Blackburne-Peel Index Research Articles

Can double-level osteotomy prevent patellofemoral osteoarthritis progression compared with open wedge high tibial osteotomy?

To compare radiographic, clinical, and arthroscopic findings in patellofemoral (PF) osteoarthritis (OA) between open wedge high tibial osteotomy (OWHTO) and double-level osteotomy (DLO) with the same operative indication. After adjustment for patient age, and coronal alignment, 36 knees with OWHTO alone and 36 knees with DLO were compared. Radiographic, clinical, and arthroscopic findings were documented before osteotomy. Arthroscopic findings were observed 1year after osteotomy, and clinical and radiographic findings were observed 2years after osteotomy. Patellar height was evaluated using the Insall-Salvati (IS) ratio, Carton-Deschamps (CD) index, and Blackburne-Peel (BP) index. Lateral patellar tilt and patellar shift were measured. A power analysis was performed. The postoperative CD and BP indices in the OWHTO group were lower than those in the DLO group (p < 0.001 and p = 0.001, respectively). The CD and BP indices in both groups significantly decreased postoperatively (all p < 0.001). Tilting angles in the OWHTO and DLO groups significantly decreased postoperatively (p < 0.001 and p = 0.002, respectively). There were no significant differences in American Knee Society scores, Kujala score, and the Knee Injury and Osteoarthritis Outcome Scores between both groups. The PF OA progression of the trochlear in the OWHTO group was higher than that in the DLO group (p = 0.002), and the PF OA progression of the patellar facet in the DLO group and anterior femoral condyle in both groups on the lateral side were higher than those on the medial side (p = 0.006, 0.032, and 0.041, respectively). DLO decreased the rate of low patellar height compared with OWHTO. DLO decreased the rate of PF OA progression in the trochlea compared with OWHTO. There were no significant differences in clinical outcomes in both groups. Level III, case-control study.

Assessment of the reliability and validity of imaging measurements for patellofemoral instability: an updated systematic review.

To provide an update on the reliability and validity of all radiological measures used to assess patients presenting with patellofemoral instability. A search of the CINHAL, EMBASE, MEDLINE, and SCOPUS databases and the Cochrane library was conducted. All studies assessing the validity, reliability, sensitivity, and specificity of radiological measures of the patellofemoral joints of patients with patellofemoral instability from 2010 onwards were considered for inclusion. Discrimination validity, inter- and intra-observer reliability, and the sensitivity and specificity of specific imaging measures were evaluated. Seventy-three studies met the selection criteria and were included for analysis. We identified eight radiological measures in four categories with good reliability and validity: the tibial tubercle to trochlear groove distance, specific measures of patellar height (Blackburne-Peel index, Caton-Deschamps index and Insall-Salvati ratios), three measures of trochlear dysplasia (sulcus angle, trochlear depth, and lateral trochlear inclination), and the tibial tubercle to posterior cruciate ligament distance. No included studies examined the reliability and validity of patellofemoral instability ultrasound measures. Our updated review demonstrated good inter- and intra-observer reliability and discrimination validity for the tibial tubercle-trochlear groove distance, specific patellar height, and trochlear dysplasia measures on MRI. The tibial tubercle to posterior cruciate ligament distance, an indirect measure of rotational asymmetry, was a valid and reliable measure on MRI. Due to a lack of assessments across more than one study, there are a variety of proposed measures with insufficient evidence to determine their validity, reliability, sensitivity, and specificity.

Distal tibial tubercle osteotomy can lessen change in patellar height post medial opening wedge high tibial osteotomy? A systematic review and meta-analysis

ObjectiveMedial opening wedge high tibial osteotomy (MOWHTO) is a mainstream surgical method for treating early medial compartment knee osteoarthritis. Undesirable sequelae such as patella infera may happen following tuberosity osteotomy. We conducted this systematic review and meta-analysis to compare the change in patellar position after proximal tibial tubercle osteotomy (PTO) versus distal tibial tubercle osteotomy (DTO) intervention.MethodsThe 11 studies were acquired from PubMed, Medline, Embase and Cochrane Library. The data were extracted by two of the coauthors independently and were analyzed by RevMan5.3. Mean differences, odds ratios and 95% confidence intervals were calculated. Cochrane Collaboration’s Risk of Bias Tool and Newcastle–Ottawa Scale were used to assess risk of bias.ResultsEleven observational studies were assessed. The methodological quality of the trials ranged from moderate to high. The pooled results of postoperative patellar height (Caton-Deschamps index and Blackburne-Peel index) and postoperative complications showed that the differences were statistically significant between PTO and DTO interventions. Patellar index ratios decreased significantly in the PTO groups, and 12 (9.2%) complications under DTO surgery and 2 (1.6%) complications under PTO surgery were reported. The differences of postoperative posterior tibial slope (angle) was not statistically significant, but postoperative posterior tibial slope of both groups increased. Sensitivity analysis proved the stability of the pooled results and the publication bias was not apparent.ConclusionsDTO in MOWHTO maintained the postoperative patellar height, and clinically, for patients with serious patellofemoral osteoarthritis, DTO can be preferred. Postoperative complications are easily preventable with caution. In view of the heterogeneity and small sample size, whether these conclusions are applicable should be further determined in future studies.

The Dynamic Effect of Anterior Cruciate Ligament Deficiency on Patellar Height.

The anterior tibial translation (ATT) in case of Anterior Cruciate Ligament (ACL) tear can lead to dynamic alterations of the extensor apparatus biomechanics. The aim of this study is to evaluate the dynamic effect of isolated ACL deficiency on patellar height. The hypothesis is that the ATT of ACL-insufficient knees dynamically reduces patellar height. Skeletally mature patients who underwent ACL reconstruction using hamstring graft between January and December 2018 were included in this study.The Posterior Tibial Slope (PTS), Caton-Deschamps (CDI), modified Insall-Salvati (MISI), and Blackburne-Peel (BPI) indices were calculated in standard lateral and TELOS X-rays. The mean of the measurements calculated between two observers was used to compare these parameters. 95 patients (M: 57; F: 38; 95 knees) were included in the study with a mean age of 31.8years (16-56years old). Significant patellar height reduction (CDI: 0.11 [-0.32; 0.31]; MISI: 0.09 [-0.66; 0.30]) was reported in TELOS compared with standard lateral knee radiography (p < 0.001). 20.0% of the study knees reported an abnormal CDI and 84.2% (16/19 knees) of them reduced this index to within normal limits in TELOS. 20.0% of the knees with mild patella alta reduced CDI in TELOS but always remained above 1.2. The abnormal ATT in case of ACL-deficient knees results in a lowering effect of the patella in TELOS X-rays. In patients with ACL tear and anterior pain the reconstructive ligament surgery should be performed to avoid also chronic anterior knee pain. Basic Science Study (Case Series). The decrease in patellar height in stress-X-rays compared with standard lateral knee radiography in ACL deficient knees, should be considered as a possible contributing cause of anterior pain in these patients.

Postoperative Patellar Height After Undergoing Total Knee Arthroplasty: Mechanical Axis Versus Kinematic Axis.

IntroductionWhen performing total knee arthroplasty (TKA), surgeons may use either the mechanical alignment (MA) or the kinematic alignment (KA) to guide implant placement and joint balancing. By measuring preoperative and postoperative patellar height (PH), surgeons can predict knee stability after TKA. Improper PH is associated with knee instability which may complicate the postoperative course and lead to patient dissatisfaction or need for revision. The purpose of this study is to measure patellar height using the Insall-Salvati Index (ISI), Caton-Deschamps Index (CDI), and Blackburne-Peel Index (BPI) preoperatively and postoperatively in patients who underwent TKA with either MA or KA to assess for changes in patellar height.MethodsWe performed a retrospective eight-year review of 256 patients who underwent TKA with either MA or KA by a single surgeon at a single hospital site. We obtained demographic data, including gender, age, and BMI, via the electronic health record. Furthermore, we calculated the ISI, CDI, and BPI using necessary parameters from preoperative and postoperative radiographs. We used these measurements to assess any statistically significant difference in postoperative PH.ResultsThe MA cohort consisted of 104 patients with an average age of 63 years and an average BMI of 34.1 kg/m2. The KA cohort included 152 patients with an average age of 64 years and an average BMI of 34.9 kg/m2. For the MA population, the average postoperative score with ISI was 1.10 [1.05 to 1.16] (p < 0.001), with CDI was 1.05 [0.98 to 1.11] (p < 0.001), and with BPI was was 0.94 [0.89 to 0.99] (p < 0.001). While for the KA population, the average postoperative score with ISI was 1.03 [0.99 to 1.06] (p = 0.17), with CDI was 0.87 [0.82 to 0.91] (p = 0.15), and with BPI was 0.82 [0.78 to 0.86] (p = 0.34).ConclusionTKA with a KA has a statistically significant improvement in postoperative PH and better postoperative maintenance of preoperative PH. Improved PH may lead to increased patellofemoral stability and superior postoperative outcomes in patients undergoing TKA. Future studies should focus on whether differences in preoperative and postoperative PH measurements result in changes in clinical outcomes in patients with MA versus KA TKA.

Similar outcomes including maximum knee flexion between mobile bearing condylar-stabilised and fixed bearing posterior-stabilised prosthesis: a case control study

PurposeProsthesis design influences stability in total knee arthroplasty and may affect maximum knee flexion. Posterior-stabilised (PS) and condylar-stabilised (CS) designed prosthesis do not require a posterior-cruciate ligament to provide stability. The aim of the current study was to compare the range of motion (ROM) and clinical outcomes of patients undergoing cemented total knee arthroplasty (TKA) using either a PS or CS design prosthesis.MethodsA total of 167 consecutive primary TKAs with a CS bearing (mobile deep-dish polyethylene) were retrospectively identified and compared to 332 primary TKA with a PS constraint, with similar design components from the same manufacturer. Passive ROM was assessed at last follow-up with use of a handheld goniometer. Clinical scores were assessed using Patient-Reported Outcome Measures (PROMs); International Knee Society (IKS) knee and function scores and satisfaction score. Radiographic assessment was performed pre and post operatively consisting of mechanical femorotibial angle (mFTA), femoral and tibial mechanical angles measured medially (FMA and TMA, respectively) on long leg radiographs, tibial slope and patella height as measured by the Blackburne-Peel index (BPI).ResultsBoth groups had a mean follow-up of 3 years (range 2–3.7 years). Mean post-operative maximum knee flexion was 117° ± 4.9° in the PS group and 119° ± 5.2° in the CS group (p = 0.29). Postoperative IKS scores were significantly improved in both groups compared to preoperative scores (p < 0.01). The mean IKS score in the PS group was 170.9 ± 24.1 compared to 170.3 ± 22.5 in the CS group (p = 0.3). Both groups had similar radiographic outcomes as determined by coronal and sagittal alignment, tibial slope and posterior condylar offset ratio measurements. When considering the size of tibial slope change and posterior-condylar offset ratio, there was no differences between groups (p = 0.4 and 0.59 respectively). The PS group had more interventions for post-operative stiffness (arthrolysis or manipulation under anaesthesia) 8 (2.7%) compared to 1 (0.6%) in the CS group (p = 0.17).ConclusionCondylar-stabilised TKA have similar patient outcomes and ROM at a mean follow-up of 3 years compared to PS TKA. Highly congruent inserts could be used without compromising results in TKA at short term.Level of evidenceLevel IV, retrospective case control study.

Patellar Height after High Tibial Osteotomy of the Distal Tibial Tuberosity: A Retrospective Study of Age Stratification.

Objective To explore the effect of age stratification on patellar height after single-plane high tibial osteotomy of the distal tibial tuberosity (DTT-HTO). Methods A retrospective analysis was performed on 110 knee joints undergoing DTT-HTO. Patients were divided into three groups according to age: under 60 years old, 28 cases; 60 to 70 years old, 61 cases; and over 70 years old, 21 cases. All patients were followed up for no less than 12 months, and at each follow-up, short-leg radiographs and whole-leg radiographs were taken. The values of the Caton-Deschamps index (CDI) and Blackburne-Peel index (BPI) of single-short-leg radiographs and the femoral-tibial angle (FTA) and weight-bearing line ratio (WBLR) of whole-leg radiographs were measured before and at the last follow-up. The Lysholm score before and at the last follow-up and the visual analogue scale (VAS) score before and 3 days after surgery and at the last follow-up were calculated. The frequency of classification of the normal-height patella, patella alta, and patella baja before and after surgery was recorded. Results There were no significant differences in CDI and BPI preoperatively or postoperatively among the three groups (P > 0.05), and there were no statistically significant differences in FTA and WBLR. There were no significant differences in CDI, BPI, FTA, or WBLR between the three groups before and after the operation (P > 0.05). The Lysholm score increased from 48.84 ± 10.10 before surgery to 91.96 ± 3.082 after surgery (P < 0.05); the VAS score decreased from 8.23 ± 0.99 before surgery to 1.93 ± 0.953 at 3 days after surgery and 1.07 ± 0.53 at the last follow-up (P < 0.01). No significant difference was observed in the incidence of each patellar height classification between the three groups preoperatively and postoperatively. Conclusion Patellar height is not influenced by DTT-HTO. The age of patients is not a limiting factor for the selection of this surgical procedure. Without affecting the height of the patella, DTT-HTO can effectively reduce pain in the knee joint, restore the function of the knee joint, and delay the progression of patellar arthritis.

Comparison of two osteotomies in the treatment of medial compartment osteoarthritis

To compare the effectiveness of modified distal tibial tubercle-high tibial osteotomy (DTT-HTO) and open-wedge HTO (OWHTO) in the treatment of medial compartment osteoarthritis. A clinical data of 80 patients with medial compartment osteoarthritis treated with HTO between January 2016 and January 2019 was retrospectively analyzed, including 40 patients treated with DTT-HTO (DTT-HTO group) and 40 patients treated with OWHTO (OWHTO group). There was no significant difference in gender, age, body mass index, affected side, disease duration, Kellgren-Lawrence grading of osteoarthritis, and preoperative knee society score (KSS), Hospital for Special Surgery (HSS) score, knee joint visual analogue scale (VAS) score, hip-knee-ankle angle (HKA), posterior tibial slope (PTS), weight-bearing line ratio (WBL), Blackburne-Peel index (BPI), Caton-Deschamps index (CDI), and Insall-Salvati index (ISI) between the two groups ( P>0.05). The operation time, incision length, bleeding volume, hospital stay, and complications in both groups were recorded. The KSS, HSS, and VAS scores were used to evaluated the effectiveness. A self-made questionnaire was used to evaluate the recovery of low-impact sports ability of the knee. X-ray films were used to observe the osteotomy healing and measure the HKA, PTS, WBL, and the patellar height indexes (BPI, CDI, ISI). All operations successfully completed in both groups. The OWHTO group operated longer than the DTT-HTO group ( P<0.05). There was no significant difference in the incision length, bleeding volume, and hospital stay between the two groups ( P>0.05). All incisions healed by first intention in both groups. There were 2 cases of lateral hinge fractures in the OWHTO group, and 1 case of lateral hinge fracture and 2 cases of tibial plateau fractures in the DTT-HTO group. No other complications occurred. The patients in both groups were followed up 2-4 years with an average of 2.8 years. The HSS, KSS, and VAS scores in both groups significantly improved after operation when compared with preoperative scores ( P<0.05). All scores gradually improved with the time and there were significant differences between different time points ( P<0.05). The HSS, KSS, and VAS scores were significantly better in the DTT-HTO group than in the OWHTO group at 3 months after operation ( P<0.05). There was no significant difference between the two groups at 6 months, 1 year, and 2 years ( P>0.05). At 1 year, the low-impact sports ability of the OWHTO group was rated as excellent in 8 cases, general in 25 cases, and poor in 7 cases, and as excellent in 7 cases, general in 26 cases, and poor in 7 cases of the DTT-HTO group. There was no significant difference between the two groups ( Z=-0.715, P=0.475). X-ray film reexamination showed that the osteotomies healed in both groups. The healing time was (4.52±1.23) months in the OWHTO group, and (4.23±1.56) months in the DTT-HTO group, showing no significant difference ( t=0.923, P=0.359). At immediate after operation, the HKA and WBL of the two groups significantly improved when compared with the preoperative values ( P<0.05). However, the pre- and post-operational difference was not significant between the two groups ( P>0.05). The PTS of the OWHTO group was significantly higher than preoperative value ( P<0.05), while the PTS of the DTT-HTO group was lower than preoperative value ( P>0.05). The pre- and post-operational difference between the two groups was significant ( P<0.05). BPI and CDI in the OWHTO group were significantly lower than preoperative values ( P<0.05), but there was no significant difference in ISI when compared with preoperative value ( P>0.05). There was no significant difference in the BPI, CDI, and ISI of the DTT-HTO group between pre- and post-operation ( P>0.05). The pre- and post-operational differences of BPI and CDI between the two groups were significant ( P<0.05), and there was no significant difference in the pre- and post-operational difference of ISI ( P>0.05). The two osteotomies in the treatment of medial compartment osteoarthritis can significantly change the varus deformity and achieve satisfactory effectiveness. The early functional recovery of DTT-HTO is faster, which can avoid the increased PTS and patellar baja of traditional OWHTO. However, neither of the two surgical procedures can restore the patient's ideal low-impact sports ability of the knee.

Pseudo-patella baja after total knee arthroplasty: Radiological evaluation and clinical repercussion

BackgroundAnterior knee pain is an important complication after total knee arthroplasty (TKA). One possible contributor is the elevation of the joint line, known as pseudo-patella baja (PPB). Limited research has been conducted regarding this condition impacting TKA management. This study aims to evaluate the incidence, identify possible related factors and assess PPB clinical repercussions. MethodsA total of 813 consecutive TKAs were retrospectively reviewed. Patients were submitted to the same surgical procedure and information regarding TKA characteristics was collected. Lateral postoperative knee radiographs were analyzed using the modified Insall–Salvati Ratio and the Blackburne–Peel Index. A clinical evaluation was conducted on 112 knees where the Oxford Knee and Kujala Scores were applied. Range of motion was evaluated, and knee pain was assessed using the numeric pain rating scale, in addition to analgesic consumption. ResultsA cohort of 612 knees was analyzed, of which 64 knees developed PPB (10.5% incidence). Statistically significant differences were found for advance components sizes (femoral P = 0.026 and tibial P < 0.001), polyethylene thickness (P < 0.001) and patients’ height (P = 0.022) with smaller implant sizes, greater insert thicknesses and lower height showing an association with PPB. The PPB group had a significantly lower median Kujala score (P = 0.011), higher frequency of flexion contracture and of anterior knee pain (P = 0.039). ConclusionPPB has a clinical relevance that should not be overlooked. Its prevention through the recreation of the natural position of the joint line and correct choice of implant sizes and polyethylene thickness is of major importance and should always be considered.

Effect of the amount of correction on posterior tibial slope and patellar height in open-wedge high tibial osteotomy.

Objectives: To evaluate the effect of amount of correction on postoperative changes in PTS (posterior tibial slope), PH (patellar height), and clinical outcomes following biplanar OWHTO (open-wedge high tibial osteotomy). Method: This study included 79 knees (32 left and 47 right) of 79 patients (mean age 60.28 ± 4.2years, 24 males, 55 females) with varus malalignment and symptomatic isolated medial joint osteoarthritis who underwent OWHTO. According to the amount of correction angles, all patients were divided into three groups: LCA (large correction angle) group (>14°), MCA (medium correction angle) group (10°-14°), and SCA (small correction angle) group (<10°). All patients were clinically assessed according to the Lysholm score, HSS (hospital for special surgery knee score), and KSS (knee society score) prior to and after surgery. For radiographic analysis, we measured the PTS, PH [ISI (Insall-Salvati index), and BPI (Blackburne-Peel index)]. The pre-post difference of PTS, ISI, and BPI was calculated by subtracting the post-OWHTO value to the pre-OWHTO value in three groups, respectively. The preoperative, postoperative, and difference of PTS, ISI, and BPI values were analyzed according to the correction angle. The mean follow-up period was 28.5months (SD, 4.9; range 18-52months). Results: Radiologically, PTS increased and PH decreased after surgery on the whole (p < .05). The relationship between amount of correction and slope increase is significant (p < .001). Furthermore, the pairwise difference between the LCA group and SCA group and MCA group is significant respectively (p < .05). In terms of PH, the LCA group yielded ISI and BPI that were significantly different from baseline for the SCA group and MCA group. In addition, the pairwise difference between the SCA group and LCA group in ISI and BPI is significant (p = .031). Clinically, significant improvements were observed in postoperative clinical scores of the Lysholm score, HSS, and KSS (p < .05). Seventy-four patients (93.67%) reported satisfaction with surgery. However, no correlation was found between changes in PTS and PH with postoperative knee score. No severe adverse complications were observed. Conclusions: The amount of correction angle is a significant factor affecting the PTS and PH in OWHTO. With increased correction angle, the likelihood of increasing the PTS and decreasing the PH increases. Special attention should be paid to keep PTS and PH unchanged in cases where large corrections are required. Otherwise, closing wedge osteotomy or other intraoperative effective measures are supposed to be adopted.

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

PurposeIdentifying 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.MethodsFifty-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.ResultsForty 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.ConclusionAnatomical, 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 evidenceLevel IV

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.

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.

A new method for evaluation of patellar height and the position of the joint line before and after total knee arthroplasty

BackgroundThe measurement of patellar height and restoration of the natural position of the joint line are crucial to total knee arthroplasty (TKA). However, there remains a lack of consensus on an optimal measurement method to associate the patellar height with the joint line position. The objective of this study was to introduce a new method and validate the application in TKA both preoperatively and postoperatively.MethodsInstead of taking marginal landmarks as the tibial references, the tibial shaft axis was used to construct the new measurement method, which comprises the axis-patella (AP), joint axis-patella (jAP) indices and joint line height (JLH). Patellar heights were measured using the Insall-Salvati (IS), modified Insall-Salvati (mIS), Blackburne-Peel (BP), Caton-Deschamps (CD) indices, and the new method in 175 knees both preoperatively and postoperatively. Intraclass correlation coefficients and Pearson’s correlation analyses were respectively used to evaluate the reliabilities and correlations.ResultsThere were good correlations between the proposed method and the mIS, CD, and BP indices. High inter-observer reproducibility was found for AP (preoperative and postoperative 0.83), jAP (preoperative 0.82; postoperative 0.86) indices and JLH (preoperative 0.88; postoperative 0.95). High intra-observer repeatability was also found for AP (preoperative 0.85; postoperative 0.87), jAP (preoperative 0.83; postoperative 0.87) indices and JLH (preoperative 0.80; postoperative 0.92).ConclusionsThe new method is reliable for measuring patellar height before and after TKA, providing an alternative to distinguish between true and pseudo patella baja. Furthermore, JLH can be applied to assess and restore the joint line position in TKA.

Changes in patellar height and patellofemoral alignment following double level osteotomy performed for osteoarthritic knees with severe varus deformity

PurposeTo evaluate the effect of double level osteotomy (DLO), a combination of a lateral closed distal femoral osteotomy (LCWDFO) and medial opening wedge high tibial osteotomy (MOWHTO), on patellar height and patellofemoral alignment as compared to those of isolated MOWHTO. MethodsTwenty-six consecutive knees in 26 patients who underwent DLO (DLO group) constituted the study population. For comparative purpose, a control cohort (N: 26) matched for age, sex, and body mass index with the study group were selected from the patients who underwent isolated MOWHTO with an opening gap of more than 10 mm during the same period (MOWHTO group). Patellar height and patellofemoral alignment were assessed on radiographs preoperatively and at 2 years after surgery. For the patellar height, following parameters were measured on a lateral radiograph: Modified Insall-Salvati Index (mISI), modified Caton–Deschamps Index (mCDI), and modified Blackburne-Peel Index (mBPI). In the assessment of patellofemoral alignment, lateral patellar tilt (LPT) and lateral patellar shift (LPS) were measured on a skyline view. The measured values were statistically compared using the Student’s t-test. ResultsIn the DLO group, the patellar height measured by mCDI and mPBPI significantly decreased after surgery. As regards the patellofemoral alignment, LPT significantly decreased with no significant postoperative change detected for LPS. When the amounts of postoperative changes in radiological indices were compared between the DLO and isolated MOWHTO groups, no significant differences were detected for all parameters. ConclusionDLO induced reduction in patellar height and decreased lateral patellar tilt. Those changes in patellar position and orientation were similarly observed in isolated MOWHTO knees. Although DLO is specifically indicated for knees with severe varus deformity, the two surgical options for correction of varus knee deformity exerted similar influences on patellofemoral biomechanics.

Ultrasonographic evaluation of the patellar tendon length and elasticity after open-wedge high tibial osteotomy: A comparison with radiological and clinical parameters

BackgroundThe aim of this study was to evaluate the length and elasticity of the patellar tendon after open-wedge high tibial osteotomy (OWHTO). MethodsThis case-controlled, analytical study included patients who underwent unilateral OWHTO operation and a control group. The length, thickness, strain elastography, and strain ratio of the patellar tendon were measured. The outcome measures were the Insall–Salvati Index (ISI), Blackburne–Peel Index (BPI), Caton Index (CI), the International Knee Documentation Committee Score (IKDC), Oxford Knee Score (OKS) and Knee Injury and Osteoarthritis Outcome Score (KOOS), Ahlbäck classification, and mechanical axis. Elasticity of the patellar tendon obtained by strain elastography were graded as follows; hardest or hard tissue, intermediate tissue, and soft tissue. ResultsThe patellar tendon length was significantly shorter and patellar tendon thickness was significantly greater on the operated side compared with the values of the non-operated side and the control group (P<0.001 for all). Intermediate tissue was the most common elasticity grade (77%) for strain elastography on the operated side. Hardest tissue was the most common elasticity grade on the non-operated side of the patients (49.1%) and of the control group (70.0%). Patellar tendon length was correlated positively with IKDC, OKS, and KOOS values and patellar tendon thickness and strain ratio were correlated negatively with IKDC, OKS, and KOOS values. ConclusionThe patellar tendon seems to be shortened and thickened, with reduced stiffness after OWHTO. The ultrasound parameters are also associated with functional outcomes.

Genu Varum Correction: A Comparison of Conventional Open Wedge High Tibial Osteotomy versus Open Wedge Osteotomy with Sagittal Plane Cutting

Background: Open wedge high tibial osteotomy (OWHTO) is commonly utilized to correct genu varum. To decrease various complications of OWHTO, some modifications are needed. Methods: In a parallel randomized controlled clinical trial, 42 patients were divided into two groups: conventional OWHTO (control group) and OWHTO with the cut in the sagittal plane or distal tubercle osteotomy (OWHTO/DTO) (intervention group). Evaluation of the following items was conducted pre- and post-operatively: Knee Society Score (KSS) questionnaire, incidence of postoperative complications, patellar height by Blackburne-Peel (BP) ratio and Insall-Salvati Index (ISI), posterior tibial slope (PTS), tibiofemoral angle (TFA), Q-angle, medial proximal tibial angle (MPTA), three joint alignment radiography, and union radiological parameters. Results: The differences between preoperative and postoperative variables including the KSS, PTS, TFA, BP Index (BPI), ISI, MPTA, and Q-angle within the intervention and control groups were not statistically significant. In four cases (3 in the control group and 1 in the intervention group), the delayed union was observed but the complete union was achieved after a mean of 23 weeks. No nonunion was observed. Conclusion: Our results showed equal effectiveness for OWHTO/DTO compared with the conventional OWHTO.

Joint line elevation and tibial slope are associated with increased polyethylene wear in cruciate-retaining total knee replacement.

The purpose of this retrieval study was to determine the effect of implant positioning on wear, taking patient-related factors into account. Therefore, the volumetric material loss of 59 retrieved tibial liners was quantitatively determined using a coordinate measuring-machine. All retrievals were made of the same polyethylene and design by a single manufacturer. Using time in-situ and linear regression, a wear rate for each liner was determined and corrected for bedding-in. Backside damage was qualitatively scored. The following implant positioning parameters were obtained from radiographs: anatomical lateral-distal femoral angle, anatomical medial-proximal tibial angle, femoral tilt angle, and posterior tibial slope. The patella position was assessed by the Blackburne-Peel index and the Insall-Salvati ratio. Unlike the Insall-Salvati ratio, the Blackburne-Peel index is known to detect surgical joint line elevation. Using general linear modeling the most impactful factors on wear rate and backside damage was determined, thereby taking patient demographic factors into account. The mean volumetric wear rate was 11.6 mm3 /y. Wear decreased with older age (P = .021) and female sex (P = .001). The wear rate increased with joint line elevation as indicated from a decreased Blackburne-Peel index (P = .019), and increased with increased posterior tibial slope (P = .026). The backside damage score also increased with joint line elevation (P = .036). A Blackburne-Peel index decrease of 0.1, signifying joint line elevation, was found to increase the wear rate by 1.8 mm3 /y and increase back-sided wear. A high tibial slope (>7°) led to a 9.3 mm3 /y increase in wear rate compared with a low tibial slope (<3°). The results of this study demonstrate that tibial liner positioning has a significant impact on polyethylene wear with potential implications on osteolysis over time.

How Does Isolated Medial Patellofemoral Ligament Reconstruction Influence Patellar Height?

Background: Reconstruction of the medial patellofemoral ligament (MPFL) is the gold standard treatment for recurrent patellar dislocation. Patella alta has been reported in about half of patients with recurrent patellofemoral instability. Hypothesis: MPFL reconstruction (MPFLr) has a beneficial role in the correction of patellar height in patients with mild patella alta (Caton-Deschamps index [CDI] between 1.20 and 1.40). Study Design: Case series; Level of evidence, 4. Methods: Skeletally mature patients, with no history of previous or concomitant knee surgical procedures, who underwent isolated MPFLr using hamstring autograft for recurrent patellar instability between 2005 and 2018, were included in this study. The authors calculated CDI, modified Insall-Salvati index (MISI), and Blackburne-Peel index (BPI) ratios. Measurements done by 2 independent observers were calculated and used to compare pre- and postoperative patellar height (patella alta: CDI >1.20). Results: A total of 89 patients (95 knees) were included in the study, with a mean age of 25.0 years (range, 15.0-45.0 years). There were 70% women and 30% men. We found patella alta in 35.8% of cases preoperatively. Among them, 79.4% had reduced patellar height indices, within normal limits, postoperatively (mean follow-up, 18.4 ± 12.0 months). All the ratios showed a significant reduction in patellar height after surgery (CDI: 0.19 [range, –0.05, 0.60]; MISI: 0.22 [–0.14, 0.76]; BPI: 0.18 [–0.08, 0.59]; P < .00001). The CDI of 79.4% of the study knees was reduced to within normal limits postoperatively. The CDI was maintained within normal limits postoperatively in 93.4% of the knees with normal patellar height and reduced to normal in 50% of the knees with severe patella alta before surgery . No patient reported patella infera before surgery, whereas this condition was found in 8.2% of study patients postoperatively. A moderate correlation was reported between preoperative radiographic indices and their reduction after surgery (CDI: P < .001, ρ = 0.39; MISI: P < .001, ρ = 0.39; BPI: P < .001, ρ = 0.48). Conclusion: The higher the preoperative patellar height, the more important is the lowering effect of MPFLr using the hamstring for patellar instability. Bony procedures should not be indicated in patients with patellar instability and a CDI between 1.20 and 1.40.

Biplanar ascending opening-wedge high tibial osteotomy increases tibial tubercle–trochlear groove distance and decreases patellar height

ObjectivesTo assess the impact of a biplanar ascending opening-wedge high tibial osteotomy (OWHTO) on the alignment of the knee extensor mechanism and patellar height using preoperative and postoperative MRI.MethodsMedical records of all patients submitted to ascending biplanar OWHTO between July 2008 and March 2017 were retrospectively assessed. Five parameters of the patellofemoral joint—tibial tubercle–trochlear groove distance (TT-TG), patellofemoral (PF) axial engagement index, lateral patellar tilt, Blackburne-Peel index (BPI) and Caton-Deschamps index (CDI)—were measured by two blinded independent observers on both preoperative and postoperative MRIs. Interobserver reliability was assessed with the intraclass correlation coefficient (ICC). Paired t-test was performed to compare preoperative and postoperative measurements. The association of the amount of HTO opening and the assessed PF joint parameters was also investigated with Pearson correlation coefficient.Results26 patients who underwent ascending biplanar OWHTO were enrolled in this imaging analysis (63.4%) with a mean follow-up of 16.3 months (SD, 16.9). ICC for all measurements ranged between 73.3% and 89.3%. Postoperatively, TT-TG distance significantly increased by 2.0 mm±2.3 mm (p<0.001). Patellar height significantly decreased when evaluated by the BPI (p<0.001) and CDI (p=0.001). The amount of osteotomy opening significantly correlates with the postoperative BPI (p=0.023) and CDI (p=0.013).ConclusionThis study comprehensively reports significant increase on TT-TG distance after an ascending biplanar OWHTO using MRI. Small but significant decreases in patellar height were also observed and are correlated to the amount of axis correction.Level of evidenceLevel IV, retrospective case study.