Minimally invasive anatomic reconstruction of the anterolateral ligament with ipsilateral gracilis tendon: a kinematic in-vitro study.

PURPOSE: The anterolateral ligament (ALL) has been defined as a key stabilizer of internal tibial rotation at 35° or more of knee flexion, with a minimal primary or secondary stabilizing role in the AP direction. This study aimed to demonstrate that anatomical reconstruction of the ALL confers rotational stability equal to that of the uninjured knee. HYPOTHESIS: anteroposterior (AP) and rotatory laxity will significantly vary after ALL tenotomy and ALL reconstruction with the author's previously described technique. METHODS: After ultrasound (US) ALL identification, different kinematic measurements were performed with an image-less Computer-Assisted Navigation System with dedicated software for Laxity Analysis in 5 knee specimens. Anteroposterior (AP) translations and varus/valgus (VV) and Internal-External (IE) rotations were evaluated by two trained orthopedic surgeons before ALL section, after ALL section, and after ALL anatomical reconstruction with doubled ipsilateral autologous gracilis tendon. RESULTS: ALL resection significantly increased laxity in IE rotations with knee 90° flexed (IE90) and AP translation with tibia internally rotated and the knee 30° flexed (APlat) (p < 0.05). ALL reconstruction significantly reduced laxity in IE90 and APlat (p < 0.05) and reduced VV rotations at 30° of flexion (VV30) (p < 0.05). There were no statistically significant elongation differences between native ALL and reconstructed ALL (graft) during laxity tests. The inter-operator repeatability of the tests was excellent for each measurement. CONCLUSIONS: ALL acted as an important internal tibial rotation restrain at 90° and a significant (secondary) AP stabilizer at 30° of knee flexion. The presented ALL reconstruction technique significantly restored the increase of knee laxity produced by the ALL section. SCIENTIFIC LEVEL: Case-Controlled Laboratory Study, Level III.

The sagittal geometry of the trochlear groove could be described as a circle: an intraoperative assessment with navigation.

PURPOSE: The aim of this study was to describe the sagittal geometry of the trochlear groove in patients who underwent primary TKA, based on intraoperative data acquired with a navigation system. METHODS: Intraoperative navigation data were collected from 110 patients. All operations were guided by a non-image-based navigation system (BLU-IGS, Orthokey Italia Srl). The trochlear groove has been described on the three anatomical planes; in particular, on the sagittal plane the hypothesis has been verified that the acquired points are referable to a circle. Using the data collected during intraoperative navigation, possible correlation between the radius of the trochlear groove and other femur dimension (length, AP dimension) was analyzed; the orientation of the trochlear sulcus with respect to the mechanical axis and the posterior condyle axis was analyzed too, searching for possible correlation between groove alignment (frontal and axial) or groove radius and the hip-knee-ankle (HKA). RESULTS: The average radius of curvature of the femoral trochlea was 25.5 ± 5.6 mm; the difference was not statistically significant between the men and women (n.s. p value). No correlation was found between the trochlear groove radius and the femur length (r = - 0.02) or the HKA-phenotypes (r = 0.03) and between the groove alignment and HKA-phenotypes. On axial plane, the trochlear groove was 3.2° ± 4.3° externally rotated, with respect to the posterior condylar axis; on frontal plane, the trochlear groove was 3.9° ± 5.3° externally rotated, with respect to the mechanical axis. In both cases, no statistically significant differences were found between male and female and between left and right limb (p > 0.05). CONCLUSION: The present study shows that the sagittal plane geometry of the femoral trochlea in patients affected by osteoarthritis could be described accurately as a circle. The acquisition of the trochlear morphology intraoperatively can lead to more anatomically shape definition, to investigate deeper its radius of curvature and geometry. Trochlear shape could be used as landmarks for femoral component positioning, thus customizing the implant design, optimize the outcomes and improving anterior knee pain after TKA. LEVEL OF EVIDENCE: IV.

The adductor tubercle: an important landmark to determine the joint line level in revision total knee arthroplasty.

PURPOSE: The restoration of the physiological femoro-tibial joint line (JL) is important to obtain a good outcome in revision total knee arthroplasty (RTKA). However, its assessment is challenging. The ratio of the distance between the adductor tubercle (AT) JL (ATJL) and the trans-epicondylar femoral width (FW) was proposed as a reliable method. The purpose of this study was to check whether this ratio is a reliable tool to restore the prosthetic JL height in challenging prosthetic revision cases. METHODS: Twenty-one patients (mean age 65.8 years) were recruited. During surgery, FW was measured and ATJL distance was calculated using 0.53 (SD 0.03) as the ratio. After implant positioning, the obtained ATJL line was measured to verify the accuracy of the surgical procedure. Thirteen patients presented a healthy contralateral knee: a comparative radiograph examination was performed to verify the appropriateness of the restored JL height. RESULTS: The intra-operatively calculated ATJL was not significantly different with respect to the measured ATJL obtained after prosthetic component implantation. The comparative analysis between the restored JL and the JL of the contralateral not operated knee was also not statistically significant, thus confirming the appropriateness of the restored JL height. CONCLUSIONS: This study shows that the method which uses an AT to JL distance/FW ratio to determine the JL level, previously applied in primary TKA, is valid when using intra-operatively acquired measurements in RTKA. This is clinically relevant since it represents a reliable tool which helps surgeons to restore the JL level in challenging prosthetic revision cases. LEVEL OF EVIDENCE: Case series, Level IV.

Good survivorship of all-polyethylene tibial component UKA at long-term follow-up.

PURPOSES: To determine the long-term survival rate of an all-polyethylene tibial unicompartmental knee arthroplasty (UKA) in a large series of consecutive patients and to investigate the possible factors that could influence the outcome. METHODS: A retrospective evaluation of 273 patients at 6-13 years of follow-up was performed. Clinical evaluation was based on KSS and WOMAC scores. Subjective evaluation was based on a visual analogue scale for pain self-assessment. Radiographic evaluation was performed to assess femoral-tibial angle (FTA), posterior tibial slope (PTS) and tibial plateau angle (TPA). A Kaplan-Meier survival analysis was performed assuming revision for any reason as primary endpoint. RESULTS: The 10-year implant survivorship was 87.6%. Twenty-five revisions (9.2%) were performed, and aseptic loosening of the tibial component was the most common failure mode (11 cases, 4%). The comparison of survival rate according to age at surgery did not show significant difference. Age at surgery, FTA, TPA and PTS were not related to higher risk of revision. No correlations were found between BMI, age at surgery and clinical scores. Finally, no statistical differences of radiographic measurements were found between revisions and non-revisions. CONCLUSIONS: The present study has demonstrated on a large series of patients that UKA with an all-polyethylene tibial component, with an accurate technique and a proper patient selection, can provide a satisfactory clinical and functional outcome and a good overall survivorship of the implant at long-term follow-up. These advantages could be achieved at a lower cost. LEVEL OF EVIDENCE: Retrospective Therapeutic Study, Level IV.

Does patellofemoral geometry in TKA affect patellar position in mid-flexion?

PURPOSE: This study aimed to compare the position of the patella at 90° of flexion before and after implantation of two TKA models with identical tibiofemoral geometry but different trochlear and patellar designs. The hypothesis was that the design with the deeper 'anatomic' trochlea could produce more natural patellar positions. METHODS: Intra-operative navigation data were collected from 22 consecutive cases that received two TKA designs (9 HLS Noetos(®) and 13 HLS KneeTec(®)). Both implants were cemented postero-stabilised TKAs with mobile tibial inserts and patellar resurfacing. Operations were guided by a non-image-based system that recorded relative femoral, tibial and patellar positions pre- and post-operatively. RESULTS: The two groups exhibited little difference in femoral internal-external rotation and anterior-posterior translation during knee flexion. The two groups exhibited significant differences in patellar position at 90° of flexion. Post-operatively, the patella was similarly shifted medially relative to the femur (Noetos 6.9 mm, KneeTec 6.0 mm, n.s.). Patellar flexion was equivalent in native knees (Noetos 18.3°, KneeTec 20.5°, n.s.), but in implanted knees, it was considerably different (Noetos 6.3°, KneeTec 23.5°, p = 0.031). CONCLUSIONS: The present study compared intra-operative navigation data from two patient series that received TKA implants with identical tibiofemoral articular geometry but different patellofemoral designs. The results confirm that tibiofemoral kinematics are unchanged, but that patellar positions at 90° of flexion offer greater mechanical advantage to the quadriceps using the KneeTec than using the Noetos. The findings raise awareness of influence of patellofemoral geometry on mid-flexion kinematics and help surgeons select the most suitable implant for patients with weak quadriceps muscles or with history of patellar instability. LEVEL OF EVIDENCE: Comparative study, Level III.

Deep-dished highly congruent tibial insert in CR-TKA does not prevent patellar tendon angle increase and patellar anterior translation.

PURPOSE: Starting from the hypothesis that a deep-dished highly congruent tibial insert in cruciate-retaining total knee arthroplasty would prevent the increase in patellar tendon angle and anterior patellar translation by reducing the paradoxical anterior femoral translation, the main purpose of the present study was to investigate the effect of this prosthesis design, and secondary to assess the clinical outcomes at 6-month follow-up. METHODS: Twenty patients treated with cruciate-retaining total knee arthroplasty with navigation technique were enrolled and prospectively followed up at 6 months. The median value of age was 71 years (57-83). Before and after surgery, the following parameters were calculated: patellar tendon angle, anterior-posterior and medio-lateral patellar translation, patellar height and range of motion. All patients were assessed with the SF-36 Physical Functioning and the Knee injury and Osteoarthritis Outcome Score ADL scores. RESULTS: Patellar tendon angle and anterior patellar translation significantly increased in post-operative conditions (p < 0.0001); a statistically significant medial patellar translation was found (p < 0.0001), while patellar height did not show any difference between pre- and post-operative conditions (n.s). A significant correlation was found between patellar tendon angle and anterior patellar translation and the clinical scores (p < 0.0417). There was a significant post-operative decrease (p < 0.0033) in the range of motion. CONCLUSIONS: The present study failed to demonstrate that deep-dished highly congruent tibial insert prevents the anterior translation of the patella in cruciate-retaining total knee arthroplasty, thus causing inferior clinical scores. It provided useful information about the biomechanical role of the patella in total knee arthroplasty, allowing to choose the most appropriate surgical approach. LEVEL OF EVIDENCE: Case series, Level IV.

Three different cruciate-sacrificing TKA designs: minor intraoperative kinematic differences and negligible clinical differences.

PURPOSE: The goal of this study was to compare three types of mobile-bearing posterior cruciate ligament (PCL)-sacrificing TKA. The hypothesis was that the three designs provide differences in flexion stability and femoral rollback and improved clinical score at 2-year follow-up. METHODS: Three groups of patients, divided according to implant design, were analysed retrospectively. All operations were guided by a non-image-based navigation system that recorded relative femoral and tibial positions in native and implanted knees during: passive range of motion and anterior drawer test at 90° flexion. WOMAC, KSS and SF36 scores were collected pre-operatively and at 2-year follow-up. RESULTS: There are no differences in kinematic or clinical performance of the three implants, except for the antero-posterior translation during stress test in flexion: only Cohort B had comparable pre- and post-operative laxity test values (p < 0.001). All three TKA designs allowed to maintain pre-operative tibial rotation pattern through all range of knee flexion. All clinical scores of the three patient cohorts were significantly improved post-operatively compared to the pre-operative values (p < 0.001). Moreover, we found no differences among post-operative results of the three designs. CONCLUSION: Despite design variations, mobile-bearing PCL-sacrificing TKA reproduces femoral rollback and screw-home with little or no difference in clinical or functional scores at a follow-up of 2 years. LEVEL OF EVIDENCE: III.

In vivo kinematic evaluation of anatomic double-bundle anterior cruciate ligament reconstruction.

BACKGROUND: There is controversy regarding the functional role of the posterolateral (PL) bundle of the anterior cruciate ligament (ACL). PURPOSE: To evaluate the in vivo function of the PL and anteromedial (AM) bundles of the ACL during anatomic double-bundle (DB) ACL reconstruction for acute, isolated ACL tears utilizing a computer navigation system to track intraoperative knee kinematics. STUDY DESIGN: Controlled laboratory study. METHODS: Fifteen patients with acute, isolated ACL tears who underwent anatomic DB ACL reconstruction formed the sample for this study. During surgery, knees were examined by a clinician preoperatively, after fixation of the PL bundle, and after fixation of both the PL and AM bundles. An image-free computer navigation system with custom-made software recorded the data during kinematic tests. The examination consisted of the Lachman and anterior drawer tests, internal-external rotation at 30° of knee flexion, and varus-valgus rotation at 30° of knee flexion. Paired Wilcoxon tests were performed to evaluate the effects of each bundle. The comparisons included ACL-deficient to PL bundle-reconstructed knees, ACL-deficient to DB ACL-reconstructed knees, and PL bundle-reconstructed to DB ACL-reconstructed knees. Significance was set at P < .017 to account for the multiple comparisons. RESULTS: Fixation of the PL bundle significantly improved knee laxity during the Lachman and anterior drawer tests as well as internal-external rotation at 30° of knee flexion (P < .017 for all tests). The addition of the AM bundle further improved knee laxity during the Lachman and anterior drawer tests compared with PL bundle fixation as well as during varus-valgus rotation at 30° of knee flexion compared with ACL-deficient knees (P < .017 for all tests). CONCLUSION: This in vivo study demonstrates that isolated PL bundle reconstruction improves laxity in an ACL-deficient knee and that the addition of the AM bundle improves laxity parameters further. CLINICAL RELEVANCE: Abnormal knee kinematics is known to be linked to the earlier onset of osteoarthritis and lower rates of return to sport. This study suggests that both the AM and PL bundles are important to stabilize ACL-deficient knees.

Comparison of stability and kinematics of the natural knee versus a PS TKA with a 'third condyle'.

PURPOSE: The goal of this study was to compare the kinematics of knees before and after total knee arthroplasty (TKA) that relies on an inter-condylar 'third condyle'. The hypothesis was that the 'third condyle' provides sufficient flexion stability and induces a close to normal femoral rollback, thus granting natural joint kinematics. METHODS: Intra-operative navigation data were collected from 29 consecutive cases that received a cemented TKA (HLS Noetos, Tornier SA, France) designed with an inter-condylar 'third condyle' that engages within the tibial insert beyond 35° flexion. Operations were guided by a non-image-based system (BLU-IGS, Orthokey Italia srl, Italy) that recorded relative femoral and tibial positions in native and implanted knees during: passive range of motion, anterior drawer test at 90° flexion, and varus-valgus stress tests at full extension and at 30° flexion. RESULTS: The total internal tibial rotation during flexion was similar for native (8.2 ± 4.2°) and implanted knees (8.0 ± 5.4°). The lateral femoral condyle was more posterior in implanted knees (1.2 ± 9.4 mm) than in native knees (9.5 ± 3.6 mm) throughout early flexion (p < 0.01), but this difference diminished beyond 100° flexion (n.s.). The implanted knees did not exhibit paradoxical external tibial rotation. Varus-valgus laxity in full extension was lower for implanted knees than for native knees (p = 0.0221), but at 30° flexion was almost identical for both native and implanted knees. Anteroposterior laxity was similar in implanted and native knees. CONCLUSIONS: The 'third condyle' TKA provides similar anteroposterior and mediolateral stability to the natural knee. This feature granted an adequate balance between laxity and constraint to reproduce natural joint kinematics, including smooth femoral rollback, without causing paradoxical external tibial rotation.

Minimum thickness of all-poly tibial component unicompartmental knee arthroplasty in patients younger than 60 years does not increase revision rate for aseptic loosening.

PURPOSE: Management of unicompartmental knee osteoarthritis in middle-aged patients is a challenging problem. Despite its functional advantages, UKA still raises questions concerning implant survivorship and an increased revision risk for aseptic loosening mainly due to polyethylene wear. The main purpose of the present study was to investigate whether using the minimum thickness of an all-poly tibial UKA in patients under 60 years of age increases the revision rate for aseptic loosening. The secondary purposes were to compare implant survivorship with data reported in literature and to prospectively evaluate the clinical outcome in this selected group of patients. METHODS: Thirty-three consecutive patients under 60 years of age at the time of surgery with isolated medial compartment osteoarthritis underwent a unilateral medial UKA from 2002 to 2005 and were prospectively followed. A Kaplan-Meier analysis was performed to determine the 8-year implant survivorship with revision for any reason as endpoint. KSS, WOMAC, Tegner-Lysholm, Tegner and VAS scores were prospectively evaluated at 3- to 8-year follow-up. Weight-bearing radiographs were collected pre-operatively and at 3- to 8-year follow-up to prospectively evaluate hip-knee-ankle angle (HKA), femoro-tibial angle (FTA), tibial plateau angle and posterior tibial slope. RESULTS: The 8-year Kaplan-Meier survivorship with revision for any reason as endpoint was 83 %. Five failures were reported, and in 3 patients' aseptic loosening of the tibial component was the reason for failure. All clinical scores significantly improved at 3-year follow-up, and no further modification was demonstrated up to 8-year follow-up. HKA, FTA and TPA had a significant difference at 3-year follow-up with respect to pre-operative values (p < 0.01) and no further difference at 8-year follow-up was found. CONCLUSIONS: The present study failed to demonstrate an increased revision rate for aseptic loosening of the implant in patients under 60 years of age, who received an all-poly tibial component UKA using the minimum thickness of the implant in all cases.

Are the tubular grafts in the femoral tunnel in an anatomical or isometric position in the reconstruction of medial patellofemoral ligament?

PURPOSE: The purpose of this study was to evaluate the biomechanical results from the in vitro reconstruction of medial patellofemoral ligament (MPFL) using a navigation-assisted technique on a cadaveric model and its effects on patellar stability and kinematics. The authors investigated the hypothesis that patellar kinematics after reconstruction with a tubular graft are not optimal when compared with the original fan-shaped MPFL. METHODS: In six fresh-frozen cadaveric knees, lateral loads (25 N) were applied on the patella at 0°, 30°, 60° and 90° of knee flexion in three different MPFL states: intact, cut and reconstructed. The arrangement allowed positional measurements of patellar motion to be tracked in six degrees of freedom. Medial to lateral patellar translation and patellar tilt were recorded. The kinematics after a technique of MPFL reconstruction, performed with a gracilis tendon in a blind femoral tunnel guided by navigation, were compared against kinematics recorded in the MPFL intact state. A temporary fixation of adequate tension to engage the lateral patellar facet in extension was applied to the MPFL and, after graft cycling, the final fixation was done at 70° knee flexion with an interference screw. RESULTS: There was a comparable medial to lateral patellar translation and tilting of the patella in the MPFL-intact and the MPFL-reconstructed state. Static patellar translation in the MPFL-reconstructed state, with and without the application of load, was comparable to patellar translation in the MPFL-intact state. The dynamic patellofemoral shift kinematics recorded an under-constraint in early flexion and over-constraint in late flexion, while an opposite effect was recorded in patellar tilt. However, these differences were not statistically significant. CONCLUSION: The study confirmed the major role of the MPFL in case of medial loading between 0° and 60°, by focusing on the importance of kinematically identifying the proper femoral point for fixation. While the study demonstrates the importance of kinematic determination of the proper femoral point of fixation, as the anatomical insertion remains difficult to identify. Even in dissected cadavers, the authors recorded a slightly anterior placement than native MPFL. After reconstruction, patellar stability in terms of lateral translation and tilt was similar to the intact MPFL, but patellar kinematics were not optimal with the use of a smaller and tubular graft than the native wider and fan-shaped MPFL.

The adductor tubercle: a reliable landmark for analysing the level of the femorotibial joint line.

PURPOSE: The ratio of femoral width and distance from medial epicondyle to joint line helps estimate the femoral joint line position from femoral width. The approximately radial position of the medial epicondyle on femoral condyle spheres is probably responsible for this relationship, The adductor tubercle approximately lies diametrically opposite to the joint line on condylar sphere. Then, a linear correlation could also exist between the femoral width and distance of adductor tubercle to joint line and is the purpose of the current study. METHODS: Femoral width, along with the distance to joint line from the medial epicondyle, the adductor tubercle and fibular pole, was measured on 110 standard antero-posterior knee radiographs. Correlation between femoral width and these measurements was evaluated. The individual ratio of FW with adductor tubercle joint line, medial epicondyle joint line and fibula joint line was calculated using linear regression analysis. Intra-observer and inter-observer reliability was assessed. RESULTS: Linear correlation was found between femoral width and distance of adductor tubercle to joint line (r = 0.83). It was more reliable than the correlation between femoral width and distance from medial epicondyle to joint line (r = 0.52). Inter-observer repeatability was better for distance from adductor tubercle to joint line than for distance from medial epicondyle to joint line. CONCLUSIONS: We conclude that adductor tubercle can be used as a morphologic landmark to determine the knee joint line position, because a linear correlation between femoral width and distance from the adductor tubercle to the joint line was found.

The influence of medial patellofemoral ligament on patellofemoral joint kinematics and patellar stability.

PURPOSE: Retinacular restraints have a critical role in patellar tracking, limiting the movement of the patella in the trochlear groove. The medial patellofemoral ligament (MPFL) is probably the main stabilizer against lateral displacement; few studies are focused on MPFL role on patellofemoral kinematics and patellar stability. The main goal of this in vitro study was to analyse the influence of the MPFL on the kinematics of the patellofemoral joint and patellar stability. METHODS: Using a non-image-based navigation system, kinematics and anatomical data of six fresh-frozen specimens were collected. A passive flexion-extension from 0° to 90° and static acquisitions at 0°, 30°, 60° and 90°, with and without 25 N of lateral load, were performed with intact and resected MPFL with a 60 N axial force applied to the isolated quadriceps tendon. Patellar tilt and shift were analysed. RESULTS: The MPFL intact state showed a shift in medial direction during the first degrees of knee flexion-that disappeared in MPFL resected condition-followed by a lateral shift, similar to that of MPFL resected condition. Tilt analysis showed that patella rotated laterally until 85° of knee flexion for intact MPFL condition and until 70° for resected MPFL condition and after rotated medially. Static tests showed that patellar stability was significantly affected by MPFL resected condition in particular at 30° and 60°. CONCLUSIONS: The MPFL has an aponeurotic nature. It works as a restraint during motion, with an active role under high stress on lateral side, but with a small contribution during neutral knee flexion. Its biomechanical behaviour under loading conditions should be kept into account when performing surgical reconstruction of this ligamentous structure.

An original clinical methodology for non-invasive assessment of pivot-shift test.

Even if pivot-shift (PS) test has been clinically used to specifically detect anterior cruciate ligament (ACL) injury, the main problem in using this combined test has been yet associated with the difficulty of clearly quantifying its outcome. The goal of this study was to describe an original non-invasive methodology used to quantify PS test, highlighting its possible clinical reliability. The method was validated on 66 consecutive unilateral ACL-injured patients. A commercial triaxial accelerometer was non-invasively mounted on patient's tibia, the corresponding 3D acceleration was acquired during PS test execution and a set of specific parameters were automatically identified on the signal to quantify the test. PS test was repeated three times on both injured and controlateral limbs. Reliability of the method was found to be good (mean intra-rater intraclass correlation coefficient was 0.79); moreover, we found that ACL-deficient knees presented statistically higher values for the identified parameters--than the controlateral healthy limbs, averagely reporting also large effect size.

Single-bundle patellar tendon versus non-anatomical double-bundle hamstrings ACL reconstruction: a prospective randomized study at 8-year minimum follow-up.

PURPOSE: The purpose of this study was to compare subjective, objective and radiographic outcome of the lateralized single-bundle bone-patellar tendon-bone autograft with a non-anatomical double-bundle hamstring tendons autograft anterior cruciate ligament (ACL) reconstruction technique at long-term follow-up. METHODS: Seventy-nine non-consecutive randomized patients (42 men; 37 women) with unilateral ACL insufficiency were prospectively evaluated, before and after ACL reconstruction by means of the above-mentioned techniques, with a minimum follow-up of 8 years (range 8-10 years; mean 8.6 years). In the double-bundle hamstrings technique, we used one tibial and one femoral tunnel combined with one "over-the-top" passage, cortical staple's fixation and we left intact hamstrings' tibial insertion. Patients were evaluated subjectively and objectively, using IKDC score, Tegner level, manual maximum displacement test with KT-2000™ arthrometer. Radiographic evaluation was performed according to IKDC grading system, and re-intervention rate for meniscal lesions was also recorded. RESULTS: The subjective and objective IKDC were similar in both groups while double-bundle hamstrings group showed significantly higher Tegner level (P = 0.0007), higher passive range of motion recovery (P = 0.0014), faster sport resumption (P = 0.0052), lower glide pivot-shift phenomenon (P = 0.0302) and lower re-intervention rate (P = 0.0116) compared with patellar tendon group. Radiographic evaluation showed significant lower objective degenerative changes in double-bundle hamstrings group at final follow-up (P = 0.0056). CONCLUSION: Although both techniques provide satisfactory results, double-bundle ACL reconstruction shows better functional results, with a faster return to sport activity, a lower re-operation rate and lower degenerative knee changes.

Computer-assisted anterior cruciate ligament reconstruction: an evidence-based approach of the first 15 years.

In the last 15 years, computer-assisted surgery (CAS) has been used for many purposes during anterior cruciate ligament (ACL) reconstruction, such as tunnel positioning, joint laxity evaluation, and biomechanical studies. This article is an evidence-based literature review of the contribution of such technology to ACL surgery. A search of the PubMed and Medline databases was performed. Articles were classified according to the study design and to the research topic: anatomy, laxity, kinematics, and comparison of surgical techniques. An evidence-based approach was used to verify the clinical usefulness of CAS to ACL surgery. The use of CAS for research purposes was also evaluated. CAS was shown to improve femoral tunnel positioning, even if clinical outcomes showed no differences compared with manual techniques. CAS technology was found to be useful for research purposes in terms of providing a better comprehension of the effect of different ACL reconstructions and of the different bundles on joint laxity, as well as describing tunnel positioning in relation to native ACL insertion. CAS in ACL surgery can improve results at time 0 and can improve knowledge about ACL anatomy and kinematics. Its application remains limited mostly to research purposes because of the invasiveness of the system and the absence of improved clinical results at follow-up.

Clinical relevance of static and dynamic tests after anatomical double-bundle ACL reconstruction.

A computer navigation system was used to collect kinematic data of 18 subjects undergoing ACL reconstruction. Surgical procedure was an anatomical four-tunnel hamstring double-bundle reconstruction. Static laxity and dynamic laxity were analyzed before and after graft passage and fixation. Correlations between static and dynamic laxities as well as with the preoperative IKDC score were determined. Static and dynamic laxities were significantly reduced after anatomic double-bundle ACL reconstruction (P < 0.05). There were no significant correlations between static and dynamic laxities (r < 0.4, P > 0.05). The preoperative IKDC score was only related to preoperative dynamic laxity (P < 0.01). The dynamic evaluation of pivot shift is able to better describe knee laxity, in particular rotational laxities and has no correlation with static laxity.

Pivot-shift test: analysis and quantification of knee laxity parameters using a navigation system.

Lachman, drawer, and pivot-shift (PS) tests are important in the assessment of ACL reconstruction. The goal of this work was to analyze the reliability of the PS test using a navigation system, identifying a set of new quantitative parameters and evaluating their clinical relevance. Eighteen patients that underwent anatomic double-bundle ACL reconstruction were included. The new dynamic parameters were: anteroposterior translation of the medial and lateral compartments and the joint center and internal/external and varus/valgus rotations of the joint. For each parameter we measured the peaks and the areas obtained during the test. Intratester repeatability, comparisons of pre- and postoperative laxities, and correlations between the PS peaks and the corresponding peaks obtained with standard static tests were evaluated. Areas, peaks, and static laxity outcomes were compared, grouping patients according to the preoperative International Knee Documentation Committee (IKDC) score. The PS test was reliable in identifying the surgical reconstruction. Correlation analysis showed good coefficients both for pre- and postoperative values. Patients with IKDC grade "D" had larger areas during the PS compared to patients with grade "C". Our analysis is helpful for characterizing patient-specific laxity and surgical performance, thus highlighting the clinical relevance of the PS test.

Minimally invasive unicompartmental knee replacement: retrospective clinical and radiographic evaluation of 83 patients.

We performed a retrospective clinical and radiographic evaluation of 83 nonconsecutive patients operated in our institute between February 1996 and March 2003 with a mean follow-up of 60 months to assess the efficiency of unicompartmental knee replacement (UKR) performed with a minimally invasive technique. The aim of this study was to correlate the clinical outcome with the pre- and post-operative alignment and with implant positioning on coronal and sagittal plane. Eighty-three nonconsecutive patients (60 males, 23 females) underwent cemented UKR (De Puy Preservation Uni with all-poly tibial component), for both medial OA (80 patients) and AVN of the medial femoral condyle (3 patients). All patients were available at final follow-up evaluation, and they all presented an evident varus alignment at pre-operative clinical and radiographic evaluation. At radiographic measurement, we considered a knee with femoro-tibial angle (FTA) > 175 degrees as varus knee, 170 degrees < FTA < 175 degrees as normal knee and a knee with a FTA < 170 degrees as a valgus knee. Moreover, we considered a tibial plateau angle (TPA) > 90 degrees for valgus knee and a TPA < 90 degrees for varus knee. According to Hospital for Special Surgery (HSS) scoring system, at a mean follow-up of 60 months, 61 (74%) cases were excellent (100-85 points), 15 (18%) cases were good (84-70 points) and 7 cases (8%) had fair results (<70 points). In our series, patients with an excellent clinical result presented a mean varus deformity of 7.2 degrees (3.6 degrees-10.8 degrees) pre-operatively. According to literature, we demonstrated that a small amount of undercorrection with a small amount of residual varus deformity of 3 degrees-5 degrees is the goal to be reached in order to avoid both rapid degeneration of the nonreplaced compartment and the premature loosening of the replaced compartment. We performed a mean axial correction of 5 degrees (SD 3.9 degrees), leaving a mean axial varus deformity of 2.2 degrees in the excellent group. In our series, the group with excellent results also showed a post-operative PTS of 7 degrees (2.4 degrees-11.6 degrees), while mean pre-operative PTS was 6.5 degrees (2.7 degrees-10.3 degrees). In this study, results have shown that minimally invasive UKR producing a small amount of varus undercorrection in selected patients with medial tibio-femoral osteoarthritis or moderate avascular necrosis of the medial femoral condyle provides excellent clinical and functional results. Overcorrection of varus malalignment with a UKR may produce both rapid degeneration of the lateral tibio-femoral compartment and the early failure of the replaced compartment.

Reliability of a navigation system for intra-operative evaluation of antero-posterior knee joint laxity.

BACKGROUND: The purpose of this study was to investigate about the reliability of measuring antero-posterior laxity within-subjects for in-vivo studies using a navigation system. METHODS: The analysis was performed by enroling 60 patients undergoing anterior cruciate ligament ACL reconstruction, and assessing AP laxity during the Lachman and drawer tests. RESULTS: For the navigation system standard deviation for intra-trial measures was 0.7 mm, thus the intra-trial repeatability coefficient was 2.2 mm; standard deviation for intra-trial measure was 1.2 mm, while the reference inter-trial repeatability coefficient between expert surgeons was 3.4 mm. CONCLUSIONS: In conclusion, this study suggests that KIN-Nav may represent a new method to measure and document AP laxity intra-operatively with improved accuracy and test the effect of surgical treatment in-vivo with higher sensitivity than in the past and this study quantify its reliability for within-subjects studies performed by a single expert surgeon.