.64 [4.12] %, p = 0.003). The primary finding of this study was that the coITB behaved in a non-isometric fashion, with significant increases in length occurring at flexion angles greater than 15o. Moreover, these changes in length were non-homogenous across the different regions of the coITB that were investigated, with the greatest changes occurring in the proximal segments (0–25%). The data presented here suggest that coITB in flexion angles from 0o to 105o behaves in a non-isometric fashion, with the majority of its length change occurring in its proximal segment. Further quantification of the pathway that the coITB takes with respect to osseous landmarks may result in improvements in ALC procedures as an augmentation to ACL reconstruction, thereby potentially improving rotational stability and clinical outcomes

The purpose of this study was to establish the return of function to an unstable knee following stabilization of the anterior deficient cruciate ligament. 15 consecutive cases of chronic anterior cruciate ligament rupture with instability were studied prior to stabilization by patellar bone-tendon-bone autograph, and again at three months post-operation and at one year post stabilization. There were two women and thirteen men in this study. All operations were performed by one of the authors (John Fleetcroft). Peak torque, total work and average power were studied at 90°/sec and 120°/sec. Three patients had unusually low contralateral flexor power at 120°/sec pre-operatively, these measurements were excluded from the 120°/sec results. Our findings show an initial decrease of strength three months postoperatively; on the extensors more than on the flexors.The flexors recovered faster than the extensors. Extensor function showed a deficit of 13% at both speeds pre-operatively. Three months following surgery this has increased to an average of 33.7% at 90°/sec and 22.8% at 120°/sec. At one year the deficit had decreased dramatically to 2.2% at 90°/sec and 0.14% at 120°/sec. Flexor function at 90°/sec showed a deficit of 6.4% pre-operatively, 15% at three months and 1.7% at one year. At 120°/sec, pre-operative flexor deficit was 3.1%, +0.16% at three months and +4.4% at one year. These tests demonstrate the return of function to unstable cruciate deficient knees, an important observation for those wishing to return to sport. Defects of the anterior cruciate ligament have been treated surgically with intra- and extra-articular procedures since several decades, either as direct repair or using autografts of the hamstring or patella tendon in open or arthroscopic operations. On the other hand there are studies about successful results of conservative treatment available, too. Casteleyn et al (1) reported about the follow up of at least five years (mean 8.5 years) of 109 patients which excluded professional and high level athletes. The evaluation of their symptoms with an IKDC score showed 23% in grade A and 50% in grade B out of four possible grades with an incidence of 5.4% secondary ACL surgery. In an editorial article about anterior cruciate ligament reconstruction Dandy et al (2) reviewed the results of several studies about intra- and extra-articular procedures, which examined pivot-shift and restriction of activity. Johnson et al (3) found in 87 patients with bone-patellar tendon-bone reconstruction and a mean follow up of 7.9 years 26% positive pivot shift and 25% of the patients had unrestricted activity. Sandberg et al (4) reviewed a similar group of 89 patients after seven years with 11% positive pivot-shift and 24% unrestricted activity. In comparison to these results extra-articular procedures show a higher incidence of pivot-shift and lower levels of unrestricted activity; Odensten et al (5) report 59% clinical instability four years after Ellison procedure and 39% positive pivot-shift with only 44% unrestricted sport activity at six years after MacIntosh operation. Over the last years extra-articular procedures were abandoned in favor for intra-articular operations. Today bone-patellar tendon-bone grafts are widely used for these repairs. Clancy et al (6) and Butler et al (7) have shown in animal studies a decrease of strength and mechanical properties postoperatively during an initial period of revascularisation and remodelling. Grontvedt et al (8) look at these properties in their study about the effects of the use of a ligament augmentation device by isokinetic testing on a Biodex™ system. They measured peak torque and total work and found a deficit in the quadriceps strength in comparison to the uninjured knee of 25% at six months, 15% at one year and 10% at two years. The hamstrings improved to equal levels already after six months. The aim of our study was to assess the mechanical properties torque, total work and average power of the hamstrings and quadriceps in order to evaluate the progress of the patients postoperatively including the above mentioned initial decrease in strength. The testing was performed with a Cybex™ machine preoperatively as well as three and twelve months postoperatively. We tested patients who had a bone-tendon-bone anterior cruciate ligament reconstruction performed between March 1998 and January 1999. It was only a limited time window available for this study and therefore we could conduct the tests only on 15 consecutive patients. We tested two women and 13 men. Their mean age was 38.4 years (21 to 50). Injuries of the anterior cruciate ligament were confirmed by both clinical and arthroscopic examination. Indications were clinical instability, pain and / or swelling during sport or other physical activity and / or other relevant history (knee gives way). All the operations were arthroscopic assisted procedures. They were performed by only one surgeon (J P Fleetcroft). The graft was obtained from the middle third of the patellar tendon and fixed with Acufex™ interference screws. The isokinetic tests were performed preoperatively, then three months postoperatively and one year postoperatively. The following parameter were obtained for both flexors and extensors at two speeds (90°/sec and 120°/sec): peak torque, total work and average power. At the preoperative test both injured and contralateral knees were tested, at three months and one year only the involved knee. The figures of the uninvolved knee were used as references to calculate mean deficit / progress percentages for the operated side during the course of the study. Three patients (number 2, 6 and 14) showed at the preoperative measurements unusually low strength at the 120°/sec tests of the flexors of their uninjured knees. The figures of the uninjured knees had to be used as references in the evaluation of progress / deficits of the injured and operated knees. Therefore all calculated results of those three patients became unrealistically high and did not represent true values. As the mechanical properties of the uninjured knees were otherwise of no interest for this study we decided to exclude these patients from the 120°/sec flexor tests. Preoperatively the extensors showed a deficit of strength (average of peak torque, total work and average power) at both speeds of 13%. This deficit worsened at three months to 33.7% at 90°/sec and 22.8% at 120°/sec. After one year strength had improved nearly to the preoperative level with a deficit of 2.2% at 90°/sec and 0.14% at 120°/sec. Flexors: The flexors showed smaller deficits than the extensors. Preoperative figures show deficits of 6.4% at 90°/sec and 3.1% at 120°/sec. At three months the deficit at 90°/sec worsened to 15% but at 120°/sec it improved to the level of the unoperated leg (+0.16%). After one year the strength was at both speeds better than at the unoperated leg (+1.7% at 90°/sec and +4.4% at 120°/sec). The detailed deficit / progress figures for all the measured properties of our study are shown in the tables below. Table 1 Mean deficit / progress [%]; PT = peak torque, TW = total work, Pow = average power. Table 2 Deficit / progress [%] of strength (average of peak torque, total work, average power). The strength deficits which resulted from the anterior cruciate ligament defect improved significantly. In both muscle groups and at both test speeds the average strength of the operated knee was after 12 months at about the same level as the uninjured leg. As the flexors are to a lesser extent effected by the operation than the extensors they recovered faster; similar to the findings of Grontvedt et al (8). The flexors showed at both speeds slightly better results than the uninvolved knee and only the extensors had still a small deficit of 0.147% (120°/sec) and 2.21% (90°/sec) in comparison to the uninjured knee after 12 months. Further could be shown that apart from flexors at 120°/sec an initial decrease in strength occurred at the three months measurements (as also reported in [6] and [7]). Grontvedt et al ( 8) still report about 25% weakness of the extensors after six months. In our study already at three months all groups apart from the extensors at 90°/sec (−33.7%) have results better than this (−22.8%, −15.04%, +0.17%). Grontvedt’s study shows 15% deficit after one year and 10% after two years. In comparison to this we could demonstrate nearly normal results (−2.2%, −0.14%, +1.7%, +4.4%) after 12 months. As the test speed influences the results especially during the initial period of decreased strength and Grontvedts study tested at 60 and 240°/sec this might be one reason for the different results. The overall figures for the patients’ progress are satisfactory. They demonstrate the return of function to an initially unstable cruciate deficient knee. We would suggest further research into the details of the initial weakness during the first postoperative months as this might have implications for physiotherapy and rehabilitation as well as surgical technique and devices

Purpose of the study: Reconstruction of the anterior cruciate ligament (ACL) has become a common procedure. We compared two randomized series: intra-articular (Kenneth-Jones) versus intra- and extra-articular (MacInJones). Material and methods: From January 1995 through March 1998, 73 knees were treated surgically for differential medial laxity measured at 7 to 12 mm on passive stress x-rays in 20° flexion. Group 1 (ACL reconstruction alone) included 34 patients (aged 27.1±7.5 years). Group 2 (ACL reconstruction plus extra-articular plasty) included 29 patients (aged 28.5±12 years). Function was scored 72% in group 1 and 68% in group 2 at mean seven years follow-up (102 and 93 months follow-up respectively). Anterior laxity was measured radiographically and with KT-1000 and the position of the tunnels was assessed according to Aglietti. Results: According to the IKDC, functional outcome was 83.9±3.1 in group 1 and 83.3±3.6 in group 2. The overall IKDC classification was 0A, 57.8% B, 26.3% C, and 15.7% D for group 1 and 58% A, 52.9% B, 29.4% C, and 11.7% D for group 2. The pivot-shift test was negative in 61.1% of group 1 knees (27.7% grade 1 and 11.1% grade 2) and negative in 83.3% of group 2 knees (16.6% grade 1). In group 1, the radiological drawer showed 46.09% improvement in the differential laxity for the medial compartment and 41% for lateral compartment. In group 2 the corresponding improvements were 44.8% and 44.6%. There was no difference in tunnel position between the two groups. Discussion: The two-year results of this series did not provide any evidence favoring a clear advantage of complementary lateral plasty. At seven years follow-up, the pivot-shift test appeared to favor associated lateral plasty (p=0.09), but with no significant difference in laxity for the two compartments. Conclusion: Anterior laxity was only incompletely controlled by both reconstruction techniques. In this context of relatively limited laxity (7–12 mm initially), at seven years follow-up there was no certain advantage of complementary lateral extra-articular plasty in combination with ACL reconstruction

Joint laxity assessments have been a valuable resource in order to understand the biomechanics and pathologies of the knee. Clinical laxity tests like the Lachman test, Pivot-shift test and Drawer test are, however, subjective of nature and will often only provide basic information of the joint. Stress radiography is another option for assessing knee laxity; however, this method is also limited in terms of quantifiability and one-dimensionality. This study proposes a novel non-invasive low-dose radiation method to accurately measure knee joint laxity in 3D. A method that combines a force controlled parallel manipulator device, a medical image and a biplanar x-ray system. As proof-of-concept, a cadaveric knee was CT scanned and subsequently mounted at 30 degrees of flexion in the device and placed inside a biplanar x-ray scanner. Biplanar x-rays were obtained for eleven static load cases. The preliminary results from this study display that the device is capable of measuring primary knee laxity kinematics similar to what have been reported in previous studies. Additionally, the results also display that the method is capable of capturing coupled motions like internal/external rotation when anteroposterior loads are applied. We have displayed that the presented method is capable of obtaining knee joint laxity in 3D. The method is combining concepts from robotic arthrometry and stress radiography into one unified solution that potentially enables unprecedented 3D joint laxity measurements non-invasively. The method potentially eliminates limitations present in previous methods and significantly reduces the radiation exposure of the patient compared to conventional stress radiography

We describe 129 patients with disabling instability of the knee due to deficiency of the anterior cruciate ligament. They were treated by replacement of the ligament with a Leeds-Keio prosthesis supplemented by an extra-articular MacIntosh lateral substitution reconstruction. After an average period of 71 months a satisfactory outcome was found in only 60% of knees. Nine had required revision because of recurrent instability and the pivot-shift sign had become positive in 40% of patients. In our opinion the long-term results are unsatisfactory when compared with those obtained using a graft from the medial third of the patellar tendon supplemented with a MacIntosh extra-articular tenodesis

A new method of demonstrating sagittal laxity in the anterior cruciate-deficient knee is described. Seventy such knees were compared to 70 normal knees. Sagittal laxity was recorded as the average displacement of the medial and lateral femoral condyles. This displacement index was significantly different between the two groups of knees (P less than 0.0001). A range for normal and abnormal knees is discussed. Quantitative assessment of the degree of sagittal laxity by clinical evaluation is shown to be unreliable. Only the pivot-shift test demonstrated any significant correlation with the amount of sagittal displacement (P less than 0.05)

Sixty-five knees were subjected to a kinematic analysis using the instant-centre technique in order to determine the effect of deficiency of the anterior cruciate ligament on the biomechanics of active movement in the knee. The instant-centre pathway in acute ruptures of the anterior cruciate ligament was found to have a specific abnormality. This corresponded with a positive pivot-shift sign, but was present even when that sign was not clinically detectable. Primary repair using a transosseous wire suture did not usually abolish the biomechanical abnormality. The data provide a possible explanation for the doubtful prognosis of primary repair of this ligament and encourage clinical and biomechanical evaluation of alternative procedures such as primary augmented repair

Our objectives were to establish the envelope of passive movement and to demonstrate the kinematic behaviour of the knee during standard clinical tests before and after reconstruction of the anterior cruciate ligament (ACL). An electromagnetic device was used to measure movement of the joint during surgery. Reconstruction of the ACL significantly reduced the overall envelope of tibial rotation (10° to 90° flexion), moved this envelope into external rotation from 0° to 20° flexion, and reduced the anterior position of the tibial plateau (5° to 30° flexion) (p < 0.05 for all). During the pivot-shift test in early flexion there was progressive anterior tibial subluxation with internal rotation. These subluxations reversed suddenly around a mean position of 36 ± 9° of flexion of the knee and consisted of an external tibial rotation of 13 ± 8° combined with a posterior tibial translation of 12 ± 8 mm. This abnormal movement was abolished after reconstruction of the ACL