Blackburne-Peel Ratios Research Articles

Isolated medial patellofemoral ligament reconstruction is valid to stabilize patellofemoral joint but uncertain to reduce patellar height in setting of lateral patellar dislocation and patella alta.

Medial patellofemoral ligament reconstruction (MPFLR) is the most commonly used surgical treatment for patients with lateral patellar dislocation (LPD). It is still poorly understood whether or not MPFLR has a contributory effect on decreasing patellar height. Forty-five patients who underwent isolated MPFLR for LPD and patella alta were evaluated with a mean follow-up period of 24months (22-25months). Knee joint functionswere evaluated by Banff patellofemoral instability instrument (BPII) 2.0 scores and Kujala scores. Patellofemoral engagement and stability were assessed by the patella tilt angle (PTA) and patellar congruence angle (PCA) measured by CT scans, and the patellar-glide test. Patellar height was calculated on lateral radiographs according to three methods: Caton-Deschamps ratios (CDR), Insall-Salvati ratios (ISR), and Blackburne-Peel ratios (BPR). A threshold value of p < 0.05 denoted a statistically significant difference. Significant improvements were found in both BPII 2.0 scores, which increased from 41.7 to 77.8 (p < 0.001) and Kujala scores, which increased from 49.2 to 85.5 (p < 0.001). Post-operative PTAs and PCA decreased from 19.6 ± 8.8 to -3.4 ± 6.2, and from 24.6 ± 7.3 to 13.1 ± 3.8 degrees respectively (p < 0.001). No patients showed lateral translation more than grade II in the patellar-glide test. Regarding patellar height, a tiny reduction (Δ = 0.02, Δ max = 0.09) was discovered in using CDR (p = 0.027), rather than ISR or BPR. All measurements of radiographic indices had an excellent intra- and inter-rater reliability (ICC > 0.75). Isolated anatomic MPFLR is sufficient to achieve good clinical outcomes, as well as patellofemoral stability and high rates of return-to-sport. However, it is unclear if the reconstructed MPFL has a contributory effect on reducing patellar height.

Patellar Tendon Imbrication Is a Safe and Efficacious Technique to Shorten the Patellar Tendon in Patients With Patella Alta.

Background:Patella alta has been noted to be a risk factor for recurrent patellar instability.Purpose:We conducted a radiographic study to determine whether a patellar tendon imbrication technique normalizes patellar height as well as whether the shortened length is maintained at a minimum 2-year follow-up.Study Design:Case series; Level of evidence, 4.Methods:A total of 54 consecutive patients were identified after a retrospective chart review was performed on patients who underwent patellar tendon imbrication between 2008 and 2013. Preoperative, 3 weeks postoperative, and minimum 2 years postoperative lateral radiographs were analyzed using Insall-Salvati (IS), Blackburne-Peel (BP), and Caton-Deschamps (CD) indices to determine the amount of shortening that was achieved after the procedure and to what degree that shortening was maintained at a minimum 2-year follow-up.Results:A total of 27 patients (32 knees) completed a minimum 2-year follow-up. The mean patellar tendon length preoperatively was 6.1 cm (range, 5-8 cm). At 3 weeks and 2 years, the mean tendon lengths were 5.1 and 5.2 cm, respectively. Thus, the mean ± SD change in patellar tendon length from preoperative to 3 weeks postoperative was 0.97 ± 0.67 cm. IS, BP, and CD ratios had minimal change (loss of correction) from 3-week to 2-year follow-up; the delta values were 0.04, –0.03, and 0.09, respectively. There were no complications directly related to the technique.Conclusion:Patellar tendon imbrication is a safe and effective procedure to correct patella alta in the setting of lateral patellar instability. On average, the technique allowed 1 cm of patellar tendon shortening and maintained the correction at a minimum 2-year follow-up. In the skeletally immature patient, this technique allows correction of patella alta by avoidance of a tibial tuberosity osteotomy.

Effect of Isolated Medial Patellofemoral Ligament Reconstruction in Patellofemoral Instability Regardless of Predisposing Factors.

The purpose of this study was to evaluate the outcomes of isolated medial patellofemoral ligament (MPFL) reconstruction, regardless of the presence of predisposing factors. A total of 21 knees that underwent isolated MPFL reconstruction from March 2014 to August 2017 were included in this retrospective series. Radiographs of the series of the knee at flexion angles of 20, 40, and 60 degrees were acquired. The patellar position was evaluated using the patellar tilt angle, sulcus angle, congruence angle (CA), and Caton-Deschamps and Blackburne-Peel ratios. To evaluate the clinical outcome, the preoperative and postoperative International Knee Documentation Committee (IKDC) and Lysholm knee scoring scales were analyzed. To evaluate the postoperative outcomes based on the predisposing factors, the results were separately analyzed for each group. Regarding radiologic outcomes, 20-degree CA was significantly reduced from 10.37 ± 5.96° preoperatively to -0.94 ± 4.11° postoperatively (p = 0.001). In addition, regardless of the predisposing factors, delta values of pre- and postoperation of 20-degree CA were not significantly different in both groups. The IKDC score improved from 53.71 (range: 18-74) preoperatively to 94.71 (range: 86-100) at the last follow-up (p = 0.004), and the Lysholm score improved from 54.28 (range: 10-81) preoperatively to 94.14 (range: 86-100) at the last follow-up (p = 0.010). Isolated MPFL reconstruction provides a safe and effective treatment for patellofemoral instability, even in the presence of mild predisposing factors, such as trochlear dysplasia, increased patella height, increased TT-TG distance, or valgus alignment. This is a Level 4, case series study.

Patella Baja in Total Knee Arthroplasty.

Patella baja in total knee arthroplasty can result in impingement, pain, and decreased range of motion. Etiology can range from previous knee surgeries such as anterior cruciate ligament reconstruction, retrograde femoral nail, infrapatellar fat pad resection, and previous total knee arthroplasty. Diagnosis can be confirmed by one of a number of measurements of patellar height including Insall-Salvati and Blackburne-Peel ratios. It is important to differentiate between true patella baja and pseudopatella baja by patellar height ratio. Treatment includes correct identification of the underlying etiology and appropriate management. Surgical management strategies include tibial tubercle osteotomy, distal femoral augment and revision, proximalization of the patellar component, modification of the anterior tibial component, and/or Z-plasty of the patellar tendon. We review the outcomes for each of these procedures.

Is Pseudo-Patella Baja Really a Serious Complication of Total Knee Arthroplasty?

BackgroundThe available evidence on pseudo-patella baja (PPB) is limited. The purpose of this study is to investigate prospectively the occurrence of PPB after primary total knee arthroplasty and its clinical consequences in a large series of patients with a minimum follow-up of 2 years. PPB was defined as a patella distally displaced in relationship to the femoral trochlea with absence of patellar tendon shortening (Grelsamer RP. J Arthroplasty 2002;17:66-69) due to elevation of the joint line. MethodsThis study is a prospective case series of 354 patients with a mean age of 71.7 (range 52-87) years. Clinical evaluation was performed by the Knee Society Scores (KSS), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Short-Form 12-item (SF12), and range of motion. Patellar height was assessed by the Insall-Salvati and Blackburne-Peel ratios. ResultsThe mean follow-up was 3.6 (range 2.0-6.6) years. Postoperatively, 286 (80.7%) patients had a normal patellar height, 17 (4.8%) had true patella baja (TPB), and 51 (14.4%) had PPB. There were no significant differences between the 3 groups in mean KSS-function (P = .107), range of motion (P = .408), WOMAC-pain (P = .095), WOMAC-stiffness (P = .279), or SF12-mental (P = .363). Between normal and PPB groups, there were no significant differences in mean KSS-knee (P = .903), WOMAC-function (P = .294), or SF12-physical (P = .940). However, the TPB group had significantly lower mean KSS-knee (P = .031), WOMAC-function (P = .018), and SF12-physical (P = .005) as compared with either 2 other groups. ConclusionPPB was a relatively common finding, but no significant differences in terms of clinical outcomes were found as compared to patients with postoperative normal patellar height. TPB was infrequent, but these patients had significantly worse clinical outcomes than those with PPB or normal patellar height.

Patella Height in Different Ethnic Populations: An Observational Multicenter Study.

Patella height appears to have a crucial role in knee biomechanics. Patellar malalignment and maltracking are therefore believed to be associated with development and progression of patellofemoral pain and disease. Published data are scant regarding the effect of everyday tasks on patella height and patellofemoral disease. We included 150 subjects in a retrospective observational study. Group A had 75 subjects (24 male and 51 female, with a mean age of 58.5 yr), whose daily activities included squatting (the traditional Muslim praying position called Sujud). Group B had 75 subjects (42 male and 33 female, with a mean age of 47.6 yr), who were non-Muslim. Patella height was measured using Insall-Salvati (IS) and Blackburne-Peel (BP) ratios. The mean IS ratio was 0.86 (confidence interval [CI]: 0.7-1.02) for group A and 1.1 (CI: 0.96-1.23) for group B. The mean BP ratio was 0.66 (CI: 0.49-0.83) for group A and 0.89 (CI: 0.73-1.04) for group B. We found 26 subjects (34.7%) in group B to have patella alta, when measured by either ratio, compared to one subject (1.3%) in group A (p < 0.01) with patella alta. We found 61 subjects (81.3%) in group A to have patella baja, when measured by either ratio, compared to 21 subjects (28%) in group A (p < 0.01) with patella baja. In group A, the IS ratio was reduced in 29 subjects (38.7%), the BP ratio was reduced in 59 subjects (78.7%), and both were reduced in 27 subjects (36%). A similar pattern was noted for group B. Our results show that a significant increase in patella baja was associated with repeated squatting/kneeling, compared to the predominance of patella alta in the control group. On the basis of these findings, we hypothesize that biomechanical stresses associated with repeated hyperflexion of the knee asymmetrically affect the more flexible quadriceps muscle fibers greater than patella tendon fibers. Thus, repeated hyperflexion in everyday tasks leads to elongation of quadriceps fibers and patella baja.

Knee Deformities in Children With Down Syndrome: A Focus on Knee Malalignment.

Patellofemoral instability (PFI) has been the most reported knee abnormality in people with Down syndrome. Other reported knee abnormalities have been associated with PFI and different management approaches have been described with variable outcomes. The aim of this study was to describe the anatomic variations of the knee in children with Down syndrome. A comparison between knees with and without PFI was performed and our experience in treating knee abnormalities in Down syndrome was also reported. Records of all children with Down syndrome were reviewed. Two groups were identified (knees with and without PFI). Radiographic measurements included the mechanical and anatomic lateral distal femoral angles, medial proximal tibial angle, angle of depression of medial tibial plateau, lateral tibial translation, and distal femoral physis-joint angle. On the lateral view, Insall-Salvati and Blackburne-Peel ratios were measured. The sulcus angle was measured on the tangential view. Measurements were compared between the 2 groups (with and without PFI).Knees with PFI were divided into 3 subgroups based on their treatment (group A: surgical valgus correction, group B: surgical soft tissue procedures for PFI, and group C: conservative treatment). Preoperative radiographs were used for the surgical group and last available radiographs were used for the conservative group. Clinical and radiographic data were compared between the groups. For groups A and B, clinical and radiographic data were also compared between preoperative and last visits. Of the 581 children with Down syndrome, 5% (31 children: 22 females, 9 males) had PFI in 56 knees. Mean age at diagnosis was 11.5±3.5 years. Of the remaining 550 children, 75 children had radiographs for 130 knees. Knees with PFI had significantly more valgus and a larger distal femoral physis-joint angle. Depression of the medial tibial plateau and lateral tibial translation were noted in knees with PFI. Insall-Salvati ratio was higher and the sulcus angle was larger in the PFI group.Of the 56 knees with PFI; 10 knees were in group A, 11 knees in group B, 33 knees in group C, and the remaining 2 knees had combined procedures. Preoperative mechanical and anatomic lateral distal femoral angles were smaller in group A than in group B or C. Grades of PFI improved in group B after surgery. This improvement was not noted in group A. In children with Down syndrome, different variations of the knee anatomy can be found. Although PFI might be the most evident knee abnormality, other underlying deformities are common. Treatment of the PFI should be planned through a comprehensive anatomic approach that addresses all aspects of knee deformity. Level IV-prognostic and therapeutic study.

Proximalisation of the tibial tubercle gives a good outcome in patients undergoing revision total knee arthroplasty who have pseudo patella baja

The aim of this study was to compare the outcome of revision total knee arthroplasty (TKA) with and without proximalisation of the tibial tubercle in patients with a failed primary TKA who have pseudo patella baja. All revision TKAs, performed between January 2008 and November 2013 at a tertiary referral University Orthopaedic Department were retrospectively reviewed. Pseudo patella baja was defined using the modified Insall-Salvati and the Blackburne-Peel ratios. A proximalisation of the tibial tubercle was performed in 13 patients with pseudo patella baja who were matched with a control group of 13 patients for gender, age, height, weight, body mass index, length of surgery and Blackburne-Peel ratio. Outcome was assessed two years post-operatively using the Knee Society Score (KSS). The increase in KSS was significantly higher in the osteotomy group compared with the control group. The outcome was statistically better in patients in whom proximalisation of > 1 cm had been achieved compared with those in whom the proximalisation was < 1 cm. In this retrospective case-control study, a proximal transfer of the tibial tubercle at revision TKA in patients with pseudo patella baja gives good outcomes without major complications. Cite this article: Bone Joint J 2017;99-B:912-16.

Patellar Height After Total Knee Arthroplasty: Comparison of 3 Methods

BackgroundTotal knee arthroplasty (TKA) is the gold standard procedure for knee osteoarthritis. However, there have been conflicting reports concerning whether TKA is associated with modifications in patellar height. This controversy might be partially explained by the diversity of methods used to measure patellar height. Therefore, we aimed at assessing the reproducibility of 3 radiological indices commonly used to evaluate patellar height—Insall-Salvati (IS), Blackburne-Peel (BP), and Caton-Deschamps (CD) ratios. Additionally, we aimed at evaluating the short-term differences between preoperative and postoperative patellar heights as measured by those 3 methods. MethodsPatellar heights were blindly measured by 2 researchers using IS, BP, and CD ratios in 203 knees. Interobserver agreement was evaluated by determination of intraclass correlation coefficients (ICC) and Bland-Altman plots. Preoperative and postoperative patellar heights were compared with Wilcoxon test. The association between postoperative pain and modifications in patellar height was assessed using Mann-Whitney U test. ResultsHigh interobserver agreement was found for IS (preoperative and postoperative ICC = 0.93), BP (preoperative ICC = 0.89; postoperative ICC = 0.91), and CD (preoperative ICC = 0.89; postoperative ICC = 0.90) ratios. Preoperative and postoperative patellar heights were not significantly different whatever the method used. Postoperative pain was reported after 23% procedures and was significantly associated with wider patellar height variations as measured by the BP ratio (P = .018). ConclusionThe methods evaluated appear to be reproducible. Although patellar height tended to be lower when measured postoperatively, this difference was not significant for any of the methods studied.

Assessing the validity of the modified Blumensaat method for radiographic evaluation of patellar height.

Although several indexes have been used for patellar height evaluation, the literature on patellar height evaluation using a femoral reference point is scant. We have previously reported on a new index, the modified Blumensaat (MB) method, which evaluates the patellar height using a femoral reference point. The purpose of this study was to evaluate the validity of the MB method. In addition to 10 volunteers (group C), 10 men (group M) and 10 women (group F) who underwent knee surgery were selected for the study. The Insall-Salvati (IS), modified IS (MIS), Blackburne-Peel (BP), MB, and modified intercondylar-shelf-angle-corrected Blumensaat (MIB) ratios were measured on lateral knee radiographs with the knee in 30°, 40°, and 50° flexion. In group C, the MB and MIB ratios were similar; the IS ratio was not dependent on the knee flexion angle, and there was no significant difference in the MIS and BP ratios between 40° and 50° of knee flexion and in the MB and the MIB ratios between 30° and 40° of knee flexion. There were no differences between group M and group F with respect to any of the indexes. Furthermore, the differences in all indexes among the different knee flexion angles, in groups M and F, were similar to those in group C. The MB method is applicable for patellar height evaluation and is recommended with a knee flexion angle of 30°-40°.

High tibial open wedge osteotomy below the tibial tubercle: clinical and radiographic results

The purpose of this study was to evaluate the clinical and radiographic results of open wedge HTO below the tubercle for genu varum in relatively young patients. Thirty-seven knees in 19 patients with genu varum treated by open wedge HTO below the tubercle between 2001 and 2008 were retrospectively studied. Median follow-up was 36months (12-108), and median patient age at the time of surgery was 26years (16-45). Clinical results were evaluated using Lysholm knee scores and Hospital for Special Surgery knee scores. Satisfaction with the results of surgery (0-10 points) was subjectively evaluated using operative scar (1-5 points) and leg shape (1-5 points) results at follow-up. Radiographic evaluations were made using: (1) tibiofemoral angles, (2) mechanical axis deviations, (3) varus-valgus inclinations of the tibial plateau, (4) tibial slopes, and (5) Insall-Savati and (6) Blackburne-Peel ratios. All but one patient achieved radiographic healing and union at the osteotomy site at an average of 3months postoperatively. Average Lysholm knee score improved from 89.4±8.7 preoperatively to 98.6±2.5 at final follow-up (P=0.0001), and mean HSS score improved from 91.1±5.6 preoperatively to 98.5±2.0 at final follow-up (P=0.0001). Mean patient satisfaction score at final follow-up was 8.6±1.0, and mean tibiofemoral angle increased from -1.6° preoperatively to 7.7° at final follow-up (P<0.0001). The point where the mechanical axis crosses the tibial plateau also shifted significantly from 15.0% preoperatively to 50.6% at final follow-up (P=0.0002). However, mean posterior tibial slope did not change significantly (9.7° preoperatively and 8.7° at final follow-up; P=NS), and neither did patella heights as measured by Insall-Savati and Blackburne-Peel ratios. Both functional assessment and radiographic measures indicated that HTO below the tibial tubercle leads to significant improvements in radiographic parameters and knee function without changes in patellar height or posterior tibial slope. The results obtained support the hypotheses that opening wedge HTO below the tibial tubercle should be recommended in relatively young patients with genu varum. Therapeutic study, Level IV.

Patellar height measurement in trochlear dysplasia

A number of measurements of patellar height are in clinical use all of which reference from the tibia. The patellotrochlear index (PTI) has been proposed recently as a more accurate reflection of the functional height of the patella and described in normal knees. We compared patellar height measurements in patients with patellofemoral dysplasia. In a retrospective analysis of the MRI scans of 33 knees in 29 patients with patellofemoral dysplasia we assessed the inter- and intraobserver reliability of four patellar height measurements: the recently described PTI, Insall-Salvati (IS), Blackburne-Peel (BP) and Caton-Deschamps (CD) ratios. We also assessed the correlation between the different measurements in predicting patella alta. Three blinded observers on two separate occasions performed the measurements. There were 21 females and 8 males with a median age of 21 years (range 13-33). Statistical analysis revealed good inter-observer reliability for all measurements (0.78 for PTI, 0.78 for IS, 0.73 for BP and 0.77 for CD). Intra-observer reliability was also good (0.80, 0.83, 0.75 and 0.78, respectively). There was weak correlation between the PTI and the other ratios for patella alta. There was a strong correlation between the CD and BP ratios (0.96) and a moderate correlation between IS and CD and IS and BP ratios (0.594 and 0.539, respectively). We propose the PTI as a more clinically relevant measure than the IS, CD and BP ratios.

Tibial slope and patellar height after opening wedge high tibia osteotomy using autologous tricortical iliac bone graft

Our aim was to evaluate the alteration in angle of posterior slope of the tibia and the degree of patellar height following medial opening wedge high tibia osteotomy(HTO) using autologous tricortical iliac bone graft in 32 consecutive patients.Twenty three females and nine males underwent medial opening wedge high tibia osteotomy (HTO) using autologous tricortical iliac bone graft in 34 knees (33 primary medial compartment osteoarthritis and 1 idiopathic osteonecrosis of medial tibial condyle). The posterior slope of tibia was determined by the proximal tibial anatomical axis. Patellar height was measured by the Insall-Salvati and the Blackburne-Peel ratios. Preoperative and postoperative (last follow up) values of these three parameters were compared. The intra- and interobserver variability of these methods was determined before and after operation.At the end of mean follow up of 3 years this procedure produced no significant change in posterior slope. Pre and postoperative posterior slope were 8.7°±3.6° and 8.2°±2.8° respectively (P=0.412).Pre and postoperative Insall-Salvati ratios were 0.93±0.10 and 1.05±0.11 respectively (P<0.001). The Insall-Salvati ratio increased in 94% of patients and patellar ligament length was significantly increased.The distance between the patellar and tibiofemoral joint line decreased in 82% of patients. The mean Blackburne-Peel ratio declined from 0.71±0.12 to 0.61±0.13 (P<0.001). Twenty six percent of postoperative Blackburne-Peel values satisfied the radiographic criterion for patellar infera (Blackburne-Peel ratio<0.54).There was no difference in the intra-and interobserver variability of measurements either before or after HTO.Opening wedge HTO using autologous tricortical iliac bone graft with internal fixation and early mobilisation prevented change in posterior slope of tibia, lengthened the patellar ligament and elevated the tibiofemoral joint line when the mean ratio of anterior and posterior gap at the osteotomy site was around two-thirds.

Patellar height and the inclination of the tibial plateau after high tibial osteotomy

Our aim was to compare the degree of patellar descent and alteration in angle of the inclination of the tibial plateau in lateral closing-wedge and medial opening-wedge high tibial osteotomy (HTO) in 51 consecutive patients with osteoarthritis of the medial compartment and varus malalignment. Patellar height was measured by the Insall-Salvati (IS) and the Blackburne-Peel (BP) ratios. The tibial inclination was determined by the Moore-Harvey (MH) method. Multivariate linear regression analysis was used to determine the influence of the type of HTO (closing vs opening wedge) on the post-operative patellar height or tibial inclination. The intra- and interobserver variability of these methods was determined before operation and at follow-up at one year. After an opening-wedge HTO the patellar height was significantly more decreased (mean post-operative difference: IS = 0.15; 95% confidence interval (CI) 0.06 to 0.23; BP = 0.11; 95% CI 0.05 to 0.18) compared with a closing-wedge HTO. The angle of tibial inclination differed significantly (mean post-operative difference MH = -6.40 degrees; 95% CI -8.74 to -4.02) between the two HTO techniques, increasing after opening-wedge HTO and decreasing after closing-wedge HTO. There was no clinically-relevant difference in the intra- and interobserver variability of measurements of patellar height either before or after HTO.

Patellar tendon length change after anterior cruciate ligament reconstruction using the midthird patellar tendon.

The purpose of this study was to determine if use of the midthird patellar tendon autograft contributes to or causes patellar tendon shortening or patella baja in anterior cruciate ligament reconstruction. Thirty-six patients undergoing arthroscopically assisted midthird patellar tendon autograft anterior cruciate ligament reconstruction were studied prospectively. Intraoperative patellar tendon length changes were measured. Half of the patients had the tendon defect closed and half had it left open (closing peritenon only). Radiographic tendon length changes and patella baja were assessed using Insall-Salvati and Blackburne-Peel ratios measured on 45 degrees lateral knee radiographs using an adjustable polypropylene jig. Bilateral films were obtained preoperatively and at 2 weeks, 3 months, and 6 months postoperatively. No patients demonstrated evidence of patellar tendon shortening greater than the 5.5% measurement error. Tendon defect closure resulted in negligible tendon shortening intraoperatively, averaging 2.28% (1.11 mm). Of the 18 patients whose defects were closed, 5 showed no shortening. The remaining 13 patients had measurable tendon shortening less than 4% (2 mm). No patients developed patella baja.