The Results of Recurrent Patellar Dislocation Treatment With MPFL Reconstruction in Adolescents With a Minimum Three-year Follow-up: A Prospective Study

PurposeThe aim of this prospective study is to perform a clinical and radiological assessment of the results of surgical treatment in a homogenous group of adolescents with recurrent patellar dislocation (RPD), using medial patellofemoral ligament (MPFL) reconstruction as the basic technique. MethodsTwenty-two patients reported to the follow-up examination after at least three years, including four patients who underwent bilateral surgery (26 knees). The mean age at the time of the surgery was 15.4 years. The subjects were asked to complete the Lysholm-Tegner Knee Scale and the Kujala Anterior Knee Pain Scale before surgery and after follow-up. Based on the imaging results, the Caton-Deschamps Index (CDI), congruence angle (CA), patellofemoral angle (PFA) and Wiberg classification of the patella shape were assessed. ResultsTwo incidents of patellar redislocation was noted. Both the Lysholm-Tegner and Kujala Scale scores significantly improved after follow-up (p<0.001). CDI did not change significantly (p=0.681). The values of both PFA and CA significantly decreased after surgery (p<0.001). An incorrect congruence angle (patellar shift) was present in 22 knees pre-op and ten post-op (p=0.002). Increased patellofemoral angle (patellar tilt) was present in 21 knees pre-op and seven post-op (p<0.001). A statistically significant correlation was demonstrated between PFA and both Lyscholm-Tegner and Kujala score (in both p<0.001, r=-0.5). A slight, but significant, correlation was found between CA and Kujala score (p=0.008, r= -0.036). ConclusionSurgical treatment causes a considerable improvement in the functional assessment of patients, as well as anatomical conditions within the patellofemoral joint.ClinicalTrials.gov record No PMMHRI-BCO.34/2019ClinicalTrials.gov Identifier: NCT03983213https://clinicaltrials.gov/ct2/show/NCT03983213Registered 06/12/2019 - Retrospectively registered

Increased tibial tubercle-trochlear groove and patellar height indicate a higher risk of recurrent patellar dislocation following medial reefing

Purpose Identifying anatomical risk factors on recurrent dislocation after medial reefing is important for deciding surgical treatment. The present study aimed to retrospectively analyze the preoperative magnetic resonance imaging (MRI)-based parameters of patients treated with medial reefing and whether these parameters lead to a higher risk of recurrent dislocation. Methods Fifty-five patients (18.6 ± 6.6 years) who underwent medial reefing after primary traumatic patellar dislocation (84% with medial patellofemoral ligament [MPFL] rupture) were included. Patients were followed up for at least 24 months postoperatively (3.8 ± 1.2 years) to assess the incidence of recurrent patellar dislocation. In patients without recurrent dislocation, the Kujala and subjective IKDC scores were assessed. Moreover, the tibial tubercle-trochlear groove (TT-TG), sulcus angle, patellar tilt, patellar shift, and lateral trochlea index (LTI) were measured. The patellar height was measured using the Caton-Dechamps (CDI), Blackburne-Peel (BPI), and Insall-Salvati index (ISI). The cohort was subclassified into two groups with and without recurrent dislocation. Differences between groups were analyzed with respect to the MRI parameters. Results Forty percent had a pathological sulcus angle of > 145°, 7.2% had an LTI of < 11°, 47.3% had a patellar tilt of > 20°, and 36.4% had a TT-TG of ≥ 16 mm. Increased patellar height was observed in 34.5, 65.5, and 34.5% of the patients as per CDI, BPI, and ISI, respectively. Nineteen (34.5%) patients suffered from recurrent dislocation. Compared with patients without recurrent dislocation, those with recurrent dislocation had a significantly lower LTI (p = 0.0467). All other parameters were not significantly different between the groups. Risk factor analysis showed higher odds ratios (OR > 2), although not statistically significant, for MPFL rupture (OR 2.05 [95% confidence interval 0.38–11.03], LTI (6.6 [0.6–68.1]), TT-TG (2.9 [0.9–9.2]), and patellar height according to ISI (2.3 [0.7–7.5]) and CDI (2.3 [0.7–7.5])). Patients without recurrent dislocation had a Kujala score of 93.7 ± 12.1 (42–100) points and an IKDC score of 90.6 ± 11.7 (55.2–100) points. Conclusion Anatomical, MRI-based parameters should be considered before indicating medial reefing. A ruptured MPFL, an LTI < 11°, a TT-TG ≥ 16 mm, a patellar tilt > 20 mm, and an increased patellar height according to ISI and CDI were found to be associated, although not significantly, with a higher risk (OR > 2) of recurrent patellar dislocation after medial reefing. Thorough preoperative analysis is crucial to reduce the risk of recurrent dislocation in young patient cohorts. Level of evidence Level IV

Arthroscopic lateral retinacular release improves patello-femoral and femoro-tibial kinematics in patients with isolated lateral retinacular tightness

Purpose Arthroscopic lateral retinacular release (LRR) has long been considered the gold standard for the treatment for anterior knee pain caused by lateral retinacular tightness (LRT). However, one-third of patients experience continuous pain postoperatively, which is thought to be related to persistent maltracking of the patella and altered femoro-tibial kinematics. Therefore, the aim of the present study was to simultaneously assess femoro-tibial and patello-femoral kinematics and identify the influence of arthroscopic LRR. Methods Sixteen healthy volunteers and 12 patients with unilateral, isolated LRT were prospectively included. Open MRI scans with and without isometric quadriceps contraction were performed in 0°, 30° and 90° of knee flexion preoperatively and at 12 months after surgery. Patellar shift, tilt angle, patello-femoral contact area and magnitude of femoro-tibial rotation were calculated by digital image processing. Results Postoperatively, patellar shift was significantly reduced at 90° of knee flexion compared to preoperative values. The postoperative patellar tilt angle was found to be significantly smaller at 30° of knee flexion compared to that preoperatively. Isometric muscle contractions did not considerably influence patellar shift or tilt in either group. The patello-femoral contact area increased after LRR over the full range of motion (ROM), with significant changes at 0° and 90°. Regarding femoro-tibial kinematics, significantly increased femoral internal rotation at 0° was observed in the patient group preoperatively, whereas the magnitude of rotation at 90° of knee flexion was comparable to that of healthy individuals. The pathologically increased femoral internal rotation at 30° without muscular activity could be significantly decreased by LRR. With isometric quadriceps contraction no considerable improvement of femoral internal rotation could be achieved by LRR at 30° of knee flexion. Conclusions Patello-femoral and femoro-tibial joint kinematics could be improved, making LRR a viable surgical option in carefully selected patients with isolated LRT. However, pathologically increased femoral internal rotation during early knee flexion remained unaffected by LRR and thus potentially accounts for persistent pain. Level of evidence II.

The Effect of Partial Lateral Facetectomy of the Patella on the Radiographic and Clinical Outcome of Unresurfaced Patellar-retaining Total Knee Arthroplasty

Background: Management of patellar maltracking during primary TKA is of considerable importance. Lateral release, which is generally performed for this purpose, is associated with several complications. Objectives: In this study, we aimed to evaluate the role of partial lateral facetectomy in tracking the patella in Total Knee Arthroplasty (TKA). Methods: In a retrospective study, the efficiency of partial lateral facetectomy of the patella in achieving proper tracking of the patella was evaluated in 116 patients who underwent unresurfaced patellar-retaining TKA. The radiographic outcome measures included the patellar tilt and patellar shift. The functional outcome was assessed with Kujala anterior knee pain scale. Results: The Mean±SD age of the patients was 66.3±7.6 years. The mean follow-up of patients was ‎‎20.6±8.9 months. The Mean±SD patellar tilt was ‎‎10.5±7.2‎‎‏°‎‏ before the surgery and ‏‎4.4±5‎‎‏° after ‏the operation ‏‎ (‎P‎<‎‏0.001‏‎). ‎The Mean±SD preoperative patellar shift was ‏‎3.3±4.3‎‏ mm which improved to ‏‎-‎‎0.2±2.8°‎‏ after the surgery ‏‎(‎P‎<‎‏0.001‏‎). ‎The Mean±SD Kujala score of the patients was ‏‎74.6±7.1‎, ‎‏ ‏ranging ‎from 54 ‏to ‎‏89. ‎No complication was recorded during the follow‎-‎up period. Conclusion: Partial lateral facetectomy of the patella provides an acceptable radiographic and ‎functional outcome in patients undergoing primary TKA. Therefore, it could be regarded as a ‎valuable alternative to lateral release in unresurfaced patellar-retaining TKA.‎

Changes of Sagittal and Axial Alignments of Patella after Open- and Closed-Wedge High-Tibial Osteotomy: A Systematic Review and Meta-Analysis

The present systematic review and meta-analysis were aimed to verify the effect of open-wedge (OW) and closed-wedge (CW) high-tibial osteotomy (HTO) on sagittal and axial alignments of the patella. A vigorous search was performed for studies that compared the changes of sagittal and axial alignments of patella after OW and CW HTO. After evaluating publication bias and heterogeneity, we aggregated variables by using the random-effects model. The weighted mean differences in sagittal and axial alignment of patella were estimated with 95% confidence intervals. Also, we analyzed the changes in sagittal alignment of various OW HTO techniques, such as uniplanar, biplanar, and retrotubercle osteotomy. Overall, 20 studies that included 831 OW HTOs and 206 CW HTOs were included in this study. Patellar height decreased after OW HTO based on the Blackburne–Peel index (BPI, mean: −0.10), and Caton–Deschamps index (CDI, mean: −0.08). However, the patellar height after CW HTO showed no change after surgery (BPI [mean: −0.02], and CDI [mean: 0.02]). Among OW HTO techniques, the retrotubercle osteotomy showed the least change in patellar height after surgery. The lateral patellar tilt decreased by 1.74 degrees, and lateral patellar shift showed no change after OW HTO. However, there was a lack of evidence to conclude the change of axial alignment of patella after CW HTO. Our results supported that the sagittal alignment of patella lowered after OW HTO. However, CW HTO maintained the constant sagittal position of the patella. Among OW HTO techniques, the retrotubercle osteotomy had the least effect on the sagittal alignment of the patella. Regarding the axial alignment of the patella, OW HTO resulted in a little change of lateral patellar tilt; however, there was little evidence to confirm the change of the axial alignment of patella after CW HTO.

Medial Patellofemoral Ligament Reconstruction in Skeletally Immature Patients

Objectives: To evaluate the clinical outcome after medial patellofemoral ligament (MPFL) reconstruction for patellofemoral instability in skeletally immature patients. Methods: Study participants were 8 patients ( median age, 10 years; range, 5-14 and one male , others female) who had suffered from persistent patellofemoral instability. Our technique preserves femoral and patellar insertion anatomy of MPFL using a free semitendinosus autograft, together with tenodesis to the adductor magnus tendon thus sparing the open physis of distal femur and the patellar attachment of MPFL. The clinical results were evaluated preoperatively and the final follow-up period using the Kujala patellofemoral score. Patellar shift, tilt and height were measured preoperatively and on the latest follow-up on plain radiographs. Results: At average 42 months follow-up ( range, 16 to 56), %80 of patients were satisfied with the treatment. Redislocation or instability symptoms occurred in two patients. No apprehension signs or redislocations were seen in the remanining six patients. A significant improvement (p&#x2039;0.05) in Kujala score (from 36 to 77) was found. Patellar shift & tilt decreased to anatomic values in six patients but patella alta persisted. Conclusion: The result of this study show that MPFL reconstruction with our technique seems to be an effective treatment for recurrent and habitual patellofemoral dislocation in skeletally immature patients; leading to significant increases in stability and functionality.

Patellar Tracking during the Gait Cycle

Purpose. To assess normal patellar tracking during walking using the 9-camera infrared system. Methods. Four men and 6 women aged 25 to 33 (mean, 29) years each performed 16 walking trials on one occasion. They had prominent patellae with minimal soft tissues (minimising skin artefacts), and their knees and lower limbs were normal and symmetrical. 12 retro-reflective markers (2.5 cm in diameter) were taped to anatomic landmarks of the lower body. Two additional markers (1.4 cm in diameter) were first placed on the medial and lateral points and then proximal and distal points of the patella. Patellar motion relative to the centre of the knee joint was defined as angles between the centre of the knee joint and the 2 sets of patellar markers (medial-lateral and proximal-distal). The mean, maximum, and minimum values of these angles in a standing position were recorded, as was patellar tracking during walking. The X, Y, and Z coordinates for each marker were smoothed out throughout the capturing time. A single gait cycle per trial was chosen for analysis. Results. During walking, the centre of the knee joint and the patella did not move in unison, and the extent of separation was subject dependent. In 70% of the participants, the maximum angle between the centre of the knee joint and each set of markers occurred in the swing phase (0–43%) of the gait cycle. When analysing both sets of markers together, the percentage of participants became 60%. The extent of knee flexion was subject dependent. There was more medial-lateral motion (shift) of the patella than proximal-distal (tilt) motion during the gait cycle. These indicated that the maximum amount of patellar shift and tilt occurred in the swing and early stance phases of the gait cycle and that abnormal patellar motion can be detected if excessive shift or tilt occurs outside of these phases. Conclusion. Patella mal-tracking could be attributed to the position of the lower body segments rather than the absorption or generation of forces.

Intraoperative patellar kinematics following resection of the central one-third of the patellar tendon in the ovine stifle joint

SummaryObjectives: The bone-patellar tendon-bone complex is routinely harvested for anterior cruciate ligament reconstruction in humans. Patella infera may ensue. However, the contribution from resection of the central one-third of the patellar tendon (PT) to potentially altered patellofemoral kinematics, in addition to those induced by a positional shift of the patella, are yet to be distinguished. Objectives of this study were to characterize changes in intraoperative patellar kinematics and PT length in nine sheep immediately following unilateral resection of the central one-third PT, and again at six, 12 and 24 weeks postoperatively.Methods: Following implantation of bone-screws into the patella and tibia, electromagnetic receivers were anchored to these, and then passively-induced, unloaded patellar kinematics were captured. Patellar kinematics were referenced to the tibial coordinate frame and analysed using non-parametric tests (Wilcoxon Signed Rank Test).Results: Resection alone did cause significant alteration in kinematics at the time of surgery (p <0.05). Postoperatively, a mean increase in PT length of 2.6 mm was detected in the operated stifles, reflected partly as a net 2.8 mm proximal patellar shift (p <0.001). This was accompanied by a mean net six degree medial shift in the patellar tilt pattern (p <0.001). Significant changes to patellar spin in the latter parts of flexion were also observed (p <0.005). Kinematic and length changes did not recover up to 24 weeks postoperatively.Clinical significance: The data obtained in this study suggests that both the patellar height and integrity of the PT are important determinants of patellar kinematics in the ovine stifle joint.

Relationship Between Three-Dimensional Geometry of the Trochlear Groove and In Vivo Patellar Tracking During Weight-Bearing Knee Flexion

It is widely recognized that the tracking of patella is strongly influenced by the geometry of the trochlear groove. Nonetheless, quantitative baseline data regarding correlation between the three-dimensional geometry of the trochlear groove and patellar tracking under in vivo weight-bearing conditions are not available. A combined magnetic resonance and dual fluoroscopic imaging technique, coupled with multivariate regression analysis, was used to quantify the relationship between trochlear groove geometry (sulcus location, bisector angle, and coronal plane angle) and in vivo patellar tracking (shift, tilt, and rotation) during weight-bearing knee flexion. The results showed that in the transverse plane, patellar shift was strongly correlated (correlation coefficient R=0.86, p<0.001) to mediolateral location of the trochlear sulcus (raw regression coefficient βraw=0.62) and the trochlear bisector angle (βraw=0.31). Similarly, patellar tilt showed a significant association with the trochlear bisector angle (R=0.45, p<0.001, and βraw=0.60). However, in the coronal plane patellar rotation was poorly correlated with its matching geometric parameter, namely, the coronal plane angle of the trochlea (R=0.26, p=0.01, βraw=0.08). The geometry of the trochlear groove in the transverse plane of the femur had significant effect on the transverse plane motion of the patella (patellar shift and tilt) under in vivo weight-bearing conditions. However, patellar rotation in the coronal plane was weakly correlated with the trochlear geometry.