Patellar Height Research Articles

Why Determining the Native Length Change Pattern of Medial Patellofemoral Ligament Is Still a Challenge: State-of-the-Art Review of Potential Sources of Heterogeneity within Studies Evaluating Isometry of MPFL

Background: In the literature there are divergent results as to the native MPFL length change pattern. The reason for such divergent results may be the heterogeneity of design of studies analyzing MPFL isometry. The hypothesis of this review was that studies assessing MPFL length change pattern are highly heterogenous. The aim was to present a state-of-the-art review of sources of this heterogeneity. Materials and Methods: A total of 816 records were identified through the initial search of MEDLINE and Scopus databases. After eligibility assessment, 10 original articles and five reviews were included. In the included studies, the following 15 potential sources of heterogeneity were assessed: number of patients/cadavers, age, males to females ratio (demographics), identification of measured fibers, measurement method, measurement precision, quadriceps muscle activity, iliotibial band activity, hamstrings activity (study design), patellar height, trochlear or patellar dysplasia, femoral anteversion, mechanical axis of the limb, tibial tubercle–trochlear groove distance, and condylar anteroposterior dimensions (morphology). Each variable was graded in every included article with 1 point if reported precisely and not introducing bias; or with 0 points if reported not precisely, introducing bias, or not reported at all. Results: Within original articles, the highest achieved score was 10 out of 15 possible points with mean score of 6.7, SD = 2.37, and minimum score of just 3 out of 15 points. In the demographics section, mean score was 2.4, SD = 0.8 (80% of maximum possible score of 3); in the study design section it was 3.1, SD = 1.87 (52% of maximum possible score of 6); and in the morphology section it was 1.5, SD = 1.43 (25% of maximum possible score of 6). Conclusions: There is high heterogeneity and incomplete reporting of potential sources of bias in studies assessing native MPFL length change pattern. Future investigators should be aware of the presented factors and their potential impact on MPFL isometry. All methodologic factors should be meticulously reported. Detailed description of demographic data is already a standard; however, authors should more extensively report variables concerning study design and morphology of patients’ patellofemoral joint. Furthermore, future studies should try to meticulously simulate the real-life working environment of MPFL and ensure usage of proper measurement methods.

L’articulation fémoro-patellaire n’est pas altérée cliniquement après ostéotomie tibiale de valgisation par ouverture médiale

BackgroundAfter high tibial osteotomy (HTO), the loading of the lateral compartment can be increased. Moreover, the change of patellar height may adversely affect the patellofemoral joint and functional outcomes. HypothesisWe hypothesized that the cartilage of the lateral compartment and patellofemoral joint would worsen after open-wedge HTO and the overcorrection of HTO could worsen the cartilage state of the patellofemoral joint. We evaluated the cartilage status and clinical results after medial open-wedge HTO and the factors affecting the outcomes. Materials and methodsFrom 2011 to 2018, 49 patients who had a mean age of 54.9 years and who underwent medial open-wedge HTO were selected. Plate removal was performed at a mean of 37.0 (range, 13–89) months after HTO, whereas diagnostic arthroscopy was performed during medial open-wedge HTO and plate removal. The cartilage status of each joint and the clinical results, including the Hospital for Special Surgery (HSS) score, Knee Society knee score (KS) and function score (FS), and patellar score, were compared. We evaluated the postoperative changes in the cartilage status and clinical scores. Additionally, we evaluated whether the postoperative correction degree could affect the clinical results. ResultAfter medial open-wedge HTO, the patellar height decreased. There was no change in the cartilage at the patellar and femoral trochlear groove. The HSS score, KS, and FS improved, but the patellar score remained unchanged. In the overcorrection group, the cartilage status significantly deteriorated at the lateral tibia condyle as compared with that in the undercorrection group. Higher preoperative clinical scores were associated with less postoperative improvement. Discussion and conclusionThe outcomes in the patellofemoral joint, including the cartilage condition and clinical scores, did not change after open-wedge HTO, despite patellar infera. Additionally, they were not influenced by the correction degree. Higher preoperative clinical scores were associated with less postoperative improvement. Level of evidenceIV; Retrospective study.

Radiologic Measurements in the Assessment of Patellar Instability: A Systematic Review and Meta-analysis.

Background:Numerous diagnostic imaging measurements related to patellar instability have been evaluated in the literature; however, little has been done to compare these findings across multiple studies.Purpose:To review the different imaging measurements used to evaluate patellar instability and to assess the prevalence of each measure and its utility in predicting instability. We focused on reliability across imaging modalities and between patients with and without patellar instability.Study Design:Systematic review; Level of evidence, 4.Methods:We performed a systematic review of the literature using the PubMed, SCOPUS, and Cochrane databases. Each database was searched for variations of the terms “patellar instability,” “patellar dislocation,” “trochlear dysplasia,” “radiographic measures,” “computed tomography,” and “magnetic resonance imaging.” Studies were included if they were published after May 1, 2009, and before May 1, 2019. A meta-analysis using a random effects model was performed on several measurements, comparing instability and control groups to generate pooled values.Results:A total of 813 articles were identified, and 96 articles comprising 7912 patients and 106 unique metrics were included in the analysis. The mean patient age was 23.1 years (95% CI, 21.1-24.5), and 41% were male. The tibial tubercle–trochlear groove (TT-TG) distance was the most frequently included metric (59 studies), followed by the Insall-Salvati ratio and Caton-Deschamps index (both 26 studies). The interobserver intraclass correlation coefficients were excellent or good for the TT-TG distance and Insall-Salvati ratio in 100% of studies reporting them; however, for the Caton-Deschamps index and Blackburne-Peel ratio, they were excellent or good in only 43% and 40% of studies. Pooled magnetic resonance imaging values for TT-TG distance (P < .01), Insall-Salvati ratio (P = .01), and femoral sulcus angle (P = .02) were significantly different between the instability and control groups. Values for tibial tubercle–posterior cruciate ligament distance (P = .36) and Caton-Deschamps index (P = .09) were not significantly different between groups.Conclusion:The most commonly reported measurements for evaluating patellar instability assessed patellar tracking and trochlear morphology. The TT-TG distance was the most common measurement and was greater in the patellar instability group as compared with the control group. In addition, the TT-TG, tibial tubercle–posterior cruciate ligament, and patellar tendon–trochlear groove distances were highly reproducible measurements for patellar tracking, and the Insall-Salvati ratio had superior reproducibility for assessing patellar height.

Abrasion arthroplasty promotes improvement of degenerated femoral trochlear cartilage after medial open wedge high tibial osteotomy

ObjectivesSeveral studies have reported negative effects of open wedge high tibial osteotomy (OWHTO) on patellofemoral joints with cartilage degeneration and recommended performing other procedures. However, if chondral resurfacing surgery could promote improvement of cartilage degeneration in the patellofemoral joint, OWHTO would be an acceptable option. The purposes of this study were to arthroscopically evaluate the femoral trochlear articular cartilage after abrasion arthroplasty combined with OWHTO and to investigate the factors promoting improvement of that cartilage.MethodsThe present study cohort comprised 18 knees of 18 patients with varus osteoarthritis of the knee who had (1) International Cartilage Repair Society (ICRS) grade 4 femoral trochlear chondral lesions at the time of OWHTO; (2) undergone abrasion arthroplasty of the femoral trochlear cartilage in combination with OWHTO; (3) undergone second-look arthroscopy; and (4) been followed up for more than 2 years. Cartilage status was arthroscopically graded at the time of OWHTO and second-look arthroscopy. Patients were allocated to two groups according to the status of the femoral trochlear cartilage at the time of second-look arthroscopy: the improved group comprised patients with an ICRS grade of less than 3, and the not improved group comprised those with an ICRS grade of 4. Clinical outcomes, expressed as Knee Injury and Osteoarthritis Outcome Score (symptoms, pain, activities of daily living, function in sports/recreation and quality of life) and selected radiographic variables were compared between the two groups.ResultsThere were 11 (61%) knees in the improved group and 7 (39%) in the not improved group. A comparison of radiographic variables between the two groups revealed that neither limb alignment nor patellar height affected cartilage changes. The two groups had similar results on the symptoms, pain, sports/recreation and activities of daily living subscales of the Knee Injury and Osteoarthritis Outcome Score. However, the quality of life subscale significantly differed between the two groups (p=0.025).ConclusionDegenerated femoral trochlear cartilage can improve after combined abrasion arthroplasty and OWHTO. A comparison of clinical outcomes between the improved and not improved groups revealed that neither radiographic variables nor clinical symptoms, including pain, affected cartilage changes at short-term follow-up.Level of evidenceCase series, level V.

The relationship between patellar tilt and quadriceps patellar tendon angle with anatomical variations and pathologies of the knee joint

PurposeTo investigate the association between the knee joint anatomical variations and pathologies, and to describe the quadriceps patellar tendon angle (QPA). MethodsMRIs of 406 cases with a lateral patellar tilt angle (LPT)>5° and a control group of 40 cases with an LPT<5° were retrospectively evaluated. QPA, LPT, trochlear sulcus angle (TSA), tibial tubercle–trochlear groove distance (TT–TG), Insall-Salvati index (ISI), patellar tendon length (PTL), patellar height (PH), lateral trochlear inclination (LTI), trochlear facet asymmetry ratio (TFA) and trochlear depth (TD) were measured. Presence of fat-pad oedema, patellar and trochlear chondromalacia, patellar and quadriceps tendinosis and effusion were evaluated. ResultsThe medians of TSA, PTL, ISI and TT–TG were significantly higher; LTI, TFA and TD were significantly lower in the patient group. The prevalence of SL–Hoffa, non–SL–Hoffa, suprapatellar and prefemoral fat-pad oedema, effusion and chondromalacia were significantly higher in the patient group. LPT was found to be positively correlated with TSA and TT–TG, and negatively correlated with LTI and TD. Cases with trochlear dysplasia, patellar chondromalacia and quadriceps tendinosis had significantly higher LPT. There was a positive correlation between QPA and TSA and a negative correlation between QPA and LTI. Cases with trochlear dysplasia, non–SL–Hoffa oedema, prefemoral fat-pad oedema and quadriceps tendinosis had significantly higher QPA. We found 10°<LPT to be a cut–off value to cause SL–Hoffa fat pad oedema. ConclusionThe anatomical variations of the knee joint are associated with fat-pad, cartilage and tendon pathologies.

Ipsilateral patellofemoral morphological abnormalities are more severe than those of contralateral joints in patients with unilateral patellar dislocation.

To determine the differences in anatomic parameters between ipsilateral dislocated knees and contralateral non-dislocated knees in patients with unilateral patellar dislocation and to identify any variations in ipsilateral knees contributing to contralateral anatomic abnormalities. A total of 82 patients with unilateral patellar dislocation from 2016 to 2019 were retrospectively evaluated. Bilateral anatomic factors, including the tibial tubercle to trochlear groove (TT-TG) distance, lower limb rotational deformities, trochlear dysplasia, patella tilt, and patellar height, were assessed by CT. The study included 46 patients (32 females and 14 males, mean age ± SD 20.5 ± 6.8). The interobserver reliability of each parameter showed excellent agreement. The ipsilateral TT-TG distance (P = 0.004), patella tilt (P = 0.001), and patellar height (P = 0.01) were greater in the ipsilateral knees than in the contralateral knees. The lateral trochlea inclination (LTI) in the contralateral knees was larger than that in the ipsilateral knees (P = 0.022). There was a significant difference in the distribution of trochlear dysplasia of Dejour between the ipsilateral knees (dislocated side) and the contralateral knees (P = 0.036). However, bilateral femoral and/or tibial torsion, and bilateral knee joint rotation did not differ significantly. Binary logistic regression showed that only ipsilateral LTI revealed significant ORs of 8.83 (P = 0.016) and 7.64 (P = 0.018) with regard to contralateral abnormal tibial torsion and LTI, respectively. In patients with unilateral patellar dislocation, the ipsilateral TT-TG distance, patella tilt, and patellar height values were larger in the ipsilateral knees than in the contralateral knees, and trochlear dysplasia was more severe in the ipsilateral joints. The risks of contralateral pathological tibial torsion and LTI were 8.8- and 7.6-fold higher, respectively, in patients with abnormal ipsilateral LTI. Level IV.

Influence of patella height after patella fracture on clinical outcome: a 13-year period

IntroductionThe incidence of patella fracture is statistically low (0.5–1.5%) compared to other fractures of the extremities [Patella fractures 76(10):987–997, 2005]. In the latter research, patella fractures if treated surgically present an overall inferior functional outcome. Little is known about the influence of the postoperative patella height on the clinical outcome. Therefore, the aim of our study was to analyse the influence of the patella height on the patients’ functional outcome after surgery.MethodsIn this retrospective study the in-house trauma register of our level I University trauma center was screened for patients suffering patella fractures treated surgically. Patella height of the same patients was evaluated on lateral X-rays using the Insall–Salvati Ratio (ISR). The patients’ X-rays were analyzed at two time points for the ISR, whereas group A presents ISR data right after surgery and group B data at the latest follow up (minimum 6 weeks). The change of mean ISR at both time points was tested for significance. The functional outcome was measured by the “Munich Knee Questionaire” (MKQ). These MKQ results of different patella heights and fracture types were compared.ResultsThe screening of our in-house trauma register revealed 375 patients between the years 2003 and 2016. Out of these 54 patients (34f, 20 m) were enrolled. In detail the follow-up time for ISR between group A and B accounted for a mean of 503.8 ± 655.7 days. The MKQ was assessed at a mean of 1367.0 ± 1042.8 days after surgery. According to the AO-classification 10% AO.34 type B and 90% AO.34 type C fractures were found. Group A showed in 9.1% a patella baja and in 27.3% a patella alta compared to group B presenting 20.0% patella baja and 14.5% patella alta. There was no significant difference in functional outcome referring to the MKQ in patella alta (MKQ 69.0% ± 18.2) or baja (MKQ 67.1% ± 17.9) (p = 0.9). No significant functional difference between AO34.type B (MKQ 74.5% ± 11.0) and AO34.type C fractures (MKQ 64.0% ± 15.0) resulted (p = 0.1).ConclusionOur results demonstrate that different postoperative patella heights apparently do not influence the functional outcome in the short follow-up.

Clinical Outcomes and Prognostic Factors in Patients With Recurrent Patellar Lateral Dislocation Treated With Isolated Medial Patellofemoral Ligament Reconstruction: A Retrospective Single-Center Analysis.

Background:Medial patellofemoral ligament reconstruction (MPFLR) is widely used to treat patellofemoral instability. However, it is still unclear when a concomitant bony procedure is needed.Purpose:To evaluate the therapeutic efficacy of isolated MPFLR for recurrent patellar lateral dislocation and to identify the prognostic factors for clinical outcomes.Study Design:Case series; Level of evidence, 4.Methods:A total of 237 patients who had undergone unilateral isolated MPFLR between January 2011 and December 2016 were included. Patellar tracking (J sign) and radiologic information including patellar height, trochlear dysplasia, tibial tubercle–trochlear groove distance, and patellar tilt was collected preoperatively, and the Kujala and International Knee Documentation Committee (IKDC) functional scores were used to assess postoperative recovery. Failure was defined as redislocation or patient-reported and clinically confirmed patellar instability. The influence of radiologic features and the J sign on knee functional scores was explored via subgroup analysis. Potential prognostic factors were explored using univariate and multivariate regression analyses, and risk factors for a positive J sign were evaluated using Spearman coefficient correlation analysis.Results:The mean ± SD follow-up period was 70.67 ± 18.05 months (range, 36-108 months). From preoperatively to final follow-up, all patients had statistically and clinically significant improvements in the Kujala score (from 51.43 ± 6.87 to 88.52 ± 4.83; P < .001) and IKDC score (from 49.78 ± 6.05 to 81.16 ± 4.20; P < .001). Subgroup analysis indicated no significant difference in functional score improvements based on radiologic features or the J sign. Overall, 20 knees (8.4%) experienced postoperative failure: 11 with redislocation and 9 with patellar instability. A preoperative positive J sign was shown to be an independent prognostic factor for postoperative failure via logistic regression analyses: univariate (odds ratio, 3.340; 95% CI, 1.316-8.480; P = .011) and multivariate (odds ratio, 3.038; 95% CI, 1.179-7.827; P = .021). In addition, the J sign was closely associated with patellar height (r S, 0.159; P = .014) and trochlear dysplasia (r S, 0.235; P < .001).Conclusion:Isolated MPFLR appears to be an effective strategy for recurrent patellar lateral dislocation, with significant functional improvement and a low failure rate. A preoperative positive J sign was identified as a potential prognostic risk factor for postoperative failure.

Surgical Management of Patella Alta in Patellofemoral Instability: A Systematic Review and Meta-analysis.

Background:Proximal, distal, and combined proximal and distal procedures have been performed for patellofemoral instability in the presence of patella alta. No consensus exists regarding the accepted surgical management for this condition.Purpose:To pool the outcomes of surgical management for patellofemoral instability in the presence of patella alta and to determine whether the outcomes differ for different surgical techniques.Study Design:Systematic review; Level of evidence, 4.Methods:This systematic review was conducted using the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. All studies that reported surgical outcomes for patellofemoral instability in the presence of patella alta were included. The random-effects model was used to analyze pooled estimates of preoperative and postoperative differences for outcomes that were reported in ≥3 studies. If heterogeneity existed among the studies, further analysis was performed using random-effects meta-regression analysis, which allowed for the identification of moderators.Results:A total of 11 studies with 546 knees were included. The pooled relative risk (RR) of having no patellofemoral dislocation and no patellofemoral apprehension or subjective instability postoperatively was 51.80 (95% CI, 20.75-129.31) and 48.70 (95% CI, 17.22-137.71), respectively. The pooled weighted mean improvement (WMI) for the Kujala and Lysholm scores postoperatively was 31.98 (95% CI, 28.66-35.30) and 35.93 (95% CI, 30.12-41.74), respectively. The pooled WMI for patellar tilt angles postoperatively was 10.94 (95% CI, 7.87-14.01). These outcomes were homogeneous across all studies. The pooled WMI for Insall-Salvati ratio, Caton-Deschamps index, and tibial tubercle–trochlear groove distance postoperatively was 0.31 (95% CI, 0.17-0.45), 0.24 (95% CI, 0.12-0.36), and 6.77 (95% CI, 1.96-11.58), respectively. These outcomes were heterogeneous across the studies, with the presence of distal procedures being a significant moderator. The presence of distal procedures had a significantly higher unweighted RR of 38.07 (95% CI, 2.37-613.09) for major complications compared with proximal procedures alone, although the incidence of minor complications was comparable (unweighted RR, 1.25; 95% CI, 0.35-4.48).Conclusion:Surgical management for patellofemoral instability in the presence of patella alta consistently led to improvement in clinical and functional outcomes, regardless of the type of procedure performed. Distal procedures were better able to correct the patellar height and tibial tubercle–trochlear groove distance, although these procedures also posed a higher RR of subsequent surgery compared with proximal procedures alone.

Changes in the Contact Stress Distribution Pattern of the Patellofemoral Joint After Medial Open-Wedge High Tibial Osteotomy: An Evaluation Using Computed Tomography Osteoabsorptiometry.

Background:Medial open-wedge high tibial osteotomy (OWHTO) theoretically causes distalization and lateralization of the tibial tuberosity and the patella.Purpose/Hypothesis:The purpose of the study was to identify any changes in the stress distribution of subchondral bone density across the patellofemoral (PF) joint before and after OWHTO through the use of computed tomography (CT) osteoabsorptiometry. We hypothesized that OWHTO would alter the distribution of contact stress in the PF joint.Study Design:Case series; Level of evidence, 4.Methods:A total of 17 patients (17 knees) who underwent OWHTO were enrolled in this study between September 2013 and September 2015. All patients underwent radiologic examination preoperatively and at 1 year postoperatively, and the distribution patterns of subchondral bone density through the articular surface of the femoral trochlea and patella were assessed preoperatively and >1 year postoperatively using CT osteoabsorptiometry. The quantitative analysis of the obtained mapping data focused on location of the high-density area (HDA) through the articular surface of the PF joint. The percentage of HDA at each divided region of the articular surface of the femoral trochlea and the patella was calculated.Results:In the radiologic evaluation, the Blackburne-Peel ratio was significantly reduced (P < .001) after surgery, and the tilting angle of the patella was significantly decreased (P < .001). On CT evaluation, the percentage of HDA in the lateral notch and lateral trochlea of the femur and in the medial portion of the lateral facet of the patella increased significantly after OWHTO surgery (P ≤ .038).Conclusion:OWHTO significantly increased the stress distribution pattern of the lateral trochlea of the femur and the medial portion of the lateral facet of the patella. The procedure significantly lowered the patellar height and significantly decreased the patellar tilting angle after surgery.

The patellofemoral joint does not deteriorate clinically after open-wedge high tibial osteotomy

BackgroundAfter high tibial osteotomy (HTO), the loading of the lateral compartment can be increased. Moreover, the change of patellar height may adversely affect the patellofemoral joint and functional outcomes. HypothesisWe hypothesized that the cartilage of the lateral compartment and patellofemoral joint would worsen after open-wedge HTO and the overcorrection of HTO could worsen the cartilage state of the patellofemoral joint. We evaluated the cartilage status and clinical results after medial open-wedge HTO and the factors affecting the outcomes. Materials and methodsFrom 2011 to 2018, 49 patients who had a mean age of 54.9 years and who underwent medial open-wedge HTO were selected. Plate removal was performed at a mean of 37.0 (range, 13–89) months after HTO, whereas diagnostic arthroscopy was performed during medial open-wedge HTO and plate removal. The cartilage status of each joint and the clinical results, including the Hospital for Special Surgery (HSS) score, Knee Society knee score (KS) and function score (FS), and patellar score, were compared. We evaluated the postoperative changes in the cartilage status and clinical scores. Additionally, we evaluated whether the postoperative correction degree could affect the clinical results. ResultAfter medial open-wedge HTO, the patellar height decreased. There was no change in the cartilage at the patellar and femoral trochlear groove. The HSS score, KS, and FS improved, but the patellar score remained unchanged. In the overcorrection group, the cartilage status significantly deteriorated at the lateral tibia condyle as compared with that in the undercorrection group. Higher preoperative clinical scores were associated with less postoperative improvement. Discussion and conclusionThe outcomes in the patellofemoral joint, including the cartilage condition and clinical scores, did not change after open-wedge HTO, despite patellar infera. Additionally, they were not influenced by the correction degree. Higher preoperative clinical scores were associated with less postoperative improvement. Level of evidenceIV; retrospective study.

The Blackburne–Peel Index for Determining Patellar Height Is Affected by Tibial Slope

PurposeTo establish a quantitative relationship between the Blackburne–Peel index and posterior tibial slope in both skeletally mature and skeletally immature individuals and to evaluate the rate at which variation in tibial slope influences changes in patellar height categorization as normal, patella alta, and patella baja.MethodsA consecutive series of lateral knee radiographs were retrospectively reviewed. Radiographs were excluded for rotation, inadequate visible proximal tibia length, and obstructive hardware/pathology. Modified tibial slopes of 0°, 5°, 10°, and 15° were projected anteriorly from the medial tibial plateau as described by Blackburne–Peel. The Blackburne–Peel index was determined at each modified tibial slope interval. Caton–Deschamps and Insall–Salvati indices also were measured for comparison. The rate of Blackburne–Peel index change with increase in posterior tibial slope was quantitatively analyzed.ResultsFifty skeletally mature and 50 skeletally immature radiographs were included. In the skeletally mature, Blackburne–Peel indices decreased on average by 0.037, 0.044, and 0.049 as posterior tibial slope increased from 0-5°, 5-10°, and 10-15°, respectively. In the skeletally immature, Blackburne–Peel indices decreased on average by 0.045, 0.053, and 0.059 as posterior tibial slope increased from 0-5°, 5-10°, and 10-15°, respectively. Overall, 29 individuals with 0° of tibial slope were categorized as patella alta by the Blackburne–Peel index, and only 16 (55%) remained categorized as patella alta after increasing their posterior tibial slope to 15°.ConclusionsThis study quantitatively demonstrates the relationship between posterior tibial slope and the Blackburne–Peel index. As expected, as posterior tibial slope increases, the Blackburne–Peel index decreases. While the change in the Blackburne–Peel index per 5° change in tibial slope appears to be small, nearly half (45%) of individuals categorized as patella alta with 0° of tibial slope were categorized as normal when their posterior tibial slope was systematically increased from 0° to 15°. When evaluating patellar height, it is important to understand how tibial slope affects the Blackburne-Peel Index measurement.Clinical RelevanceAs posterior tibial slope increases, the numerator of the Blackburne-Peel ratio decreases, and vice versa. This relationship can lead to incorrect assessment of patellar height. Objectively placing individuals into patella alta and baja categories may influence patient care and decision making.

Proximal tibial osteotomy for genu varum: Radiological evaluation of deformity correction with a plate vs external fixator

BACKGROUNDHigh tibial osteotomy (HTO) is a well-known procedure for the correction of knee varus. The purpose of this study was to compare the radiological results and accuracy of deformity correction performed using two different techniques: acute opening wedge correction using a plate and gradual correction with a monolateral external fixator.AIMTo compare of the radiological results of two different techniques: acute opening wedge correction (a plate and screw) and gradual correction (external fixator).METHODSA total of 43 patients with plates and 36 patients with external fixators were included. All patients had moderate uniplanar varus deformities. We measured radiographic parameters, including the mechanical axis deviation (MAD), medial proximal tibial angle (MPTA), Caton-Deschamps Index (CDI), posterior proximal tibial angle, and joint line obliquity angle (JLOA). The accuracy of MAD correction was calculated based on a correction goal of neutral or overcorrection for medial compartment arthritis.RESULTSDemographics including age, body mass index, sex, and preoperative deformities were similar between the groups. The MAD significantly improved from 23.6 mm medial to the midline (SD = 8.2 mm) to 6.9 mm lateral to the midline (SD = 5.4 mm) (P < 0.001). The accuracy of MAD correction did not differ between the groups and was 96.1% (SD = 8.1%) in the plate group and 98.2% (SD = 5.2%) in the external fixator group (P = 0.18). The MPTA significantly improved from 83.9° (SD = 2.9°) to 90.9° (SD = 3.3°) (P < 0.001), and the change was similar between the groups. Differences were noted in patella height, with a CDI change of -19.2% (SD = 13.7%) and 3.1% (SD = 8.0%) for the plate and external fixator groups, respectively (P < 0.001). The change in JLOA was 1.6 degrees (SD = 1.1 degrees) and 0.9 degrees (SD = 0.9 degrees) for the plate and external fixator groups, respectively (P = 0.04).CONCLUSIONReliable correction of moderate varus alignment was achieved with both the acute opening wedge technique with a plate and the gradual monolateral external fixator technique. The patellar height decreased with the open wedge plate technique. Joint line obliquity decreased to a greater degree with the open wedge plate technique, perhaps as a result of medial collateral ligament release. The appropriate technique should be selected based on surgeon and patient preferences; however, external fixation may be a better choice when the preservation of patellar height is deemed important.

Retro-Tubercle Biplanar Opening Wedge High Tibial Osteotomy Is Favorable for the Patellofemoral Joint But Not for the Osteotomized Tubercle Itself Compared With Supra-Tubercle Osteotomy

To identify whether retro-tubercle opening-wedge high tibial osteotomy (RT-OWHTO) produces more favorable radiographic outcomes on patellofemoral joint alignment and clinical outcomes than supra-tubercle opening-wedge high tibial osteotomy (ST-OWHTO). From January 2017 to July 2018, patients who underwent biplanar OWHTO were allocated to 1 of 2 groups (ST-OWHTO and RT-OWHTO). Plain radiographs and computed tomography were used to analyze patellofemoral alignment and other radiologic parameters representing osteotomy configurations. Clinical outcomes were assessed using American Knee Society Score and Western Ontario and McMaster Universities Osteoarthritis Index. In total, 50 knees that underwent ST-OWHTO and 44 knees that underwent RT-OWHTO were enrolled. Patellar height was significantly decreased only after ST-OWHTO (Caton-Deschamps ratio: P= .007; Blackburne-Peel ratio: P= .012). Patellar tilt angle was decreased in both groups (P= .009 and .004, respectively). Postoperative posterior tibial slope (PTS) (P= .013), PTS (Δ) (P < .001), retro-tuberosity gap distance (P= .001), and retro-tuberosity tip distance (P= .001) were significantly larger in RT-OWHTO. Retro-tuberosity tip distance was significantly correlated with retro-tuberosity gap distance (P= .002), thickness of second plane osteotomy fragment (P=.027), and anterior osteotomy ratio (P= .031) in ST-OWHTO. In RT-OWHTO, it was significantly correlated with PTS (△) (P < .001), retro-tuberosity gap distance (P < .001), and sagittal angle of bi-planar osteotomy (P= .005). There were 2 cases of tibial tuberosity fracture, 9 cases of delayed union on second plane osteotomy and 5 cases of tuberosity protrusion in RT-OWHTO. Although the RT-OWHTO technique maintains patellofemoral joint alignment, no difference in clinical outcome was detected. The RT-OWHTO has increased risk of tuberosity fracture, delayed union, and prominent tibial tuberosity. The surgeon should consider these negative aspects of the technique and consider adjusting additional stabilization. Level III, retrospective cohort study.

Treatment of acquired patella baja by proximalization tibial tubercle osteotomy significantly improved knee joint function but overall patient-reported outcome measures remain diminished after two to four years of follow-up

Acquired patella baja is often characterized by painful limitation of knee joint range of motion and anterior knee pain (AKP). Only few studies have evaluated the effectiveness of surgical treatment in terms of patient-reported outcome measures (PROM's) and sports activity. Thus, the goal of this study was to assess PROM's and sports activity after proximalization tibial tubercle osteotomy (P-TTO) in patients with symptomatic patella baja. Between 2016 and 2018, a case series of 11 patients (male/female 4/7; age 48 ± 12years) were treated by P-TTO and were retrospectively evaluated after a mean of 33.7months (range 24-51months). The Tegner activity score and the Kujala anterior knee pain scale were used in addition to a visual analogue scale (VAS; 0-10) regarding self-reported knee joint function and intensity of AKP. Radiographic assessment included the measure of patellar height using the Caton-Deschamps (CD) and Blackburne-Peel (BP) index. Postoperatively both the CD and the BP index increased to normality (p < 0.0001; p = 0.0012). Knee joint flexion improved from 100 ± 32° preoperatively to 123 ± 14° postoperatively (p = 0.0235). AKP decreased from 6.5 ± 2.1 points preoperatively to 3.7 ± 2.1 points postoperatively (p = 0.0061). This was accompanied by a significant increase in self-reported knee joint function from 1.8 ± 1.2 points preoperatively to 6.8 ± 2.3 points postoperatively (p = 0.0001) and an increase of the Tegner activity score from 1.8 ± 1.6 points preoperatively to 3.9 ± 1.5 points postoperatively (p = 0.0074). Although the Kujala score improved significantly by an average of 31.55 points (p = 0.001) overall score results remained reduced at 65.6 ± 17.9 points at final follow-up. P-TTO yielded significant improvements in terms of AKP, subjective knee joint function and sports activity. However, the overall Kujala score results remained reduced, indicating that surgical correction of patellar height is not sufficient to relieve all patients' complaints. In addition, the incidence of postoperative complications was high.

High tibial osteotomy to neutral alignment improves medial knee articular cartilage composition.

The purpose of this study was to: (1) test the hypothesis that HTO improves articular cartilage composition in the medial compartment without adversely affecting the lateral compartment and patella, and; (2) explore associations between knee alignment and cartilage composition after surgery. 3T MRI and standing radiographs were obtained from 34 patients before and 1-year after HTO. Articular cartilage was segmented from T2 maps. Mechanical axis angle (MAA), posterior tibial slope, and patellar height were measured from radiographs. Changes in T2 and radiographic measures were assessed using paired t tests, and associations were assessed using Pearson correlation coefficients. The mean (SD) MAA before and after HTO was - 6.5° (2.4) and 0.6° (3.0), respectively. There was statistically significant shortening [mean (95%CI)] of T2 in the medial femur [- 2.8ms (- 4.2; - 1.3), p < 0.001] and medial tibia [- 2.2ms (- 3.3; - 1.0), p < 0.001], without changes in the lateral femur [- 0.5ms (- 1.6; 0.6), p = 0.3], lateral tibia [0.2ms (- 0.8; 1.1), p = NS], or patella [0.5ms (- 1.0; 2.1), p = NS). Associations between radiographic measures and T2 were low. 23% of the increase in lateral femur T2 was explained by postoperative posterior tibial slope (r = 0.48). Performing medial opening wedge HTO without overcorrection improves articular cartilage composition in the medial compartment of the knee without compromising the lateral compartment or the patella. Although further research is required, these results suggest HTO is a disease structure-modifying treatment for knee OA.

Primary total knee arthroplasty in tibial plateau fractures: Literature review and our institutional experience

BackgroundDisplaced proximal tibia fractures in the elderly may be very difficult to manage. If osteosynthesis represents the standard of care in the younger patients, in the aged population this solution is controversial because a significant failure rate has been reported after internal fixation. Moreover, osteoarthritis progression following tibial plateau fractures is common, often requiring a subsequent total knee arthroplasty (TKA). In recent years, in order to overcome the fracture healing problems and to allow immediate full weight bearing, primary TKA after tibial plateau fractures in elderly patients has gained popularity. Material and methodsfrom 2015 to 2019, 11 tibial plateau fractures in elderly patients with pre-existing osteoarthritis were treated with a primary TKA. Age, gender, mechanism of trauma, pre-operative autonomy level, fractures classification, degree of osteoarthritis and intraoperative data (ligamentous stability and type of implant) were collected. After a mean follow-up of 28 months, Knee Society Score (KSS), post-operative autonomy level and Forgotten Joint Score (FJS) were evaluated. The radiological assessment (signs of loosening, limb axis and patellar height indices) and complications were also recorded. Resultsaccording to fracture type and ligamentous competence, 6 cases of posterior-stabilized (PS) design and 5 cases of semi-constrained TKA were implanted. At the final follow up, mean KSS knee score was 83±16 and mean KSS functional score was 74±15. Mean pre-operative autonomy level assessed with the Parker scale, was significantly higher than the post-operative one (7.5±1.4 vs 5.6 ± 1.3). Mean FJS was 66 ± 14. No lines of radiolucency or limb malalignment were found at the final radiological follow-up. One major complication was recorded: one acute periprosthetic infection. One patient reported a periprosthetic femoral fracture after 26 months. ConclusionBased on our and results and those reported on literature, primary TKA is a suitable option in case of tibial plateau fractures in elderly patients with pre-existing osteoarthritis and poor bone quality, in which osteosynthesis outcome may be poor. Unlike ORIF, primary TKA may allow immediate weightbearing and a faster recovery. Nevertheless, it is a demanding surgery with a significant complications rate and should be reserved for selected patients and experienced surgeons.

Factors related to the early outcome of medial open wedge high tibial osteotomy: coronal limb alignment affects more than cartilage degeneration state

This study aimed to identify possible factors influencing the early outcome after medial open wedge high tibial osteotomy (MOWHTO). A total of 87 MOWHTO cases with a minimum of 2-year follow-up and second-look arthroscopic results available were enrolled. The cartilage degeneration state was evaluated by the International Cartilage Repair Society (ICRS) grading. Radiographic parameters including the hip-knee-ankle axis (HKA), medial proximal tibia angle (MPTA), posterior tibial slope, patellar height, mechanical lateral distal femoral angle (LDFA), joint line convergence angle (JLCA), joint line obliquity (JLO), and weight-bearing line ratio (WBLR) were measured. The pre-operative arthritic change was evaluated by Kellgren-Lawrence (KL) classification. According to the post-operative HKA, knees were divided into three (Under/Optimal/Over-correction) subgroups. Subjective International Knee Documentation Committee (IKDC) scores were evaluated and factors related to post-operative IKDC scores were analyzed. The pre-operative HKA (P = 0.002), post-operative HKA (P = 0.007), pre-operative MPTA (P = 0.011), and pre-operative WBLR (P = 0.031) were significantly related to the post-operative IKDC score. Cartilage degeneration states evaluated from first and second-look arthroscopy were not associated with post-operative IKDC score. Subgroup analysis revealed that the Under-correction group had significantly lower post-operative IKDC scores compared to the Optimal and Over-correction group (P = 0.012 and P = 0.030, respectively). Our result suggests that a sub-optimal correction of coronal limb alignment negatively affects the early outcome of MOWHTO. On the other hand, the effect of the degree of cartilage degeneration was not significant.

Reliability of a Caton-Deschamps-derived patella height index for knee arthroplasty

PurposeThe original Caton-Deschamps index (oCDI) detects functional patella height. It cannot be used in knees with an implanted endoprosthesis. The “modified Caton-Deschamps index” (mCDI) for knee arthroplasty can miss pseudo-patella-infera (PPI), which is common after TKA. A derivate of the oCDI could be a simple analogue to the index published in 1982 using a modified tibial reference point at the anterior proximal point of the inlay, which can indirectly be located on the lateral knee radiograph. It was the aim of this study to determine the intra- and inter-rater agreement of a derived Caton-Deschamps index (dCDI) for knee arthroplasty. We hypothesized that the derived Caton-Deschamps index (dCDI) is a reliable radiological measure for patella height in knee arthroplasty.MethodsSeveral patella height indices were measured by three independent raters in two passes. The second pass was performed after 6 weeks in random order. Intra- and inter-observer agreements were determined and analyzed using the intraclass correlation coefficient (ICC). For radiographic evaluation, digital lateral radiographs of 150 knees before and after primary TKA were used.ResultsWe found high interrater reliability for all analyzed indices. We found the highest agreements for the ISI preop (ICC = 0.914) and postop (ICC = 0.920), respectively. We also found very good intra-rater reliability for the CDI (ICCpreop = 0.954), dCDI (ICCpostop = 0.945), ISI (ICCpreop = 0.960; ICCpostop=0.940) and BPI (ICCpreop = 0.969; ICCpostop = 0.955). Fourteen cases (9.3%) with insignificant PPI were found.ConclusionThe derived Caton-Deschamps index (dCDI) can easily be used in knee arthroplasty and demonstrated high intra- and interrater agreement, which was similar to other commonly used and established patella height indices.

Complete Removal of the Infrapatellar Fat Pad in Total Knee Arthroplasty Does Not Affect the Patellar Height

Complete Removal of the Infrapatellar Fat Pad in Total Knee Arthroplasty Does Not Affect the Patellar Height