Observations on patellar height after proximal tibial osteotomy

Sixty-six knees (sixty patients) that had had a proximal tibial osteotomy were evaluated to determine if any alteration of the patellar height had occurred as a result of the operation. Eighty-nine per cent of the patellae, as measured by the Insall-Salvati index, and 76.3 per cent, as measured by the Blackburne-Peel index, were observed to be lowered as they appeared on the postoperative lateral radiograph. This was probably due to shortening of the patellar ligament after prolonged immobilization in a cast, interstitial scarring of the patellar ligament, and new-bone formation in the area of insertion of the patellar ligament. There was no correlation between the postoperative height of the patella and the need for subsequent revision to a total knee replacement.     

Patellar height after barrel-vault high tibial osteotomy.

The purpose of the study was to assess the influence of barrel-vault high tibial osteotomy on patellar position and to evaluate the reliability and interobserver variability of three patellar height ratios. The radiographs of 24 knees that had undergone barrel-vault height tibial osteotomy with available preoperative as well as postoperative radiographs of the last follow-up were enrolled in the study. The patellar position was evaluated with the use of the Insall-Salvati, Blackbourne-Peel and Caton-Linclau methods. The indices were calculated with the tibial slope angle measured by the Moore-Harvey method. The average patellar index in the Blackburne-Peel and Caton-Linclau measurements had a statistically significant tendency to increase after barrel-vault tibial osteotomy. The results of the Insall-Salvati assessment method showed no statistically significant differences. Intrasession ICCs (intraclass correlation coefficient) varied between 0.8 and 0.99. The kappa value for the inter-observer agreement of all three ratios determined varied between 0.48 for the Blackburne-Peel index and 0.5 for the Insall-Salvati and Caton-Linclau indices. The average tibial slope before the surgery was 11.8 degrees (+/- 3.6) and decreased to 6.6 degrees (+/- 4.3). No significant associations between the index change and tibial slope change were detected. The data suggest that since some of patellar height indices measure different anatomical relationships, comparable types of indices should be used in order to estimate the patellar height or patellar relation to the joint line.     

Patellar height and the inclination of the tibial plateau after high tibial osteotomy. The open versus the closed-wedge technique

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.     

Anterior opening wedge osteotomy of the proximal tibia for anterior knee pain in idiopathic hyperextension knees

We analysed 20 patients with 24 knees affected by idiopathic genu recurvatum who were treated with an anterior opening wedge osteotomy of the proximal tibia because of anterior knee pain. We managed to attain full satisfaction in 83% of the patients with a mean follow-up of 7.4 years. The mean Hospital for Special Surgery score was 90.3 (range 70.5-99.5), and the mean Knee Society score score was 94.6 (70-100) for function and 87.7 (47-100) for pain. The mean Western Ontario and McMaster University Osteoarthritis Index score for knee function was 87.5 (42-100), for stiffness 82.8 (25-100) and for pain 87.3 (55-100). Radiographs showed a significant increase in posterior tibial slope of 9.4 deg and a significant decrease of patellar height according to the Blackburne-Peel method of 0.16 postoperatively. No cases of non-union, deep infection or compartment syndrome were seen. No osteoarthritic changes in the lateral or medial knee compartment were found with more than 5 years' follow-up in 16 patients with 19 affected knees. Three out of the four dissatisfied patients had a patella infera which led to patellofemoral complaints. One patient in the study underwent a secondary superior displacement of the patella with excellent results. We conclude that in a selected group of patients with idiopathic genu recurvatum and anterior knee pain an opening wedge osteotomy of the proximal tibia can be beneficial.     

胫骨高位截骨术后髌骨低位

目的探讨胫骨高位截骨术治疗膝关节内侧间室骨性关节炎后髌骨低位与胫骨近端关节面后倾角度改变之间的关系,并提出预防和控制髌骨低位的措施。方法41例(48膝)膝关节内侧间隙骨性关节炎患者,男30例(33膝),女11例(15膝);年龄45～56岁,平均52岁。所有病例均行胫骨外侧高位楔形截骨术。根据术前测量的截骨角度(内翻角+正常外翻角+过度矫形3°～5°),在槽刀和导向器等辅助下切除楔形骨块,用改良Giebel槽式钢板拉力螺钉内固定,术后不需外固定。测量48膝行胫骨高位截骨术患者术前及术后X线片的Insall-Salvati比值、胫骨近端关节面后倾角度、胫骨结节高度、患肢解剖轴线角度,并用χ2检验和直线回归分析进行统计学处理。检验时假定术后胫骨近端关节面后倾角度减小≥5°以及髌骨高度下降≥10%具有临床意义。结果术后胫骨近端关节面后倾角度比术前平均减小6.14°,Insall-Salvati比值术前、术后相对变化率为10.6%,胫骨结节高度比术前平均下降3.13mm。64.6%的病例胫骨近端关节面后倾角度减小≥5°。按Insall-Salvati比值结果,56.2%的病例髌骨高度相对下降率≥10%。胫骨近端关节面后倾角度的减小与髌骨高度的相对下降具有显著的统计学相关性。结论胫骨近端关节面后倾角度的减小与髌骨低位具有相关性,提示在施行胫骨高     

Modifizierung des Blackburne-Peel-Index zur besseren Anwendung in der Knieendoprothetik

Background

The methods currently used to measure patella height in relation to the tibiofemoral joint line after total knee arthroplasty are not easily reproducible. For this reason we modified the Blackburne-Peel ratio.

Materials and Methods

Instead of taking the tibial joint line as the reference line, we constructed a tangent on the femoral condyle. In addition, we took the greatest diameter of the patella from the tip of the patella as a measuring line.

Results

Compared with the classic Blackburne-Peel and Caton-Deschamps ratios, it was much easier to determine the patella height in osteoarthritic knees and after total knee replacement using this modified Blackburne-Peel ratio. Factors such as the height of the polyethylene inlay, the slope of the tibial component, and superimposition of the patellar joint line can be disregarded. Preoperative and postoperative reference lines can be compared readily. Furthermore, the classic Blackburne-Peel ratio shows a greater tendency to interpret the measurements after total knee arthroplasty as pseudo-patella baja. The interobserver variability was good for all ratios.

Conclusion

We can therefore recommend the modified BlackburnePeel ratio for measuring patella height in relation to the tibiofemoral joint line after total knee arthroplasty.     

Influence of prosthetic joint line position on knee kinematics and patellar position

Prosthetic joint line position after total knee arthroplasty (TKA) was investigated using sagittal roentgenograms obtained from six fresh frozen cadaver knees. A specially designed knee testing device was developed that allowed for a controlled flexion angle while maintaining a constant quadriceps force. Pre- and postoperative roentgenograms were obtained from 30 degrees to 120 degrees in 15 degrees intervals. Steinman pins inserted into the medial femoral condyle and patella were used as reference points in the roentgenograms. A displacement vector between the medial femoral condyle and tibial plateau was used to analyze the tibiofemoral joint relationship. The functional patellar length (Insall-Salvati ratio), was used to determine correct patellar height. Another displacement vector was used to measure the patellofemoral joint relationship, and the angle between the patellar cut surface and femoral long axis was also calculated. Bone resection thickness from the femoral, tibial, and patellar surfaces was equal to the prosthetic thickness. This reconstructive scheme produced correct ligament balance and flexibility of the knee without the aid of tensioning devices or special measurements. Patellar tracking appeared to be identical before and after surgery. This accurate but simple surgical technique also reproduced normal knee extensor mechanisms that may influence longevity and long-term results of TKA.     

Comparison of the change in patellar height between opening and closed wedge high tibial osteotomy: measurement with a new method

Purpose

The purposes of this study were to examine patellar height at preoperation and postoperation, and compare the change of patellar height between opening wedge high tibial osteotomy (HTO) and closed wedge HTO by using Insall-Salvati (IS) ratio and our original method.

Methods

Twenty patients (26 knees) were included. There were 6 males (6 knees) and 14 females (20 knees). Sixteen knees underwent closed method and 10 knees underwent opening method. Patellar height was measured at preoperation, immediately after the operation (postoperation) and 1 year after the operation according to IS ratio and modified Blumensaat (MB) ratio. We defined MB ratio as the ratio of distance from Blumensaat line to the midpoint of patellofemoral joint of patella against the length of Blumensaat line.

Results

In opening wedge HTO, though IS ratio significantly increased postoperatively compared with preoperative IS ratio, IS ratio at 1 year after operation was not significantly different from preoperative values. MB ratio at postoperation and that at 1 year after the operation significantly decreased compared with preoperative MB ratio. In closed wedge HTO, there was no difference between preoperative and postoperative values of both IS ratio and MB ratio.

Conclusions

In the postoperative period after opening wedge HTO, IS ratio was significantly increased, whereas MB ratio was decreased. We recommend that patients with low preoperative MB ratio must be treated with closed wedge HTO.     

Patella infera following arthroscopic anterior cruciate ligament reconstruction

Fifty patients who had an arthroscopic anterior cruciate ligament reconstruction for chronic insufficiency were reviewed at an average of 13.6 months following surgery. Among these patients, 32% complained of anterior knee pain that interfered with daily activities. Radiographic patella infera was present in 12% of patients using the Insall-Salvati ratio and in 16% using the Blackburne-Peel ratio. Radiographic patella infera did not correlate with the clinical problem of postoperative anterior knee pain. However, loss of knee extension of greater than 5 degrees correlated highly with pain (p=0.002).     

Patellar infera after high tibial osteotomy

Forty-six knees in 41 patients that had undergone high tibial osteotomy (HTO) were evaluated to assess the potential correlation between alteration in the inclination of the proximal tibial articular surface and subsequent patellar height. Of the knees examined, 61% lost > or =5 degrees of posterior tibial inclination after HTO, whereas 54% of knees showed a relative lowering of patellar height of >10%, as measured by the Insall-Salvati ratio. The loss of the normal posterior tibial inclination was found to have a statistically significant association with the subsequent loss of the patellar height. Clinically, these results suggest that careful preservation of the posterior tibial inclination at the time of HTO could minimize the risk of subsequent patellar infera and alteration in patellofemoral mechanics.     

Editorial Commentary: Avoid Creating an Oblique Joint Line After an Opening Medial Wedge High Tibial Osteotomy

A medial opening wedge high tibial osteotomy is a cost-effective procedure for younger patients with symptomatic medial compartment knee arthritis. A high rate of success can be expected, but excessive postoperative joint line obliquity is associated with inferior clinical outcomes. If preoperative planning predicts that the postoperative medial proximal tibial angle, the medial angle between the tibial anatomical axis and the joint line of the proximal tibia, will exceed 95°, a surgeon should consider performing a double-level osteotomy (combined proximal tibial and distal femoral osteotomies).     

内侧撑开和外侧闭合胫骨高位截骨术治疗膝内翻骨关节炎

目的 比较两种胫骨高位截骨术的手术方法和临床结果.方法 膝内翻骨关节炎患者68例,其中37例采用外侧闭合胫骨高位截骨术(closed wedge high tibial osteotomy,CWO),31例采用内侧撑开胫骨高位截骨术(open wedge high tibial osteotomy,OWO).术后摄X线片测量胫骨平台后倾角、髌骨高度、胫骨股骨角、内侧胫股关节间隙宽度,并行HSS和Lysholm功能评分.结果 患者均随访24个月以上.术前、术后两组HSS和Lysholm评分差异均无统计学意义.(1)CWO组术前胫骨平台后倾角8.57°±1.63°、术后5.03°±1.24°,OWO组术前8.71°±1.66°、术后10.10°±1.30°,差异均有统计学意义.(2)CWO组术前Insall-Salvati指数0.880±0.053、术后0.820±0.049,差异有统计学意义;OWO组术前0.892±0.043、术后0.897±0.042,差异无统计学意义.CWO组术前Blackburne-Peel指数0.804±0.040、术后0.801±0.339,差异无统计学意义;OWO组术前0.815±0.039、术后0.766±0.037,差异有统计学意义.(3)术后CWO组外翻8.06°±2.75°,OWO组外翻8.65°±1.46°.结论 膝内翻骨关节炎的内侧撑开和外侧闭合胫骨高位截骨术有相似的手术效果,内侧撑开截骨术截骨角度更加准确.外侧闭合胫骨高位截骨术后可出现胫骨后倾减小和髌韧带短缩,内侧撑开截骨术后易出现胫骨后倾增加和髌骨至关节线距离减小.     

Tibial tubercle osteotomy in patello-femoral instability and in patellar height abnormality

The aim of this study was to present the different surgical procedures of tibial tubercle osteotomies for patellar instability or patellar mispositioning such as patella alta or patella infera. This study analysed the Caton–Deschamps index used for assessment of vertical patella height in order to make a precise plan for tibial tuberosity osteotomies. This study included 61 knees (50 patients) treated for patellar instability with patella alta and 24 patients treated for patella infera of mechanical origin. The results of medial transfer of the tibial tuberosity, with or without distal transfer in cases of patellar instability with patella alta, gives excellent results for stability in 76.8% of the cases. The results of the proximal transfer of the tibial tuberosity in cases of patella infera were excellent or good in 80% of the cases in our series of 24 patients. A precise preoperative plan is needed with determination of the vertical patellar height using the Caton–Deschamps index and the situation of the tibial tuberosity and the Tibial Tubercle to Trochlear Groove distance (TT-TG) of the knee on CT scan in order to obtain satisfactory results.     

Patella baja after the modified Coventry-Maquet high tibial osteotomy

This study assessed the Modified Coventry-Maquet technique for high tibial osteotomy with respect to the incidence of patella baja using the Insall-Salvati index. Twenty-seven high tibial osteotomies performed or supervised by a single surgeon (A.E.G.) between 1996 and 2000 were analyzed. Eight knees were excluded; the remaining 19 were evaluated. Mean patient age at surgery was 49 years, and the mean postoperative Insall-Salvati index was 0.83. This represented an average decrease in patellar height of 15% (P<.000001). The incidence of new-onset postoperative patella baja was 26% (5/19). Tibial posterior slope increased by an average of 4.3 degrees (P<.0001). Mean tibial tuberosity height decreased by an average of 8.9 mm (P<.0001). The mechanical axis was corrected by an average of 11.9 degrees and loss of range of motion postoperatively was negligible. The correlation between tibial slope, tuberosity height, and patellar height was not significant. The modified Coventry-Maquet procedure achieved excellent valgus knee realignment while losing minimal range of motion and avoiding intra-articular fracture and nonunion. This incidence of patella baja was comparable to most, and better than some, published series.     

The management of patella infera in current practice

Patella infera described by Caton et al.The measurement is made in 1982 is an accompanying symptom in certain knee affections secondary to the abnormal situation of the patella. The measurement is made on the X-ray with sagittal view after measuring the patellar height, using the original technique described by the author, when the ratio between the articular surface of the patella and the distance form the patellar tip to the tibial tubercle. Indications of surgery may be when this ration is inferior or equals 0.6. The origin of the patella infera can be mechanical or inflammatory. The operative technique addresses the etiology. In current practice, the patellar height and the patellar tendon length may be evaluated using a sagittal section MRI. In the authors’ experience, when the Caton ratio is lower or equals 0.6 and when the length of the patellar tendon is over 25 mm, the indication of surgery includes proximal transfer of the tibial tubercle. If the length of the patellar tendon is less than 25 mm, it is often necessary to perform a patellar tendon lengthening (PTL). This type of surgery is contraindicated in the authors’ experience in depressive or pusillanimous subjects. The two surgical techniques are described. Both techniques use an anterior and medial approach. The proximal transfer of the tibial tubercle (PTT) includes medial and lateral retinaculum release. The tibial tubercle is detached and transferred upwards according to the pre-operative planning generally 1 or 2 cm and is fixed with 2 screws. PTL includes a medial and lateral retinaculum release often with the fat pad. The patellar tendon is dissociated in the middle over its whole length, and the medial pad is detached of the tibial tubercle and the lateral of the patella. After lengthening, the edges of the tendon are sutured, and this suturing reinforced. Alternative procedures may be used when PTT or PTL are not possible, using transplantation with an allograft of the extensor system or a plasty with hamstring muscles.     

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

BACKGROUND High 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.AIM To compare of the radiological results of two different techniques: acute opening wedge correction(a plate and screw) and gradual correction(external fixator).METHODS A 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.RESULTS Demographics 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).CONCLUSION Reliable 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.     

Patellar clunk syndrome after posterior stabilized total knee arthroplasty

Two hundred thirty-six posterior stabilized total knee arthroplasties (TKAs) were performed consecutively. Twenty-seven patellar clunk syndromes were identified in 25 patients. Insall-Salvati ratio, position of joint line, postoperative patellar height, and anterior-posterior position of tibial tray were measured. It was found that postoperative low-lying patella (P<.001) and anterior placement of tibial tray (P=.011) was associated with patellar clunk syndrome. Thirteen patients had bilateral TKAs of the same prosthesis (5 bilateral AMK knees and 8 bilateral Insall Burstein knees) but unilateral patellar clunk syndrome. The nonclunk sides were used as control for comparison with the clunk sides. The congruency and tilting of the patellar button in the skyline view were documented. It was observed that the congruency of the patellar button was less satisfactory in the clunk side (P=.019).     

The effect of quadriceps contraction during weight-bearing on four patellar height indices

The effect of weight-bearing on the height of the patellar using four radiological indices was studied in 25 healthy men using lateral radiographs of the knee in 30 degrees of flexion non-weight-bearing and weight-bearing. The position of the patella was quantified using the Insall-Salvati, the modified Insall-Salvati, the Blackburne-Peel and the Caton indices. The contraction of the quadriceps on weight-bearing resulted in statistically significant proximal displacement of the patella with all four indices studied. The mean Insall-Salvati index was 0.919 (sd 0.063) before and 1.109 (sd 0.042) after weight-bearing (p = 0.001), while the mean modified Insall-Salvati index was 0.734 (sd 0.039) before and 0.896 (sd 0.029) after weight-bearing (p = 0.041). Similarly, the Blackburne-Peel index was 0.691 (sd 0.09) before and 0.807 (sd 0.137) after weight-bearing (p = 0.012). The mean Caton index was 0.861 (sd 0.09) before and 0.976 (sd 0.144) after weight-bearing (p = 0.023). The effect of quadriceps contraction should be considered in clinical studies where the patellar position indices are reported.     

Open-wedge retro-tubercular tibial osteotomy: an innovating technique

Open-wedge tibial osteotomy for varus correction is a common orthopedic procedure. The rate of complications remains significant: loss of correction, nonunion, patellar infera... We propose a new open-wedge technique for tibial osteotomy which has several advantages: less risk of patella infera, improved bone healing, excellent mechanical stability. The osteotomy involves two cuts with an anterior portion ending distally to the tibial tubercle. This preserves the integrity of the patellar tendon and maintains contact between the proximal tibia and the tibial tubercle. Adjunction of an anteroposterior screw adds stability. The anterior plane of the osteotomy provides an excellent surface contact favoring bone healing. The posterior plane is the same as with a "classical" open-wedge osteotomy. The lateral cortical must always remain intact (hinge). The technique described here does not require any specific instrumentation and is compatible with most of the available osteosynthesis implants.