Significant Difference In Laxity Research Articles

High Prevalence of Persistent Measurable Postoperative Knee Joint Laxity in Patients with Tibial Plateau Fractures Treated by Open Reduction and Internal Fixation (ORIF).

The development of post-traumatic osteoarthrosis after tibial plateau fracture (TPF) is multifactorial and can only be partially influenced by surgical treatment. There is no standardized method for assessing pre- and postoperative knee joint laxity. Data on the incidence of postoperative laxity after TPF are limited. The purpose of this study was to quantify postoperative laxity of the knee joint after TPF. Fifty-four patients (mean age 51 ± 11.9 years) were included in this study. There was a significant increase in anterior-posterior translation in 78.0% and internal rotation in 78.9% in the injured knee when compared to the healthy knee. Simple fractures showed no significant difference in laxity compared to complex fractures. When preoperative ligament damage and/or meniscal lesions were present and surgically treated by refixation and/or bracing, patients showed higher instability when compared to patients without preoperative ligament and/or meniscal damage. Patients with surgically treated TPF demonstrate measurable knee joint laxity at a minimum of 1 year postoperatively. Fracture types have no influence on postoperative laxity. This emphasizes the importance of recognizing TPF as a multifaceted injury involving both complex fractures and damage to multiple ligaments and soft tissue structures, which may require further surgical intervention after osteosynthesis.

Outcomes Following Bone-patellar Tendon-Bone Anterior Cruciate Ligament Reconstruction In Patients <30 Years: Allograft Vs. Autograft

PURPOSE: The purpose of this study was to investigate differences in failure rates and functional outcomes between patients <30 years of age that underwent allo- or autograft Bone-Patellar Tendon-Bone (BPTB) ACLR. METHODS: All patients aged 16-30 years who underwent a BPTB allo- or autograft ACLR with bioabsorbable interference screws by a single surgeon (1995-2019) were included. Exclusion criteria were follow-up <2 years, osteochondral drilling, revision ACLR, and multi-ligamentous injuries. The allograft was always <5 years than patient age and not terminally irradiated. Meniscal repairs were completed as necessary. All patients completed a decelerated, conservative rehab program with required bracing for 3 months and return to pivoting sports >6 months. An independent physical exam including knee ROM and stability testing, (manual max KT-1000, Lachman, pivot shift) was performed. Patients completed Lysholm, IKDC, Tegner and pain Visual Analogue Score (VAS) to assess clinical outcomes. Failure was defined as positive Lachman or pivot shift test or MRI evidence of re-tear. RESULTS: 13 patients with BPTB allograft (5 male/8 female; 24.3 ± 4.0 years) and 35 patients with BPTB autograft (28 males/7 females; 22.3 ± 4.2 years) ACLR were included (p = 0.136). Average follow-up was 11.7 ± 3.9 years in the allograft group and 13.9 ± 5.9 years in the autograft group (p = 0.685). There were no significant differences in functional outcomes between groups (Lysholm: p = 0.226; IKDC: p = 0.107; Tegner: p = 0.610). There was no significant difference in laxity between groups (KT-1000 30 lbs: p = 0.131; manual maximum: p = 0.416; side to-side difference 30 lbs: p = 0.310; side-to-side difference manual max: p = 0.472). All patients returned to preoperative sports (Tegner score ≥ 5). Overall failure rate was 1.8% (1/48) with 1 failure in the autograft group (p = 0.548). CONCLUSION: In this cohort of young patients, no difference in failure rate was seen between allograft and autograft. At a mean of >10-year follow-up, laxity and all patient reported outcomes were not different between the groups. Careful selection of an allograft for use in ACLR and a decelerated rehabilitation program can be a good alternative in young patients >30 years to return to preoperative sports with no evidence of increased failure rates in this cohort.

The Addition of Suture Tape to the Hamstring Graft Construct Does Not Reduce Instrumented Knee Laxity Following ACL Reconstruction

PurposeTo establish the effect of the addition of suture tape to the hamstring graft construct through measurement of instrumented sagittal plane knee laxity at 6 months after anterior cruciate ligament reconstruction (ACLR).MethodsA retrospective analysis was undertaken of a consecutive series of primary ACLR performed between May 2017 and June 2019. Patients with concomitant or historic contralateral knee injury were excluded. Suture tape was included in the graft construct from the midpoint of the study period (May 2018). Sagittal plane knee laxity was quantified using the KT2000 arthrometer at 6 postoperative months. Mean side-to-side differences in sagittal plane laxity between the operated and contralateral, uninjured knees were compared for grafts with and without suture tape. Additional outcomes included comparison between suture tape application techniques (graft reinforcement versus augmentation), comparison between suture tape with and without iliotibial band (ITB) tenodesis and documentation of complications necessitating further surgery.ResultsA total of 169 patients were eligible for inclusion. Seventy-two grafts included suture tape and 84 patients underwent concomitant ITB tenodesis. There was no significant difference in mean laxity between grafts containing suture tape (mean difference: 1.2 mm, SD: 2.6 mm) and those without (mean difference: 1.3 mm, SD: 2.1 mm), P = .83 (CI −.92 to 1.13). Neither were there significant differences in laxity when using suture tape with concomitant ITB tenodesis (mean difference: 1.1 mm, SD: 2.1 mm), P = .75 (CI −.79 to 1.09), or when comparing techniques: graft reinforcement (mean difference .9 mm, SD 2.6 mm); graft augmentation (mean difference: 1.5 mm, SD: 2.5 mm) P = .52 (CI −2.29 to 1.16). There were no complications associated with suture tape.ConclusionsThe addition of suture tape to an autologous hamstring graft construct did not reduce instrumented sagittal knee laxity in the first 6 months after ACL reconstruction. As such, the clinical relevance of its use remains unknown.Level of EvidenceLevel III, retrospective cohort study.

Fifteen Year Prospective Comparison of Patellar & Hamstring Tendon Grafts for ACL Reconstruction

Objective:This prospective longitudinal study compares isolated endoscopic ACL reconstruction utilizing 4-strand hamstring tendon (HT) or patellar tendon (PT) autograft over a 15-year period with respect to clinical outcomes and the development of osteoarthritis.Method:90 consecutive patients with isolated ACL rupture were reconstructed with a PT autograft and 90 patients received HT autograft, with an identical surgical technique. Patients were assessed at 2, 5, 7, 10 and 15 years. Assessment included the IKDC Knee Ligament Evaluation including radiographic evaluation, KT1000, kneeling pain, and clinical outcomes.Results:Subjects who received the PT graft had significantly worse outcomes at 15 years for the variables of radiologically detectable osteoarthritis (p=0.001), motion loss (p=0.02), single leg hop test (p=0.002), participation in strenuous activity (p=0.03), knee related decrease in activity level (p=0.002) and kneeling pain (p=0.03). There was no significant difference between the HT and PT groups in overall IKDC grade (p=0.28). ACL graft rupture occurred in 16% of HT group and 8% of the PT group (p=0.10). Contralateral ACL rupture occurred in significantly more PT patients (24%) than HT patients (12%) (p=0.03).Conclusion:Significant differences have developed at 15 years after surgery which were not seen at earlier reviews. Compared to the HT Group, the PT group had significantly worse outcomes with respect to radiological osteoarthritis, range of motion and functional tests but no significant difference in laxity was identified. There was a high incidence of ACL injury after reconstruction, to both the reconstructed and the contralateral knee.

Double-bundle versus single-bundle anterior cruciate ligament reconstructions: a prospective, randomized study with 2-year follow-up

This prospective, randomized study was conducted to compare the short-term results of arthroscopic double-bundle with single-bundle anterior cruciate ligament (ACL) reconstruction. One hundred and eight patients with a symptomatic ACL rupture were randomized to either double-bundle (Group DB) or single-bundle (Group SB) ACL reconstruction. Follow-up was conducted at 6, 12, 18 and 24 months postoperatively. At the 24-month follow-up, 94 of the 108 patients (87%) were available for evaluation. The rotational stability, as evaluated by pivot shift test, was significantly superior in the Group DB to that in the Group SB. No significant difference with regard to ACL revisions, total flexion work, mean peak flexion torque and extension work between the groups was detected. There was no significant difference between the groups in terms of the Tegner activity score, the knee injury and osteoarthritis outcome score, the Lysholm functional score, anterior knee pain or mobility, subjective knee function. In addition, no significant difference in laxity on the Lachman test or the KT-1000 maximum manual force test was investigated. All the results were significantly more satisfactory at each follow-up period than preoperatively, in both groups. Both SB- and DB-ACL reconstruction resulted in satisfactory subjective outcome and objective stability. Both these techniques can therefore be considered as suitable alternatives for ACL reconstruction. Moreover, as it seems to be according to the pivot shift test, the risk for the development of degenerative changes of the knee joint in a long run could be smaller in the Group DB.

Interval Arthrometric Comparison of Anterior Cruciate Ligament Reconstruction Using Bone–Patellar Tendon–Bone Autograft Versus Allograft

Background: There is little information regarding the incremental changes in the postoperative laxity of patellar tendon (PT) autografts versus allografts in anterior cruciate ligament (ACL) reconstruction. Hypotheses: (1) There would be no significant increase in laxity between 6 weeks and 1 year postoperatively with PT autografts or allografts, (2) there would be no significant difference in laxity between PT autografts and allografts, (3) there would not be a significant difference in laxity between nonirradiated and low dose–irradiated PT allograft tissues, and (4) the physical examination findings would correlate with the instrumented laxity outcomes. Study Design: Cohort study; Level of evidence, 3. Methods: A retrospective review of 238 ACL-deficient patients who underwent single-incision endoscopic ACL reconstruction with a PT autograft (n = 132) or allograft (n = 106; 58 irradiated and 48 nonirradiated) from a single surgeon was made looking at data from preoperatively and from 6 weeks to 1 year postoperatively. The objective measurements of ligament integrity included range of motion, Lachman test, pivot-shift test, and KT-1000 arthrometer instrumented laxity examination. Failure was defined as arthrometric side-to-side differences (maximum manual difference) ≥3 mm or a positive pivot shift. Statistical significance was defined as P < .05. Results: There were no differences in postoperative examination findings or instrumented laxity between PT autografts and allografts (irradiated or nonirradiated) in either subgroup. The postoperative improvement based on the Lachman examination, pivot-shift test, and arthrometric data in all study groups was significant (P < .001) in 98% (autograft: n = 130; allograft: n = 104) of patients, and arthrometric failure correlated with failure by physical examination. There was no significant change in graft laxity, as measured by KT-1000 arthrometer, from 6 weeks to 1 year postoperatively for 98% of patients. Finally, there was no statistical correlation in instrumented laxity results for either the autograft or allograft group with reference to age, gender, concurrent meniscectomy, meniscal repairs, interval to surgery, postoperative patellar pain, time to surgery, or irradiated versus nonirradiated allograft. Conclusion: Laxity is not increased after the initial 6 weeks for either PT allograft or autograft constructs during the first postoperative year. There was no correlation between age, gender, concomitant injury, interval to surgery, or radiation of the graft with instrumented laxity results. Furthermore, our arthrometric data paralleled our clinical findings of stability at follow-up.

Long-term follow-up of patellar tendon grafts or hamstring tendon grafts in endoscopic ACL reconstructions

Several studies compare the short- and long-term results of anterior cruciate ligament (ACL) reconstruction using bone-patellar tendon-bone (BPTB) graft or double-looped semitendinosus and gracilis (DLSG) graft. However, no studies evaluate the long-term results of BPTB grafts fixed with metal interference screws and DLSG grafts fixed with the Bone Mulch Screw and the Washer Loc. This prospective randomized multicentre study has the null hypothesis that there is no difference in long-term outcome between the two procedures. A total of 114 patients with a symptomatic ACL rupture were randomized to reconstruction with either a BPTB graft (N=58) or a DLSG graft (N=56). Follow-up was conducted after one, two and sevenyears. At the seven-year follow-up, 102 of the 114 patients (89%) were available for evaluation; however, 16 of these by telephone-interview only. Ten patients in the BPTB group and 19 patients in the DLSG group underwent additional knee surgery (P=0.048), two and three, respectively, of these were ACL revisions (n.s.). The total flexion work was lower in the DLSG group (P=0.001). The mean peak flexion torque and extension work, however, showed no difference between the groups. No significant differences were found between the groups regarding the Tegner activity score, the Lysholm functional score, the Knee injury and osteoarthritis outcome score (KOOS), subjective knee function, anterior knee pain or mobility. There was no significant difference in laxity between the groups on the Lachman test or the KT-1,000 maximum manual force test. Both grafts and fixation methods resulted in satisfactory subjective outcome and objective stability. Both these methods can therefore be considered as suitable alternatives for ACL reconstructions. II.

Joint laxity in the parents of children with temporary brittle bone disease

One controversial cause of unexplained fractures in young children is temporary brittle bone disease. Contributory factors for this disorder include the following: premature birth, twin pregnancy and diminished foetal movement. Heritable factors may also be important. Infants with findings consistent with temporary brittle bone disease were identified from clinical and medico-legal referrals. The routine evaluation of each family included examination of both parents where available for joint laxity using the nine-point Beighton scale. Of 81 children in whom both parents had been examined personally, 40 had at least one parent with a Beighton score of four or more, conventionally regarded as indicative of the hypermobility syndrome. We found no significant difference in laxity when we compared the whole group of mothers with the controls (P = 0.081). The fathers were significantly different from their control group (P = 0.013). When we compared the figures for the most flexible parent of each child, there were significant differences from control subjects both in the mothers and in the fathers (P = 0.042 and P = 0.0065, respectively). We draw attention to the likely autosomal dominant inheritance of this risk factor for temporary brittle bone disease as well as the potential value of assessing parental joint laxity in evaluating children with fractures.

Reconstruction of the coronoid using an extended prosthesis: an in vitro biomechanical study

When repair of comminuted coronoid fractures is not possible, prosthetic replacement may restore elbow stability. The purpose of this biomechanical study was to determine whether a coronoid implant with an extended tip would improve elbow stability compared with an anatomic prosthesis in the setting of collateral ligament insufficiency. Passive elbow extension was performed in 7 cadaveric arms in the varus and valgus positions and active and passive extension in the horizontal position by use of an elbow motion simulator. Varus-valgus laxity of the ulna relative to the humerus was quantified with a tracking system with a native coronoid, a 40% coronoid deficiency, an anatomic prosthesis, and an extended prosthesis, with the collateral ligaments sectioned and repaired. Laxity significantly increased after a 40% coronoid deficiency with both repaired and sectioned collateral ligaments (P ≤ .01). With the ligaments repaired, there was no significant difference in laxity between the native coronoid, the anatomic implant, or the extended implant. Ligament sectioning alone produced severe instability, with a mean laxity of 42.75° ± 11.54° (P < .01). With insufficient ligaments, the anatomic prosthesis produced no change in laxity compared with the native coronoid, whereas the extended implant significantly reduced laxity by 21.56° ± 17.70° (P = .02). An anatomic coronoid implant with ligament repair restores stability to the coronoid-deficient elbow to intact levels. In the setting of ligament insufficiency, an extended implant improves stability relative to an anatomic implant, but the elbow remains significantly less stable than an intact elbow. Studies are needed to evaluate the feasibility of these designs.

Suture-Button Versus Screw Fixation of the Syndesmosis: A Biomechanical Analysis

The treatment of ankle fractures with syndesmotic injuries associated with disruption of the deltoid ligament complex is controversial. The purpose of this study was to compare both the biomechanical and physiologic properties of suture-button fixation to the intact syndesmosis and screw fixation. Eight fresh frozen human cadaveric ankles were used in three different groups. One group had an intact syndesmosis and deltoid ligamentous complex and two groups had fixation of the syndesmosis after its disruption along with disruption of the deltoid ligaments. One fixation group used a suture-button and the other used a 3.5-mm tricortical syndesmotic screw. The syndesmotic gap after cycling at submaximal loads, laxity due to cycling, and fibular movement allowed in the sagittal plane were all measured and analyzed for statistical significance. The syndesmotic gap after cycling was not significantly different between the intact group (9.1 mm) and the suture-button group (8.8 mm) (p = 0.1509). The screw fixation group had a significantly smaller gap (7.9 mm) as compared to the other two groups (screw versus intact, p = 0.00004; screw versus suture-button, p = 0.0004). The intact group did not demonstrate a significant difference in laxity before (9.0 mm) and after (9.1 mm) cycling (p = 0.0670), whereas the suture-button group did have a significant difference (before, 8.01 mm; after, 8.28 mm) (p = 0.000251). The movement of the fibula in the sagittal plane was significantly greater in the suture-button group (3.17 mm) as compared to the intact group (2.77 mm) (p = 0.00554). Screw fixation allowed significantly less fibular movement in the sagittal plane (1.16 mm) as compared to the intact (p = 0.00014) and suture-button (p = 0.0000012) groups. Suture-button fixation maintained reduction after cycling with submaximal loads that compared favorably to the intact syndesmosis. It also allowed more physiologic movement of the fibula in the sagittal plane when compared to tricortical screw fixation. Syndesmotic injury fixation has traditionally used screws to provide a rigid construct in which healing can take place. We believe a less rigid fixation method, such as suture-button fixation, provides a more physiologic type of healing of the syndesmosis.

A 7-Year Follow-up of Patellar Tendon and Hamstring Tendon Grafts for Arthroscopic Anterior Cruciate Ligament Reconstruction

Background For arthroscopic anterior cruciate ligament reconstruction, the most commonly used graft constructs are either the hamstring tendon or patellar tendon. Well-controlled, long-term studies are needed to determine the differences between the 2 materials. Hypothesis There is a difference between hamstring and patellar tendon grafts in the clinical results of anterior cruciate ligament reconstructions at 7 years. Study Design Cohort study; Level of evidence, 2. Methods Two groups of 90 patients each, consecutively treated with hamstring or patellar tendon grafts, were followed and assessed at 1, 2, 5, and 7 years after surgery. Results At the 7-year review, abnormal radiographic findings were seen in 45% (24/53) of the patellar tendon group and in 14% (7/51) of the hamstring tendon group (P = .002). Although there was no significant difference between the groups in extension deficit (P= .22), the percentage of patients with an extension deficit increased significantly in the patellar tendon group from 8% at 1 year to 25% at 7 years (P= .02). No significant change was seen in the hamstring tendon group over time (P= .20). There was no significant difference in laxity between the groups on Lachman (P= .44), pivot-shift (P= .39), or instrumented (P= .44) testing. Graft rupture occurred in 4 patients from the patellar tendon group and in 9 patients from the hamstring tendon group (P= .15). Both autografts gave excellent subjective results, as evidenced by the International Knee Documentation Committee evaluation and Lysholm knee scores at 7 years. Conclusions Both hamstring and patellar tendon grafts provided good subjective outcomes and objective stability at 7 years. No significant differences in the rate of graft rupture or contralateral anterior cruciate ligament rupture were identified. Patients with patellar tendon grafts had a greater prevalence of osteoarthritis at 7 years after surgery; therefore, the authors preferred hamstring tendons as the primary graft choice in anterior cruciate ligament reconstructions.

Reconstruction du ligament croisé antérieur par greffe de tendons de la patte d’oie à un ou à deux faisceaux: Comparaison biomécanique sur genoux cadavériques

Purpose of the study We worked with cadaver specimens to evaluate control of anterior knee laxity after reconstruction of the anterior cruciate ligament (ACL) comparing double two-strand anterolateral and posteromedial reconstruction with the classical four-strand technique. We hypothesized that the double reconstruction would provide better control of anterior laxity in both flexion and extension. Material and methods Sixteen cadaver knees were randomly assigned to reconstruction technique. Anterior tibial translation was measured with an arthrometer (Rolimeter™) at maximal manual tension at 20°, 60° and 90° flexion on the intact knee, after section of the ACL and after arthroscopic reconstruction using either the classical four-strand hamstring technique or a double two-strand anteromedial and posterolateral technique. An EndoButtonCL™ was used for the femoral fixation and a interference screw with staples for the tibial fixation. Variation in the length of each construct was measured between 0° and 90° flexion. Results In the single reconstruction group, the length of the graft varied by 0.5 ± 0.7 mm between 0° and 90° flexion. In the double reconstruction group, the length varied by 0.5 ± 0.9 mm for the anteromedial construct and 3.4 ± 0.5 mm for the posterolateral construct. When studied with an intact ACL, anterior laxity of the 16 knees was 3.2 ± 1.1, 3.5 ± 1.5 and 2.6 ± 1.1 mm at 20°, 60°, and 90° respectively. After section of the ACL, laxity increased significantly at all angles: 9.4 ± 3.3, 6.1 ± 2.5 and 6.8 ± 2.9 at 20°, 60°, and 90° respectively. After classical four-strand single graft reconstruction, the residual anterior laxity was 3.7 ± 0.9, 3.1 ± 1.1, and 2.3 ± 1.6 mm at 20°, 60°, and 90° flexion. Statistical analysis using parametric or non-parametric tests as appropriate showed a significant difference in laxity at 20°, 60°, and 90° of flexion between knees with a cut ACL and knees with reconstructed ACL. At 20° flexion, residual laxity was greater after single-construct reconstruction. At 60° and 90° there was no significant difference in anterior translation of the tibia in knees with intact or reconstructed ACL. After reconstruction with the dual-construct technique, laxity was 3.4 ± 1.3, 2.6 ± 1.5, and 2.4 ± 1.2 mm at 20°, 60° and 90° flexion respectively. Laxity was significantly greater with a cut ACL than after reconstruction at 20°, 60°, and 90° flexion, but there was no significant difference in anterior translation of the tibia at 20°, 60°, and 90° flexion between knees with an intact and a reconstructed ACL. Discussion These results based on a clinical evaluation measuring anterior translation of the tibia with an arthrometer are in agreement with results in the literature using robots. Compared with the classical technique, reconstruction of the ACL with a dualconstruct technique provides a statistically significant improvement in control of anterior tibial translation at 20° of flexion. The advantage of the dual anteromedial and posteriolateral construct technique is thus not found in the control of anterior laxity but rather in control of rotation laxity. Conclusion Reconstruction of the ACL with a two-bundle graft technique provides control of anterior laxity at 20°, 60°, and 90° flexion similar to that observed in knees with an intact ACL while the single construct technique re-establishes physiological laxity at 60° and 90° only. This improved control of anterior laxity with the two-bundle reconstruction is a small improvement regarding anterior laxity, the more potential advantage concerning rotational stability.

Glenohumeral Laxity in Professional Baseball Pitchers

1405 Literature suggests that elite baseball pitchers develop acquired laxity as a result of adaptive changes to the shoulder joint capsule from throwing. Capsular laxity has been implicated in the etiology of micro-instability, mechanical impingement, rotator cuff tendinopathy, and scapular dyskinesis. PURPOSE: To quantify and compare glenohumeral (GH) laxity between the throwing and non-throwing shoulder in professional baseball pitchers. METHODS: Force-displacement measures were performed bilaterally in 33 asymptomatic professional baseball pitchers. Shoulders were positioned at 90° of abduction and 60° of external rotation and a 10-daN (100- N) anterior- and posterior-directed force was applied to the humerus. An ultrasound scanner with transducer was used to dynamically track GH motion during joint loading. Static images were captured at baseline (0-daN) and 10-daN force levels. Using selected bony landmarks measurements of bony position were taken directly from the images and the difference in humeral head displacement was recorded in mm. RESULTS: ANOVA revealed no significant differences (p = .14) in laxity between the throwing (global 7.25mm, anterior 2.39mm, posterior 4.87mm) and non-throwing shoulders (global 7.35mm, anterior 2.45mm, posterior 4.91mm). Posterior translation (4.89mm) was found to be significantly greater (p < .01) than anterior translation (2.39mm). CONCLUSION: We conclude that no significant difference in laxity (anterior, posterior or global) exists between throwing and non-throwing shoulders in professional baseball pitchers, however posterior translation was found to be significantly greater than anterior translation in both shoulders of professional baseball pitchers.Figure: No Caption available.

Laxity, instability, and functional outcome after ACL injury: copers versus noncopers.

The purpose of this study was to determine the relationship among laxity, quadriceps strength, instability, and function in subjects with complete rupture of the anterior cruciate ligament (ACL) who compensate well for the injury (copers) and those who require surgical stabilization (noncopers). Forty-five patients with unilateral ACL rupture (confirmed via arthroscopy or magnetic resonance imaging (MRI) and arthrometer measurements) participated in this study. Subjects were divided into two groups: copers (N = 12), and subacute noncopers (N = 18) and chronic noncopers (N = 15). All copers had returned to all preinjury activity (including index sport) without limitation. Maximum manual anterior tibiofemoral laxity measurements, quadriceps femoris muscle strength measurements, and a series of hop tests were performed. Lysholm Scale, Knee Outcome Survey (KOS), global rating of knee function, and the International Knee Documentation Committee (IKDC) form were completed. There was no significant difference in laxity between copers (X = 5.5+/-2.7 mm) and noncopers (chronic, X = 5.1+/-2.8 mm and subacute, X = 4.2+/-2.2 mm) or in IKDC scores among the groups. The copers, however, scored significantly better than the chronic and subacute ACL-deficient subsets on all other measures. Measurements of laxity were not correlated to any functional outcome measure or to episodes of instability. Copers were not different in any meaningful way from the noncopers before injury, had equal or greater side-to-side laxity differences, and functioned normally. A battery of tests was identified that accurately discriminated noncopers from copers even early after injury. Thus, measurements of laxity alone are insufficient for determining functional status after ACL injury.

Effects of postoperative immobilization on the reconstructed anterior cruciate ligament. An experimental study in rabbits.

To investigate the effects of postoperative immobilization and limited motion on reconstructed anterior cruciate ligaments, 28 rabbits received an anterior cruciate ligament reconstruction using autogenous Achilles tendon and were then divided into three groups: fully immobilized, 4 weeks immobilized, and limited motion. Two rabbits from each group were evaluated macroscopically, histologically and microangiographically at 4-week intervals until 12 weeks postoperatively. An additional six rabbits in the 4 weeks immobilized and limited motion groups were studied biomechanically at 12 weeks postoperatively. Macroscopically, both immobilized groups showed more proliferation of the infrapatellar fat pad, which was adherent to the reconstructed anterior cruciate ligament. Histology revealed more rapid regeneration of reconstructed anterior cruciate ligaments in the limited motion group, with no findings of necrosis in the mid-substance. Microangiography indicated faster normalization of vascularity in the limited motion group. The biomechanical study showed no significant difference in laxity between the 4 weeks immobilized and limited motion groups. The graft stiffness and maximum load to failure were greater for the limited motion group, although the increase was not statistically significant. The histologic and microangiographic results from the limited number of animals in this study support limited postoperative motion in the anterior cruciate ligament reconstructed knee. However, there were no differences in terms of the biomechanical parameters at 12 weeks postoperatively between the immobilized and limited motion treatment modes.