Uninjured Knee Research Articles

Large post-traumatic bone marrow lesions after ACL injury are not associated with knee pain and symptoms within 4 weeks of injury

s / Osteoarthritis and Cartilage 22 (2014) S57–S489 S178 may enable clinicians to provide targeted rehabilitation programs which could improve outcomes in people with hip chondropathy. 301 LARGE POST-TRAUMATIC BONE MARROW LESIONS AFTER ACL INJURY ARE NOT ASSOCIATED WITH KNEE PAIN AND SYMPTOMS WITHIN 4 WEEKS OF INJURY J.B. Driban y, L.S. Lohmander z, R. Frobell z. y Tufts Med. Ctr., Boston, MA, USA; zOrthopedics, Clinical Sci. Lund, Lund Univ., Lund, Sweden Purpose: Following an anterior cruciate ligament (ACL) tear most knees have a bone marrow lesion (BML); however, the clinical relevance of these post-traumatic lesions remains unclear. Previous studies have suggested that post-traumatic BMLs are associated with pain. We explored the cross-sectional associations between post-traumatic BML volume and self-reported knee pain and symptoms in individuals with acute ACL injury where almost everyone suffered from at least one posttraumatic BML. Our primary focus was the total BML volume of the injured knee, secondary focus was on the tibiofemoral compartments, and the separate condyles were exploratory. Methods: 121 young active adults (mean age 26 [SD 4.9] years) with an acute ACL tear to a previously uninjured knee were studied as part of a randomized clinical trial (The KANON-trial). BML volume was automatically segmented from 1.5 Tesla magnetic resonance (MR) images, obtained within 4 weeks of injury, using a composite dataset made up of a sagittal dual-echo turbo-spin echo and sagittal short tau inversion recovery sequences (Virtualscopics Inc., Rochester (NY), USA). Selfreported pain and symptoms of the injured knee was obtained at the same day as MR imaging using the KOOS questionnaire (0-100, worst to best). A depression fracture as visualized on MR imaging was shown to have a strong relation to BML volume but could influence pain through other mechanisms; thus we stratified our primary analysis for those with and without a depression fracture. We used multiple linear regression models to assess the cross-sectional association between KOOS pain or symptoms (outcome variables) and total knee BML volume (primary aim), medial and lateral tibiofemoral BML volume (secondary aims), and regional BML volumes (exploratory aims) collected within 4 weeks of injury. We present crude results and results adjusted for time from injury to MR imaging, age, body mass index, and sex. Results: The majority of participants were male (74%), had at least one BML in the knee (96%), and had a depression fracture in the knee (57%). The participants reported both knee pain (mean 57 [SD 17]) and knee symptoms (48 [17]) at the same day as MR imaging acquisition but total knee BML volume was not related to self-reported knee pain for the entire cohort (p 1⁄4 0.25, Table 1). Among those without a depression fracture, larger total knee BML volume was associated with increased knee pain scores (p1⁄4 0.02); however, no associationwas found for those with a depression fracture (p 1⁄4 0.96). Larger medial (p 1⁄4 0.02), but not lateral (p 1⁄4 0.77), tibiofemoral BML volume was associated with increased pain scores, specifically when BMLswere present in themedial femoral condyle (p 1⁄4 0.05, Table 1). We found no association between

Editor's Spotlight/Take 5: Mesenchymal Stem Cells in Synovial Fluid Increase After Meniscus Injury

Editor's Spotlight/Take 5: Mesenchymal Stem Cells in Synovial Fluid Increase After Meniscus Injury

Increased Slope of the Lateral Tibial Plateau Subchondral Bone Is Associated With Greater Risk of Noncontact ACL Injury in Females but Not in Males

Background: There is an emerging consensus that increased posterior-inferior directed slope of the subchondral bone portion of the tibial plateau is associated with increased risk of suffering an anterior cruciate ligament (ACL) injury; however, most of what is known about this relationship has come from unmatched case-control studies. These observations need to be confirmed in more rigorously designed investigations. Hypothesis: Increased posterior-inferior directed slope of the medial and lateral tibial plateaus are associated with increased risk of suffering a noncontact ACL injury. Study Design: Case-control study; Level of evidence, 3. Methods: In sum, 176 athletes competing in organized sports at the college and high school levels participated in the study: 88 suffering their first noncontact ACL injury and 88 matched controls. Magnetic resonance images were acquired, and geometry of the subchondral bone portion of the tibial plateau was characterized on each athlete bilaterally by measuring the medial and lateral tibial plateau slopes, coronal tibial slope, and the depth of the medial tibial plateau. Comparisons between knees of the same person were made with paired t tests, and associations with injury risk were assessed by conditional logistic regression analysis of ACL-injured and control participants. Results: Controls exhibited side-to-side symmetry of subchondral bone geometry, while the ACL-injured athletes did not, suggesting that the ACL injury may have changed the subchondral bone geometry. Therefore, the uninjured knees of the ACL-injured athletes and the corresponding limbs of their matched controls were used to assess associations with injury risk. Analyses of males and females as a combined group and females as a separate group showed a significant association between ACL injury risk and increased posterior-inferior directed slope of the lateral tibial plateau slope. This relationship was not apparent when males were analyzed as a group. Multivariate analyses indicated that these results were independent of the medial tibial plateau slope, coronal tibial slope, and depth of the medial tibial plateau, which were not associated with ACL injury. Conclusion: There is a 21.7% increased risk of noncontact ACL injury with each degree increase of the lateral tibial plateau slope among females but not among males. The medial tibial plateau slope, coronal tibial slope, and depth of the medial tibial plateau were not associated with risk of injury for females or males.

A Preliminary In Vivo Assessment of Anterior Cruciate Ligament-Deficient Knee Kinematics With the KneeM Device: A New Method to Assess Rotatory Laxity Using Open MRI.

Background:Methods of objectively measuring rotational knee laxity are either experimental or difficult to use in daily practice. A new method has been developed to quantitatively assess rotatory laxity using an open MRI system and new tool, the KneeM device.Purpose/Hypothesis:To perform a preliminary evaluation of a novel knee rotation measurement device to assess knee kinematics during flexion in an MRI field, in both anterior cruciate ligament (ACL)–deficient and healthy contralateral knees. The hypothesis was that the KneeM device would allow in vivo reproduction and analysis of knee kinematics during flexion in healthy and ACL-deficient knees.Study Design:Controlled laboratory study.Methods:Ten subjects (7 men and 3 women; mean age ± standard deviation, 32.3 ± 9.4 years) with ACL-deficient knees and contralateral uninjured knees participated in the study. An open MRI was performed with the KneeM device at a mean 4.9 months (range, 3.0-7 months) after ACL injury. The device exerted on the knee an anterior drawer force of 100 N, with an internal rotation of 20°, through the range of flexion (0°, 20°, 40°, and 60°). Both ACL-deficient and healthy contralateral knees were analyzed using the Iwaki method.Results:There was no statistical difference of anterior translation in the medial compartment between intact and ACL-deficient knees at all degrees of flexion. However, significant differences in the anterior translation of the lateral compartment were observed between ACL-deficient and intact contralateral knees at 0° and 20° of flexion (P = .005 and P = .002, respectively). Between 20° and 40°, the lateral plateau of ACL-deficient knees translated 7.7 mm posteriorly, whereas the medial compartment remained stable, reflecting a sudden external rotation of the lateral plateau under the femoral condyle.Conclusion:This preliminary study suggests that measurement of tibiofemoral movements in both compartments during flexion using the KneeM device was useful for quantifying rotatory laxity in ACL-deficient knees. Moreover, this device seemed to allow a “mechanized pivot shift” and allowed reproduction of the “pivot” phase in the MRI field between 20° and 40° of flexion.Clinical Relevance:This device could be used for diagnostic purposes or to investigate the outcomes of ACL reconstructions.

Changes of Muscle Mechanics Associated With Anterior Cruciate Ligament Deficiency and Reconstruction

Isometric and isokinetic knee strength deficits were examined on patients with anterior cruciate ligament (ACL) injury before and after ACL reconstruction. Muscle strengths of the uninjured and injured knees were measured from an ACL injured (n = 12) and a control (n = 15) group. Five isometric (10, 30, 50, 70, and 90° of knee flexion) and 5 isokinetic (50, 100, 150, 200, and 250°·s) strengths of quadriceps and hamstrings were measured prereconstruction and postreconstruction (3 and 6 months). Compared with the controls, the uninjured knee showed normal strength and patterns of length-tension and force-velocity relationships. Compared with the uninjured knee, the injured knees showed a generally 25-30% decrease in quadriceps and hamstrings strength with normal patterns of length-tension and force-velocity relationships. By 3 months of reconstruction, weakness of quadriceps of the injured knees was exacerbated, particularly at lengthened positions (∼ 40% of the uninjured knees at knee flexion 70 and 90°) and at slower velocities (∼35% of the uninjured knees at the 50 and 100°·s, p < 0.05), with flattened patterns of mechanical output. By 6 months of reconstruction, the quadriceps of the injured knees still showed significant weakness (∼50% of the uninjured knees) in both contraction types (isometric at knee flexion 90° and isokinetic at 50°·s, p < 0.05). The hamstrings of the injured knees had not shown significant changes after reconstruction. A strengthening program placing emphasis on greater knee flexion angles and slower movement speed with sufficient training duration post ACL reconstruction is recommended because of long-lasting and exacerbated weakness during 3 and 6 months postreconstruction.

Mesenchymal Stem Cells in Synovial Fluid Increase After Meniscus Injury

BackgroundAlthough relatively uncommon, spontaneous healing from a meniscus injury has been observed even within the avascular area. This may be the result of the existence of mesenchymal stem cells in synovial fluid.Questions/purposesThe purpose of this study was to investigate whether mesenchymal stem cells existed in the synovial fluid of the knee after meniscus injury.MethodsSynovial fluid was obtained from the knees of 22 patients with meniscus injury just before meniscus surgery and from 8 volunteers who had no history of knee injury. The cellular fraction of the synovial fluid was cultured for 14 days followed by analysis for multilineage potential and presentation of surface antigens characteristic of mesenchymal stem cells. Colony-forming efficiency and proliferation potential were also compared between the two groups.ResultsCells with characteristics of mesenchymal stem cells were observed in the synovial fluid of injured knees to a much greater degree than in uninjured knees. The colony-forming cells derived from the synovial fluid of the knee with meniscus injury had multipotentiality and surface epitopes identical to mesenchymal stem cells. The average number of colony formation, obtained from 1 mL of synovial fluid, in meniscus-injured knees was 250, higher than that from healthy volunteers, which was 0.5 (p < 0.001). Total colony number per synovial fluid volume was positively correlated with the postinjury period (r = 0.77, p < 0.001).ConclusionsMesenchymal stem cells were found to exist in synovial fluid from knees after meniscus injury. Mesenchymal stem cells were present in higher numbers in synovial fluid with meniscus injury than in normal knees. Total colony number per synovial fluid volume was positively correlated with the postinjury period.Clinical RelevanceOur current human study and previous animal studies suggest the possibility that mesenchymal stem cells in synovial fluid increase after meniscus injury contributing to spontaneous meniscus healing.

Principal component modeling of isokinetic moment curves for discriminating between the injured and healthy knees of unilateral ACL deficient patients

Bilateral knee strength evaluations of unilateral anterior cruciate ligament (ACL) deficient patients using isokinetic dynamometry are commonly performed in rehabilitation settings. The most frequently-used outcome measure is the peak moment value attained by the knee extensor and flexor muscle groups. However, other strength curve features may also be of clinical interest and utility. The purpose of this investigation was to identify, using Principal Component Analysis (PCA), strength curve features that explain the majority of variation between the injured and uninjured knee, and to assess the capabilities of these features to detect the presence of injury. A mixed gender cohort of 43 unilateral ACL deficient patients performed 6 continuous concentric knee extension and flexion repetitions bilaterally at 60°s−1 and 180°s−1 within a 90° range of motion. Moment waveforms were analyzed using PCA, and binary logistic regression was used to develop a discriminatory decision rule. For all directions and speeds, a statistically significant overall reduction in strength was noted for the involved knee in comparison to the uninvolved knee. The discriminatory decision rule yielded a specificity and sensitivity of 60.5% and 60.5%, respectively, corresponding to an accuracy of ∼62%. As such, the curve features extracted using PCA enabled only limited clinical usefulness in discerning between the ACL deficient and contra lateral, healthy knee. Improvement in discrimination capabilities may perhaps be achieved by consideration of different testing speeds and contraction modes, as well as utilization of other data analysis techniques.

Anterior Cruciate Ligament Injury and Radiologic Progression of Knee Osteoarthritis

Background: Knee osteoarthritis after anterior cruciate ligament (ACL) injury has previously been reported. However, there has been no meta-analysis reporting the development and progression of osteoarthritis. Purpose: We present the first meta-analysis reporting on the development and progression of osteoarthritis after ACL injury at a minimum mean follow-up of 10 years, using a single and widely accepted radiologic classification, the Kellgren & Lawrence classification. Study Design: Meta-analysis. Method: Articles were included for systematic review if they reported radiologic findings of ACL-injured knees and controls using the Kellgren & Lawrence classification at a minimum mean follow-up period of 10 years. Appropriate studies were then included for meta-analysis. Results: Nine studies were included for systematic review, of which 6 studies were further included for meta-analysis. One hundred twenty-one of 596 (20.3%) ACL-injured knees had moderate or severe radiologic changes (Kellgren & Lawrence grade III or IV) compared with 23 of 465 (4.9%) uninjured ACL-intact contralateral knees. After ACL injury, irrespective of whether the patients were treated operatively or nonoperatively, the relative risk (RR) of developing even minimal osteoarthritis was 3.89 (P < .00001), while the RR of developing moderate to severe osteoarthritis (grade III and IV) was 3.84 (P < .0004). Nonoperatively treated ACL-injured knees had significantly higher RR (RR, 4.98; P < .00001) of developing any grade of osteoarthritis compared with those treated with reconstructive surgery (RR, 3.62; P < .00001). Investigation of progression to moderate or severe osteoarthritis (grade III or IV only) after 10 years showed that ACL-reconstructed knees had a significantly higher RR (RR, 4.71; P < .00001) compared with nonoperative management (RR, 2.41; P = .54). It was not possible to stratify for return to sports among the patients undergoing ACL reconstruction. Conclusion: Results support the proposition that ACL injury predisposes knees to osteoarthritis, while ACL reconstruction surgery has a role in reducing the risk of developing degenerative changes at 10 years. However, returning to sports activities after ligament reconstruction may exacerbate the development of arthritis.

The effect of thigh muscle activity on anterior knee laxity in the uninjured and anterior cruciate ligament-injured knee

The main purpose of this study was to describe the nature of the relationship between hamstring muscle activity and anterior knee laxity. This was a cross-sectional study. Anterior knee laxity was measured at 133N and manual maximal forces using the KT2000 knee arthrometer, in 8 ACL-injured and 13 uninjured individuals. Electromyographic activity of the lateral hamstrings was measured during laxity testing. Subjects contracted the hamstrings during anterior knee laxity testing at eight predetermined levels of maximal voluntary isometric contraction. Volitional contraction of the lateral hamstrings reduced anterior knee laxity logarithmically for both the 133N and manual maximal tests in both the ACL-injured and uninjured knees. A simple linear regression model, with the log of percentage of maximum lateral hamstrings activity as the sole predictor, explained approximately 70-80% of the variation in anterior knee laxity. Both ACL-injured and uninjured subjects reduced anterior knee laxity at the same rate with increases in muscle activity. However, initial lateral hamstrings muscle activity had a greater effect on percentage anterior knee laxity scores in the ACL-injured as compared to the uninjured knee. Lateral hamstrings activity reduces anterior knee laxity in a nonlinear manner, whereby the initial lower level of activation produces the greatest change in anterior knee laxity. Therefore, hamstrings muscle activity must be monitored during anterior knee laxity testing.

Prospective Evaluation on the Incidence of Secondary Meniscus and Cartilage Injuries Following Non-Operative Treatment of Anterior Cruciate Ligament Injuries in Skeletally Immature Children Using 3.0T MRI

In this prospective cohort study the incidence of secondary meniscus and cartilage injuries was found to be low (4.8%) in 40 skeletally immature children with a primary non-operatively treated ACL rupture over a period of 1.7 years (±0.1 years), using 3.0T MR images reviewed by two independent MRI-radiologists. There is solid evidence that persons with a rupture of the anterior cruciate ligament (ACL) will have increased risk of knee osteoarthritis in the long term, and that additional injury to menisci and cartilage further increase the risk. The prevalence of meniscus injuries in skeletally immature children who undergo early ACL reconstruction is reported between 35% and 69%. No prospective study has investigated whether advocating a non-operative treatment algorithm for children with ACL rupture will lead to an increase of secondary injuries. The Purpose of this study was to prospectively investigate the incidence of new meniscus and cartilage injuries in skeletally immature children with a known ACL rupture. The uninjured knee of the children was the control knee. Forty consecutive skeletally immature children were enrolled in a prospective cohort study. The inclusion criteria were a traumatic ACL injury in a child with open physis sustained at age 12 years of age and younger. Fourteen girls (35%) and 26 boys (65%) with an average age of 11.0 years (±1.4 years) at the time of injury were examined using 3.0T MRI of both knees at two occasions; MRI1: 2.2 years (±1.4 years) after injury, and MRI2: 1.7 years (±0.1 years) after MRI1. The images were read by two independent MRI-radiologists. The prevalence and incidence of meniscus and cartilage injuries were calculated using SPSS. The prevalence of meniscus and cartilage injuries in knees with ACL rupture was 39.0% (medial, n=6; lateral, n=7; medial + lateral, n=3) and 12.2% respectively at MRI1, and 41.5% (medial, n=7; lateral, n=7; medial + lateral, n=3) and 12.2% at MR2. The incidence of new meniscus injuries was 4.8% (1 new medial and 1 new lateral, while 1 lateral was normalized). At MRI1 10 (24.4%) knees had undergone ACL reconstruction, and at MRI2 13 (31.7%) were reconstructed. The prevalence of meniscus and cartilage injuries in the contralateral knee was 10.3% and 2.6%, respectively at MRI1, and 10.3% and 5.1% at MRI2. The incidence of new meniscus injuries in the contralateral knee was zero, while the incidence of new cartilage injuries was 2.5%. The incidence of new meniscus and cartilage injuries was low in ACL injured knees over a period of 1.7 years in skeletally immature children. The overall prevalence of meniscus injuries was comparable to previous studies. The results of the present study suggest that a non-operative treatment algorithm should be considered for skeletally immature children with ACL rupture, with regard to the incidence of secondary meniscus and cartilage injuries.

Geometric profile of the tibial plateau cartilage surface is associated with the risk of non‐contact anterior cruciate ligament injury

The purpose of this study was to determine if geometry of the articular surfaces of the tibial plateau is associated with non-contact anterior cruciate ligament (ACL) injury. This was a longitudinal cohort study with a nested case-control analysis. Seventy-eight subjects who suffered a non-contact ACL tear and a corresponding number of controls matched by age, sex, and sport underwent 3 T MRI of both knees. Surface geometry of the tibial articular cartilage was characterized with polynomial equations and comparisons were made between knees on the same person and between ACL-injured and control subjects. There was no difference in surface geometry between the knees of the control subjects. In contrast, there were significant differences in the surface geometry between the injured and normal knees of the ACL-injured subjects, suggesting that the ACL injury changed the cartilage surface profile. Therefore, comparisons were made between the uninjured knees of the ACL-injured subjects and the corresponding knees of their matched controls and this revealed significant differences in the surface geometry for the medial (p < 0.006) and lateral (p < 0.001) compartments. ACL-injured subjects tended to demonstrate a posterior-inferior directed orientation of the articular surface relative to the long axis of the tibia, while the control subjects were more likely to show a posterior-superior directed orientation.

Biomechanical Characteristics of 3 Pivot-Shift Maneuvers for the Anterior Cruciate Ligament–Deficient Knee

Background: A disadvantage of pivot-shift maneuvers is that the examiner has to subjectively evaluate the degree of pivot shift observed. It is unknown whether the various maneuvers are biomechanically identical. Purpose: To compare biomechanical features of 3 clinical maneuvers for the anterior cruciate ligament (ACL)–deficient knee: the pivot-shift test, the jerk test, and the N-test. Study Design: Controlled laboratory study. Methods: A total of 28 patients with an isolated ACL injury were examined by use of 3 pivot-shift maneuvers (pivot-shift test, jerk test, and N-test). An electromagnetic sensor system was used to evaluate the 3-dimensional knee kinematics of each patient’s injured and uninjured knees during each maneuver. Peak coupled anterior tibial translation (pCAT) and maximal acceleration of posterior translation (APT) were measured relative to results during a flexion-extension motion in each test. Results: The pCAT of the pivot-shift test was significantly greater than that of both the jerk test and the N-test (P = .0020 and P < .0001, respectively); there was no statistical difference in pCAT between the jerk test and the N-test. The APT of the N-test was significantly greater than that of both the pivot-shift test and the jerk test (P < .0001), while there was no statistical difference between the pivot-shift and the jerk tests. There was no correlation between pCAT and APT in each test. Conclusion: The pivot-shift test, jerk test, and N-test have different biomechanical characteristics to induce the pivot-shift phenomenon in the ACL-deficient knee. The pivot-shift test produced the largest side-to-side difference in pCAT, whereas the N-test provoked the largest side-to-side difference in APT. Clinical Relevance: The biomechanical differences in pivot-shift maneuvers are caused by technical differences, and clinicians should understand these biomechanical differences while practicing the maneuvers. The electromagnetic sensor system is clinically useful for quantifying the pivot-shift phenomenon.

Association between varus alignment and post-traumatic osteoarthritis after anterior cruciate ligament injury

To investigate the association between varus alignment and post-traumatic osteoarthritis (OA) after an anterior cruciate ligament (ACL) injury. One hundred subjects with an acute complete ACL tear were followed for 15 years. Anterior-posterior radiographs of the tibiofemoral joint were obtained with a knee flexion of 20°, and the patellofemoral joint was examined with skyline view at 50° knee flexion. Joint space narrowing and osteophytes were graded in the tibiofemoral and patellofemoral joints in the injured (ACL) and uninjured knee according to the radiographic atlas of the Osteoarthritis Research Society International. The alignment of the uninjured, contralateral knee was measured at follow-up, using full-limb radiographs of leg with the knee in full extension. Alignment was expressed as the hip-knee-ankle (HKA) angle. Alignment was defined as valgus (HKA ≤178°), neutral (179°-181°) or varus (≥182°). Data from 68 subjects were included in the analysis. Varus alignment of the uninjured knee at follow-up appeared to be associated with OA of the injured knee 15 years after an ACL injury (odds ratio (95% confidence interval) 3.9 (1.0-15.8, p = 0.052)). Varus alignment of the uninjured knee at follow-up may be associated with OA of the injured knee 15 years after an ACL injury. II.

ACL reconstruction with physiological graft tension by intraoperative adjustment of the anteroposterior translation to the uninjured contralateral knee

Fixation of anterior cruciate ligament (ACL) substitutes with non-physiological anteroposterior translation (APT) worsens outcome. The aim was to present a technique for physiological APT adjustment of the transplant in ACL reconstruction and its outcome at midterm. In a consecutive series of 28 patients (age 32 ± 11 years, 24 male), chronic ACL deficiency was treated by bone-patella-tendon-bone reconstruction. Transplant APT was adjusted to that of the contralateral uninjured ACL, measured 3, 6, and 12 months postoperatively using the Rolimeter. At a median follow-up of 5.3 years (3-8 years), 82% of the patients were re-evaluated with APT measurement and using IKDC-, Tegner-, Lysholm-Scores, conventional radiographs and MRI. No differences in APT (mean ± SD) between uninjured and reconstructed knees were observed after adjustment (6 ± 1 versus 6 ± 1 mm, n.s.). Three months postoperatively, a statistically significant increase in APT (7 ± 1 mm) and a further increase at midterm (9 ± 2 mm) were observed. Patients scored "normal" or "nearly normal", respectively, in 79% (IKDC) and 4 (3-9) points (Tegner; median, range) or 89 ± 9 points (Lysholm; mean ± SD). Radiological evaluation showed no, minimal or moderate joint degeneration in 5, 20 and 75% of patients, respectively. MRI confirmed intact ACL transplants in all patients. ACL reconstruction using the presented technique was considered successful, as patients did not suffer from subjective instability, radiographic analysis did not provide evidence for graft rupture at midterm. However, APT increase and occurrence of degenerative changes in reconstructed knees at the midterm might not be prevented even by restoration of a physiological APT in ACL reconstruction. The Rolimeter can be used for quick and easy intraoperative indirect control of the applied tension to the ACL transplant by measuring the APT to obtain physiological tensioning resulting in a satisfying outcome at midterm. IV.

Surgical Management of Traumatic Knee Dislocation With Posterolateral Corner Injury

To evaluate the results of our method of surgical treatment of traumatic knee dislocation with injury to the posterolateral corner by use of a standardized protocol. Twenty-five consecutive patients presented with a grossly dislocated or reduced knee. Five of these patients were not included in this series. The remaining 20 patients were treated by primary arthroscopic reconstruction. The anterior cruciate ligament (ACL) was reconstructed using gracilis tendon reinforced with artificial ligament (Ligament Augmentation and Reconstruction System [LARS] ligament); the posterior cruciate ligament (PCL) was reconstructed with semitendinosus tendon and reinforced with LARS ligament; and the posterolateral corner was treated using the gracilis and semitendinosus tendons from the uninjured knee. Twenty patients returned for subjective and objective evaluation at a minimum of 24 months after surgery. Early mobilization through continuous and active exercise was started on the fourth day postoperatively. At a mean follow-up of 44 months, the mean Lysholm score was 90 points, the mean score on the survey of daily activities was 90 points, and the sports activities score on the knee outcome survey averaged 80 points. By the rating of Meyers etal. the results were excellent in 6 patients, good in 10 patients, fair in 3 patients, and poor in one patient. The final International Knee Documentation Committee (IKDC) rating was not normal in any knee. The mean loss of extension was 2° (range, 0° to 3°) and loss of flexion was 12° (range, 10° to 15°). By using the described method of arthroscopically assisted reconstruction of the cruciate ligaments and the posterolateral corner, 80% of the patients had good subjective results and functional stability, and according to the IKDC scale, 45% of knees were nearly normal, 45% were abnormal, and 10% were severely abnormal. No patient's rating returned to normal. Level IV, therapeutic case series.

Proprioceptive changes in the contralateral knee joint following anterior cruciate injury

Loss of proprioception following an anterior cruciate ligament (ACL) injury has been well documented. We evaluated proprioception in both the injured and the uninjured limb in 25 patients with ACL injury and in 25 healthy controls, as assessed by joint position sense (JPS), the threshold for the detection of passive movement (TDPM) and postural sway during single-limb stance on a force plate. There were significant proprioceptive deficits in both ACL-deficient and uninjured knees compared with control knees, as assessed by the angle reproduction test (on JPS) and postural sway on single limb stance. The degree of loss of proprioception in the ACL-deficient knee and the unaffected contralateral knee joint in the same patient was similar. The TDPM in the injured knee was significantly higher than that of controls at 30° and 70° of flexion. The TDPM of the contralateral knee joint was not significantly different from that in controls. Based on these findings, the effect of proprioceptive training of the contralateral uninjured knee should be explored.

Treatment for acute anterior cruciate ligament tear: five year outcome of randomised trial

Objective To compare, in young active adults with an acute anterior cruciate ligament (ACL) tear, the mid-term (five year) patient reported and radiographic outcomes between those treated with rehabilitation plus...

Patella rings for treatment of patellar fracture

To evaluate a new fixation technique for patellar fracture using patella rings. A total of 75 patients (average age of 51.3years) with comminuted or transverse patellar fractures were treated by fixation with patella rings. The Böstman scores at the time of bone union and at 12months postoperatively were recorded, as was the degree of pain on a visual analogue scale (VAS), the range of motion of the knee at 12months postoperatively, and any signs of postoperative complications. The average Böstman scores for patients in the transverse fracture group were 25.2 and 29.4 at 3 and 12months postoperatively, respectively, while the scores for patients in the comminuted fracture group were 27.6 and 28.7, at the same time points. Böstman scores were graded as excellent and good in more than 90% for patients with either a transverse or comminuted fracture. At the time of 12months after surgery, the VAS score for patients with comminuted fractures was 0.38, whereas the score for patients in the transverse fracture group was 0.35. No statistically significant difference was found in the range of motion between the affected and uninjured knee at 12months after surgery for patients in both groups (P>0.05). This new fixation technique using a patella ring resulted in good outcomes for both transverse fracture and comminuted fracture and is beneficial for patients wishing to commence early functional activity.

The Intact Posterior Cruciate Ligament Not Only Controls Posterior Displacement but Also Maintains the Flexion Gap

The PCL is a strong stabilizer of the knee and provides posterior stability to the tibia. However, sagittal alignment of the PCL with the knee at 90° flexion suggests the PCL might play a role not only in posterior stabilization but also in maintaining the flexion gap. We determined whether the intact PCL helps maintain the flexion gap. We examined axial radiographs and gravity sag views of 17 patients with chronic isolated unilateral PCL injury. The flexion gap was defined as the mean value of the medial and lateral distances between the femoral and tibial bones on the axial radiograph. Increase in the flexion gap and posterior laxity were determined by comparing the patients' injured and contralateral uninjured knees. The flexion gap of PCL injured knees (median, 7.5 mm; range, 5.3-11.5 mm; medial median, 6.2 mm; medial range, 3.7-8.3 mm; lateral median, 7.9 mm; lateral range, 5.3-11.5 mm) was larger than that seen in uninjured knees (median, 5.0 mm; range, 4.0-7.6 mm; medial median, 4.6 mm; medial range 3.4-7.1 mm; lateral median, 5.6; lateral range, 4.5-11.2 mm). The increment in the medial distance was similar to that in the lateral distance. Posterior laxity of injured knees was 9.1 (median); 5.4 to 15.2 (range) mm greater than that of uninjured knees. We found no correlation between posterior laxity and the flexion gap increment. Our data suggest the intact PCL controls posterior displacement and maintains the flexion gap.

Altered loading in the injured knee after ACL rupture

Articular loading is an important factor in the joint degenerative process for individuals with anterior cruciate ligament (ACL) rupture. Evaluation of loading for a population that exhibits neuromuscular compensation for injury requires an approach which can incorporate individual muscle activation strategies in its estimation of muscle forces. The purpose of this study was to evaluate knee joint contact forces for patients with ACL deficiency using an EMG-driven modeling approach to estimate muscle forces. Thirty athletes with acute, unilateral ACL rupture underwent gait analysis after resolving range of motion, effusion, pain, and obvious gait impairments. Electromyography was recorded bilaterally from 14 lower extremity muscles and input to a musculoskeletal model for estimation of muscle forces and joint contact forces. Gait mechanics were consistent with previous reports for individuals with ACL-deficiency. Our major finding was that joint loading was altered in the injured limb after acute ACL injury; patients walked with decreased contact force on their injured knee compared to their uninjured knee. Both medial and lateral compartment forces were reduced without a significant change in the distribution of tibiofemoral load between compartments. This is the first study to estimate medial and lateral compartment contact forces in patients with acute ACL rupture using an approach which is sensitive to individual muscle activation patterns. Further work is needed to determine whether this early decreased loading of the injured limb is involved in the development of osteoarthritis in these patients.