Kinematics of ACL and anterolateral ligament. Part I: Combined lesion

PURPOSE

To quantify the influence of ALL lesions on static and dynamic laxity in ACL-deficient knee.

METHODS

The study was performed in 10 fresh-frozen knees. The joints were analysed in the following conditions: intact, ACL resection and ACL + ALL resection. Testing parameters were defined as: anterior displacement at 30° and 90° of flexion (AP30, AP90) applying a manual-maximum load; internal rotation at 30° and 90° of flexion (INT30, INT90) applying a 5 N m torque and internal rotation and acceleration during manual pivot-shift (PS) test. Kinematics was acquired by a navigation system; a testing rig and a torquemeter were used to control the limb position and the applied torque. Paired Student's t test was conducted to assess statistical difference, and significance was set at P < 0.05.

RESULTS

The ALL resection determined a significant increase in terms of internal rotation (INT30 P = 0.02, INT90 P = 0.03), while AP30 (P n.s) and AP90 (P n.s) were not affected. ALL resection produced a significant increase in terms of acceleration during PS test (P < 0.01), but no significant change in PS internal rotation was observed.

CONCLUSION

The ALL plays a significant role in controlling static internal rotation and acceleration during PS test. On the other hand, ALL resection did not produce any significant change in terms of anterior displacement. A trend was seen for the internal rotation during the pivot-shift test to increase after ALL resection was higher when compared to the intact and isolated ACL lesion states; however, the differences were not significant. The results highlight the clinical relevance of this structure that should be assessed before an ACL reconstruction in order to avoid residual laxity.

Polyurethane-based cell-free scaffold for the treatment of painful partial meniscus loss

PURPOSE

The aim of this study was to document, at mid-term follow-up, the clinical and MRI outcome of a polyurethane-based cell-free scaffold implanted to treat painful partial meniscus loss.

METHODS

Eighteen consecutive patients were enrolled and treated with arthroscopic polyurethane meniscal scaffold implantation and, in case of other comorbidities, with concurrent surgical procedures: 16 patients (9 men and 7 women, mean age 45 ± 13 years, mean BMI 25 ± 3, 12 medial and 4 lateral implants) were prospectively evaluated with the subjective and objective IKDC and the Tegner scores at 24, 36, 48, 60, and 72 months of follow-up. Eleven patients were also evaluated by 1.5-T MRI at the final follow-up.

RESULTS

The IKDC subjective score showed a significant improvement from baseline to 24 months (45.6 ± 17.5 and 75.3 ± 14.8, respectively; p = 0.02) and subsequent stable results over time for up to 72 months (final score 75.0 ± 16.8). The Tegner score improvement between pre-operative status and final follow-up was also significant (p = 0.039). Nevertheless, the final score remained significantly lower than the pre-injury sports activity level (p = 0.027). High-resolution MRIs documented the presence of abnormal findings in terms of morphology, signal intensity, and interface between the implant and the native meniscus. Implant extrusion and bone oedema at the treated compartment were also observed in most of the cases, even though no correlation was found between imaging findings and clinical outcome.

CONCLUSIONS

The present study reports satisfactory clinical outcomes at mid-term follow-up after polyurethane-based meniscal cell-free scaffold implantation. The treatment was effective both in cases of isolated partial meniscal lesions and in complex cases requiring the combination with other surgical procedures. On the other hand, a high rate of altered MRI aspects was documented. However, no correlation was found between the altered imaging parameters and the overall positive clinical findings, thus supporting the use of this procedure to treat painful partial meniscus loss.

LEVEL OF EVIDENCE

Case series, Level IV.

Total knee replacement: intraoperative and postoperative kinematic assessment

BACKGROUND AND AIM

The main goals of the total knee arthroplasty (TKA) is to reduce the perceived pain and  restore knee mobility and function in case of osteoarthritic knees joints. Literature shows how the three major causes of TKA failures are related to wear, loosening and instability and this is due to a problem of imbalance and malalignment. Intraoperative and postoperative kinematics analysis could be of benefit for improving surgery outcome. The aim of the present paper is to give an overview of the two set-up with the highest accuracy for intraoperative and postoperative TKA kinematics evaluation, currently in use at Istituto Ortopedico Rizzoli. Introperative and Postoperative Evaluation: For intraoperative evaluation it has been presented a navigation system with a specifically developed software, while for the postoperative it has been presented the roentgen stereophotogrammetric analysis (RSA). The navigation system consists in a laptop connected with an optoelectronic localizer (Polaris, Northern Digital Inc, Canada).  Two reference arrays with passive optical markers and a marked probe are used to localize the knee joint in the 3D space and track the joint kinematics. The RSA is a radiographic technique used in orthopaedic field for measuring micromotion at bone/prosthesis interface or for joint kinematics evaluation. The RSA uses two X-ray sources synchronized with two digital flat-panels.

CONCLUSIONS

The present paper shows that using the navigation system allows the surgeon to easily perform kinematic and alignment evaluation during TKA surgery while the RSA allows a quantitative evaluation of the joint kinematics during the recovery time.

ACL rupture and joint laxity progression: a quantitative in vivo analysis

PURPOSE

Benefits of an early reconstruction and the optimal time lapse between injury and surgery to reduce the effects of altered kinematics in ACL-deficient knees are still controversial.

AIM

The aim of this study was to clarify, through a quantitative in vivo evaluation, the effects of the time lapse between ACL injury and surgery in terms of changes in the pre-operative knee laxity.

METHODS

An in vivo study was performed on 99 patients who underwent ACL surgery. Just before the graft fixation, six laxity tests were performed for all the subjects at manual-maximum load: anterior-posterior displacement and internal-external rotation at 30° and 90° of knee flexion (AP30, AP90, IE30, IE90) as well as varus-valgus rotation (VV0, VV30) at 0° and 30° of flexion. Kinematics data were acquired by a navigation system. The Spearman rank correlation was used to assess correlation between rank and continuous data. Significance was set at P = 0.05.

RESULTS

The analysis highlighted a significant influence of the injury-to-surgery time lapse on VV0 and AP90 compared with pre-operative laxity levels. Meniscus status also significantly affected the pre-operative laxity in the VV0 (Spearman's ρ = 0.203, P = 0.038; GLM with meniscal correction partial η = 0.27, P = 0.007) and AP90 (Spearman's ρ = 0.329, P = 0.001; GLM with meniscal correction partial η = 0.318, P = 0.017) tests.

CONCLUSION

The main finding of this study is that patients with ACL rupture and a higher injury-to-surgery time present higher values of knee laxity involving AP90 displacement and VV30 rotation. Clinical relevance of the study is that ACL-deficient joint laxity, involving anterior-posterior displacement at 90° of knee flexion and varus-valgus rotation at 0° of flexion, is significantly affected by the lapse of injury-to-surgery time. This highlights the importance of considering the effects of delaying surgery when managing patients with such deficiency.

Technical variables of ACL surgical reconstruction: effect on post-operative static laxity and clinical implication

PURPOSE

The hypothesis was that an alteration of different surgical variables of ACL reconstruction would produce significant changes in post-operative static laxity of knee joint.

METHODS

Joint laxity was acquired by a surgical navigation system for 17 patients just after graft fixation during single-bundle reconstruction with extra-articular lateral tenodesis. The analysed laxity parameters were: internal/external rotation at 30° (IE30) and 90° (IE90) of flexion, varus/valgus rotation at 0° (VV0) and 30° (VV30) of flexion and anterior/posterior displacement at 30° (AP30) and 90° (AP90) of flexion. As surgical variables, the angles between the tibial tunnel and the three planes were defined as well as the lengths of the tunnel and the relationship between native footprints and tunnels. The same analysis was performed for the femoral side. All surgical variables were combined in a multivariate analysis to assess for predictive factors between them and post-operative laxities values. To quantify the performance of each multivariate model, the correlation ratio (η ²) and the corresponding P value (*P < 0.050) have been evaluated.

RESULTS

Multivariate analysis underlined statistically significant models for the estimation of: AP30 (η ² = 0.987; P = 0.014), IE30 (η ² = 0.995; P = 0.005), IE90 (η ² = 0.568; P = 0.010), VV0 (η ² = 0.932; P = 0.003). The parameters that greatly affected the identified models were the orientation of the tibial tunnel with respect to the three anatomical planes. The estimation of AP30, IE30 and IE90 got lower value as the orientation of the tibial tunnel with respect to transverse plane decreases. Considering the orientation to sagittal ([Formula: see text]) and coronal ([Formula: see text]) plane, we found that their reduction provoked a decrease in the estimation of AP30, IE30 and IE90 (except [Formula: see text] that did not appear in the estimation of AP30). The estimation of VV0 got an increase of [Formula: see text], and [Formula: see text] which led to a laxity reduction.

CONCLUSION

The main finding of the present in vivo study was the possibility to determine significant effects on post-operative static laxity level of different surgical variables of ACL reconstruction. In particular, the present study defined the conditions that minimize the different aspects of post-operative laxity at time-zero after surgery.

Does meniscus removal affect ACL-deficient knee laxity? An in vivo study

PURPOSE

The purpose of the present study was to determine, in vivo, the effect of different types of meniscectomy on an ACL-deficient knee.

METHODS

Using a computer-assisted navigation system, 56 consecutive patients (45 men and 11 women) were subjected to a biomechanical testing with Lachman test (AP30), drawer test (AP90), internal/external rotation test, varus/valgus rotation test and pivot-shift test. The patients were divided into three groups according to the status of the medial meniscus. Group BH, 8 patients with bucket-handle tear of medial meniscus underwent a subtotal meniscectomy; Group PHB, 19 patients with posterior horn body of medial meniscus tear underwent a partial meniscectomy; and Group CG with isolated ACL rupture, as a control group, with 29 patients.

RESULTS

A significant difference in anterior tibial translation was seen at 30 grades and in 90 grades between BH and PHB groups compared to the CG. In response to pivot-shift test, no significant differences in terms of AREA and POSTERIOR ACC were found among the three groups (n.s). Concerning the anterior displacement of the pivot shift a statistically significant differences among the three tested groups was found.

CONCLUSION

The present study shows that meniscal defects significantly affect the kinematics of an ACL-deficient knee in terms of anterior tibial translation under static and dynamic testing.

Predictive mathematical modeling of knee static laxity after ACL reconstruction: in vivo analysis

Previous studies did not take into consideration such large variety of surgery variables which describe the performed anterior cruciate ligament (ACL) reconstruction and the interaction among them in the definition of postoperative outcome. Seventeen patients who underwent navigated Single Bundle plus Lateral Plasty ACL reconstruction were enrolled in the study. Static laxity was evaluated as the value of anterior/posterior displacement at 30° and at 90° of flexion, internal/external rotation at 30° and 90° of knee flexion, varus/valgus test at 0° and 30° of flexion. The evaluated surgical variables were analyzed through a multivariate analysis defining the following models: AP30estimate, AP90estimate, IE30estimate, IE90estimate, VV0estimate, VV30estimate. Surgical variables has been defined as the angles between the tibial tunnel and the three planes, the lengths of the tunnel and the relationship between native footprints and tunnels. An analogous characterization was performed for the femoral side. Performance and significance of the defined models have been quantified by the correlation ratio (η(2)) and the corresponding p-value (*p < 0.050). The analyzed models resulted to be statistically significant (p < 0.05) for prediction of postoperative static laxity values. The only exception was the AP90estimate model. The η(2) ranged from 0.568 (IE90estimate) to 0.995 (IE30estimate). The orientation of the tibial tunnel resulted to be the most important surgical variable for the performed laxity estimation. Mathematical models for postoperative knee laxity is a useful tool to evaluate the effects of different surgical variables on the postoperative outcome.

DOES TOTAL KNEE REPLACEMENT MODIFY FLEXION AXIS OF THE KNEE ON FRONTAL AND AXIAL PLANE REGARDLESS FROM LIMB ALIGNMENT?

The optimal reference for rotational positioning of femoral component in total knee replacement (TKR) is debated. Navigation has been suggested for intra-op acquisition of patient’s specific kinematics and functional flexion axis (FFA). The main purpose of the present study is to prospectively investigate whether pre-operative FFA in patients with osteoarthritis (OA) and varus alignment changes after TKR and whether a correlation exists between post-op FFA and pre-op alignment. A navigated TKR was performed in 108 patients using a specific software to acquire passive joint kinematics before and after TKR. The knee was cycled through three passive range of motions (PROM), from 0° to 120°. FFA was computed using the mean helical axis algorithm. The angle between FFA and surgical TEA was determined on frontal (αf) and axial (αa) plane. The pre- and post-op hip-knee-ankle angle (HKA) was determined. Post-op FFA was different from pre-op FFA only on frontal plane. No significant difference was found on axial plane. No correlation was found between HKA-pre and αA-pre. A significant correlation was found between HKA-pre and αF–pre. The study concluded that TKR modifies FFA only on frontal plane. No difference was found on axial plane. Pre-op FFA is in a more varus position respect to TEA. The position of FFA on frontal plane is dependent on limb alignment. The present study has demonstrated TKR modifies the position of FFA only on frontal plane. The position of FFA on axial plane is not dependent on the amount of varus deformity and is not influenced by TKR. Level of evidence, IV, case series.

The adductor tubercle as an important landmark to determine the joint line level in total knee arthroplasty: from radiographs to surgical theatre

PURPOSE

The restoration of the normal joint line (JL) is important both in primary and revision total knee arthroplasty (TKA). However, the assessment of the femoro-tibial JL is still controversial. A strong correlation between femoral width (FW) and distance from adductor tubercle (AT) to JL was found on radiographs, with a ratio of 0.54. The hypothesis was that this ratio was applicable also in the surgical theatre by using measurements obtained intra-operatively with a caliper.

METHODS

Femoral width, AT to JL distance and the RATIO between AT to JL distance and FW of 40 patients who underwent TKA were measured on radiograph and intra-operatively. Bland-Altman agreement tests with repeated measurements and linear regression analysis were used. The ratio was used to estimate the distance between JL and AT.

RESULTS

The AT to JL distance/FW ratio calculated with linear regression resulted 0.54 for radiographic measurements and 0.53 for intra-operative measurements. There was no difference (0.009 ± 0.03) between the calculated ratios on radiographic and intra-operative measurements, and the correlation between intra-operative and radiographic measurements was 0.5 (p = 0.0016).

CONCLUSIONS

This study shows that the validity of the radiographic method which uses an AT to JL distance/FW ratio to determine the level of the JL is confirmed also when using intra-operatively acquired measurements. Thus, this ratio represents a reliable tool to determine the JL level even in challenging prosthetic revision cases when the anatomical JL is missing.

LEVEL OF EVIDENCE

Case series, Level IV.

Return to sport after anterior cruciate ligament reconstruction in professional soccer players

BACKGROUND

To investigate time to return to sport and rate of professional sport activity in a homogenous group of competitive soccer players 4 years after anterior cruciate ligament (ACL) reconstruction and rehabilitation.

METHODS

Twenty-one male professional soccer players (mean age 22.9±5.4 years) underwent non-anatomical double-bundle autologous hamstring ACL reconstruction and followed the same rehabilitative protocol. Clinical evaluation was performed preoperatively and at 3, 6 and 12-month follow-up. Data regarding return to train and official match, sport activity, complications and revision surgeries were collected at 4-year follow-up.

RESULTS

Laxity test (KT-2000) and total KOOS mean score resulted in a significant improvement from the preoperative status to the 12-month follow-up (p<0.0001). The KOOS mean value showed a significant progressive improvement from the preoperative status to 6-month follow-up (p=0.0010) as well, while values collected at 6 and 12-month follow-up were comparable (p=0.2349). Returned to official matches 186±53 days after surgery. After 12 months, 95% came back to the same activity level performed before injury. Four years after ACL reconstruction, 15 patients (71%) were still playing competitive soccer. One patient (5%) underwent ACL failure and subsequent revision.

CONCLUSIONS

The ACL reconstruction with the presented technique followed by patient-tailored rehabilitation, allowed 95% and 62% professional male soccer players to return to the same sport activity 1 year and 4 years after surgery respectively. However, 71% were still able to play competitive soccer at final follow-up. Clinical scores were restored after 6 months.

LEVEL OF EVIDENCE

IV, case series.

Polyurethane scaffold in lateral meniscus segmental defects: clinical outcomes at 24 months follow-up

BACKGROUND

Segmental tissue loss in the lateral meniscus is associated with pain and increased risk of osteoarthritis even when indications have been carefully considered.

HYPOTHESIS

Repairing the defect using a novel biodegradable scaffold will reduce pain and restore the knee function.

METHODS

In this prospective multicenter study, a total of 54 patients (37 males/17 females; mean age: 28 years [16-50]) were enrolled. All patients presented with postmeniscectomy syndrome and segmental lateral meniscus loss, and were treated with a polyurethane biodegradable scaffold (Actifit(®), Orteq) implanted arthroscopically. Clinical outcomes were assessed at 6, 12 and 24 months using Visual Analogue Scale (VAS), International Knee Documentation Committee Score (IKDC) and Knee Injury and Osteoarthritis Outcome Score (KOOS).

RESULTS

VAS decreased from 5.5 at baseline to 3.6 at 6 months, 3.4 at 12 months and 2.9 at 24 months. IKDC improved from 47.0 at baseline to 60.2, 67.0 and 67.0 at 6, 12 and 24 months. All KOOS subscores improved between baseline and 24 months.

DISCUSSION

Clinical results of this study demonstrate clinically and statistically significant improvements of pain and function scores (VAS, IKDC, and all KOOS subscales except sport), at the 6 months follow-up and on all clinical outcomes at the 2-year follow-up. The Actifit(®) scaffold is safe and effective in treating lateral meniscus defects.

LEVEL OF EVIDENCE IV

continuous prospective multicenter study.

Osteochondral scaffold reconstruction for complex knee lesions: a comparative evaluation

BACKGROUND

The primary aim of the present study is to evaluate the results obtained in challenging knee lesions with the implant of an osteochondral scaffold and concomitant treatment of all comorbidities. The secondary aim is to compare the results obtained with those found when a chondral scaffold was applied.

MATERIALS AND METHODS

Patients affected by complex lesions of the knee articular surface were included. "Complex cases" were defined according to the following criteria: previous clinical history of intra-articular fracture, lesion located at the tibial plateau, concurrent knee axial realignment procedure, concurrent meniscal scaffold or allograft implantation, and multiple articular surface lesions treated. Thirty-three patients were treated with the implantation of an osteochondral scaffold. The results of a homogeneous group of 23 patients previously treated and prospectively evaluated after implantation of a chondral scaffold were analyzed and compared.

RESULTS

IKDC subjective score improved significantly from pre-operative (40.4±14.1) to 12months' follow-up (69.6±17.0; p<0.0005) with a further improvement at the final evaluation at 24months (75.5±15.0; p=0.038). The same positive trend was confirmed by the VAS and Tegner scores. At final follow-up the group treated with the osteochondral scaffold presented a better subjective IKDC score with respect to the group treated with the chondral scaffold (p=0.034).

CONCLUSIONS

A regenerative procedure to address the entire osteochondral unit, together with the treatment of all comorbidities, might offer good results also in complex cases otherwise doomed to non-biological resurfacing.

LEVEL OF EVIDENCE III

Comparative study.

Unicompartmental osteoarthritis: an integrated biomechanical and biological approach as alternative to metal resurfacing

PURPOSE

Although traditionally not indicated for the treatment of osteoarthritis (OA), regenerative procedures are becoming a focus of increased interest due to their potential to provide pain relief and alter the progression of degenerative diseases. The purpose of this study was to assess whether a combined biomechanical and biological approach could offer good results in unicompartmental OA, thus delaying the need for unicompartmental arthroplasty in patients too young or refusing metal resurfacing.

METHODS

Forty-three patients (mean age = 40.1 ± 11 years, 33 men and 10 women, mean BMI = 25 ± 3) affected by unicompartmental OA (Kellegren-Lawrence score = 3) in stable joints were enrolled and treated consecutively. Fifteen patients were treated with osteotomy and osteochondral biomimetic scaffold implant (3 of them also with meniscal substitution), 11 with osteotomy and meniscal scaffold implant, 9 with osteotomy and meniscal allograft implant, and 8 with both cartilage and meniscal reconstruction, depending on the specific joint compartment main requirements. Clinical evaluation was performed at 3-year (2-4) median follow-up using the following scoring systems: IKDC subjective and objective, VAS for pain, and Tegner scores. Failures, adverse events, and complications were also reported.

RESULTS

The IKDC subjective score improved from 47.3 to 79.6 at the final evaluation (p < 0.0005), VAS improved from 6.1 to 2.3 (p < 0.0005), and also sport activity level evaluated with the Tegner score showed a significant improvement, from 2 (1-5) to 4 (3-10; p < 0.0005), even if without achieving the pre-injury level (6, p = 0.001). A further subanalysis confirmed the positive outcome obtained in all the treatment subgroups and showed a higher clinical improvement in patients under the age of 40 years (IKDC subjective 84.4 ± 13.2 vs 76.5 ± 17.3; p = 0.03).

CONCLUSION

This integrated biological and biomechanical approach produced a marked improvement at short-medium follow-up in patients affected by unicompartmental OA. Even though a good outcome was achieved at all ages, patients under the age of 40 years presented a greater clinical and subjective improvement. Longer follow-up studies are needed to show results over time and confirm this approach as an effective alternative to unicompartmental implants.

Do pre-operative knee laxity values influence post-operative ones after anterior cruciate ligament reconstruction?

The objective of this study was to verify whether pre-reconstruction laxity condition effects post-reconstruction outcome. A total of 100 patients who underwent navigated Anterior Cruciate Ligament (ACL) reconstruction were included in the study and knee laxity analysed retrospectively. The knee was assessed in six different laxity tests before and after ACL reconstruction, namely antero-posterior (AP) and internal-external (IE) at 30° and 90°, and varus-valgus (VV) rotations at 0° and 30° of flexion. For each test, the least square (LS) fitting line based on pre-operative-to-post-operative laxity value was calculated. To what degree the post-operative laxity value is explainable by the corresponding pre-operative condition was evaluated by the LS line slope. Post-operatively, for each single patient, the grade of laxity decreased at any evaluated test. The strongest influence of pre-operative-to-post-operative laxity values was found during IE30 and IE90 tests. While AP30 and VV0 tests seem to be those in which the post-reconstruction laxity was barely affected by the pre-surgery condition. The analysis of the global laxity reduction confirms the previous results. Following this hypothesis, our study remarks on the importance of combined lesions to secondary restraints and the importance of fully understanding the residual laxity to optimize the surgical technique.

Conservative treatment of spontaneous osteonecrosis of the knee in the early stage: pulsed electromagnetic fields therapy

BACKGROUND

HYPOTHESIS

pulsed electromagnetic fields treatment might improve symptoms in the early stage of spontaneous osteonecrosis of the knee.

METHODS

Twenty-eight patients (19M/9F, age 49.8±16.4 years) suffering from symptomatic (pain) Koshino stage I spontaneous osteonecrosis of the knee, confirmed by magnetic resonance imaging (MRI) were treated with local pulsed electromagnetic fields therapy (6 h daily for 90 days). Clinical evaluation: baseline, 6- and 24-month follow-up by VAS for pain, knee society score (KSS), Tegner and EQ-5D scales. MRI evaluation: baseline and 6-month follow-up, measuring bone marrow lesion's areas and grading these lesions by WORMS score. Failures: patients undergoing knee arthroplasty.

RESULTS

Pain significantly reduced at 6 months (from 73.2±20.7 to 29.6±21.3, p<0.0001), which remained almost unchanged at final follow-up (27.0±25.1). KSS significantly increased in first 6 months (from 34.0±13.3 to 76.1±15.9, p<0.0001) and was slightly reduced at final follow-up (72.5±13.5, p=0.0044). Tegner median level increased from baseline to 6-month follow-up (1(1-1) and 3(3-4), respectively, p<0.0001) and remained stable. EQ-5D improved significantly throughout the 24 months (0.32±0.33, baseline; 0.74±0.23, 6-month follow-up (p<0.0001); 0.86±0.15, 24-month follow-up (p=0.0071)). MRI evaluation: significant reduction of total WORMS mean score (p<0.0001) and mean femoral bone marrow lesion's area (p<0.05). This area reduction was present in 85% and was correlated to WORMS grading both for femur, tibia and total joint (p<0.05). Four failures (14.3%) at 24-month follow-up.

CONCLUSIONS

Pulsed electromagnetic fields stimulation significantly reduced knee pain and necrosis area in Koshino stage I spontaneous osteonecrosis of the knee already in the first 6 months, preserving 86% of knees from prosthetic surgery at 24-month follow-up. No correlation was found between MRI and clinical scores.

LEVEL OF EVIDENCE

Level IV; case series.

Current concept in rotational laxity control and evaluation in ACL reconstruction

Rotation combined with translation; compose the three-dimensional motion of the knee subluxation in anterior cruciate ligament deficient knee. The worldwide scientists were focused initially on the translation part of this complex 3D motion, but since the beginning of the century there was a large interest on knee rotational laxity study. Lot of paper reported new devices and results with an explosion since the beginning of the decade. The purpose of this review is to provide an extensive critical analysis of the literature and clarify the knowledge on this topic. We will start with a dismemberment of different rotational laxities reported: the rotation coupled with translation in 2D tests such as Lachman test and anterior drawer test; the rotational envelope considering the maximum internal external rotation; and the "active rotation" occurring in 3D Pivot-shift (PS) test. Then we will analyze the knee kinematics and the role of different anterior cruciate ligament (ACL) bundle on rotation. A review of different mechanical and radiological devices used to assess the different rotations on ACL deficient knees will be presented. Two groups will be analyzed, dynamic and static conditions of tests. Navigation will be described precisely; it was the starter of this recent interest in rotation studies. Opto electronic and electromagnetic navigation systems will be presented and analyzed. We will conclude with the last generation of rotational laxity assessment devices, using accelerometers, which are very promising.

Surgical treatment for early osteoarthritis. Part II: allografts and concurrent procedures

Young patients with early osteoarthritis (OA) represent a challenging population due to a combination of high functional demands and limited treatment options. Conservative measures such as injection and physical therapy can provide short-term pain relief but are only palliative in nature. Joint replacement, a successful procedure in the older population, is controversial in younger patients, who are less satisfied and experience higher failure rates. Therefore, while traditionally not indicated for the treatment of OA, cartilage repair has become a focus of increased interest due to its potential to provide pain relief and alter the progression of degenerative disease, with the hope of delaying or obviating the need for joint replacement. The field of cartilage repair is seeing the rapid development of new technologies that promise greater ease of application, less demanding rehabilitation and better outcomes. Concurrent procedures such as meniscal transplantation and osteotomy, however, remain of crucial importance to provide a normalized biomechanical environment for these new technologies.

LEVEL OF EVIDENCE

Systematic review, Level II.

Surgical treatment for early osteoarthritis. Part I: cartilage repair procedures

Young patients with early osteoarthritis (OA) represent a challenging population due to a combination of high functional demands and limited treatment options. Conservative measures such as injection and physical therapy can provide short-term pain relief but are only palliative in nature. Joint replacement, a successful procedure in the older population, is controversial in younger patients, who are less satisfied and experience higher failure rates. Therefore, while traditionally not indicated for the treatment of OA, cartilage repair has become a focus of increased interest due to its potential to provide pain relief and alter the progression of degenerative disease, with the hope of delaying or obviating the need for joint replacement. This review of cartilage repair techniques will discuss currently available procedures, specifically pertaining to experiences in the setting of early OA. Level of evidence IV.

Does chronic medial collateral ligament laxity influence the outcome of anterior cruciate ligament reconstruction?: a prospective evaluation with a minimum three-year follow-up

We have shown in a previous study that patients with combined lesions of the anterior cruciate (ACL) and medial collateral ligaments (MCL) had similar anteroposterior (AP) but greater valgus laxity at 30° after reconstruction of the ACL when compared with patients who had undergone reconstruction of an isolated ACL injury. The present study investigated the same cohort of patients after a minimum of three years to evaluate whether the residual valgus laxity led to a poorer clinical outcome. Each patient had undergone an arthroscopic double-bundle ACL reconstruction using a semitendinosus-gracilis graft. In the combined ACL/MCL injury group, the grade II medial collateral ligament injury was not treated. At follow-up, AP laxity was measured using a KT-2000 arthrometer, while valgus laxity was evaluated with Telos valgus stress radiographs and compared with the uninjured knee. We evaluated clinical outcome scores, muscle girth and time to return to activities for the two groups. Valgus stress radiographs showed statistically significant greater mean medial joint opening in the reconstructed compared with the uninjured knees (1.7 mm (SD 0.9) versus 0.9 mm (SD 0.7), respectively, p = 0.013), while no statistically significant difference was found between the AP laxity and the other clinical parameters. Our results show that the residual valgus laxity does not affect AP laxity significantly at a minimum follow up of three years, suggesting that no additional surgical procedure is needed for the medial collateral ligament in combined lesions.

Novel nanostructured scaffold for osteochondral regeneration: pilot study in horses

The present in vivo preliminary experiment is aimed at testing mechanical and biological behaviour of a new nano-structured composite multilayer biomimetic scaffold for the treatment of chondral and osteochondral defects. The three-dimensional biomimetic scaffold (Fin-Ceramica Faenza S.p.A., Faenza-Italy) was obtained by nucleating collagen fibrils with hydroxyapatite nanoparticles, in two configurations, bi- and tri-layered, to reproduce, respectively, chondral and osteochondral anatomy. Chondral defects (lateral condyle) and deep osteochondral defects (medial condyle) were made in the distal epiphysis of the third metacarpal bone of both forelimbs of two adult horses and treated respectively with the chondral and osteochondral grafts. Both animals were euthanised six months follow up. The images obtained at the second look arthroscopy evaluation, performed two months after surgery, demonstrated good filling of the chondral and osteo-chondral defects without any inflammatory reaction around and inside the lesions. At the histological analysis the growth of trabecular bone in the osteochondral lesion was evident. Only in one case, the whole thickness of the osteochondral lesion was filled by fibrocartilaginous tissue. The formation of a tidemark line was evident at the interface with the newly formed bone. Newly formed fibrocartilaginous tissue was present in the area of the chondral defect. Initial alignment of the collagen fibres was recognisable with polarised light in both groups. The results of the present pilot study showed that this novel osteochondral and chondral scaffold may act as a suitable matrix to facilitate orderly regeneration of bone and hyaline-like cartilage.