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.     

The early diagnosis and treatment of developmental patella infera syndrome

Developmental patella infera and associated arthrofibrosis after knee surgery require prompt recognition and treatment. The condition develops because of contracture of peripatellar tissues, fatpad tissues, and quadriceps weakness, and may rapidly progress to permanent patella infera and disabling patellofemoral arthrosis. Case studies for five patients with acute developmental patella infera are described. All patients required an early arthroscopic release of contracted tissues. To establish normal right to left patellar, vertical-height ratios, lateral roentgenograms were obtained in 202 normal knees (101 pairs). The data showed that although essentially no difference existed between right and left sides, large variations existed in the ratios from one individual to another (range, 0.75-1.46). Thus, the diagnosis of developmental patella infera requires comparison of patellar height ratios in the same knee or between knees in the same individual. A decrease in the vertical-height ratio of 11%-15%, depending on the method used, indicates developmental patella infera.     

进展性下位髌骨综合征

目的：报道临床所见的进展性下位髌骨综合征,探讨其病因、诊断,并介绍一种新的治疗方法。方法：本组病人共11例,均由膝关节手术或创伤引起。以膝关节僵硬和髌骨高度降低为主要特征。髌骨垂直高度系数（Linclau法）平均较对侧减少50．4％,Lysholm膝关节功能评分平均47．5分。采用健侧中1／3骨－髌腱－骨移植延长髌腱。结果：髌骨高度恢复正常,膝关节伸屈功能及Lysholm评分较术前显著改善。结论：膝关节手术及创伤是引起该综合征的直接原因,髌骨垂直高度系数较对侧显著减少是诊断该病的主要依据。以中1／3骨－髌腱－骨移植延长髌腱,可准确恢复髌骨原来高度,改善膝关节的功能。     

Patellar resurfacing reduces pain after TKA for juvenile rheumatoid arthritis

Influence of patellar resurfacing after knee replacement and the frequency of patella infera and its relation to the postoperative appearance of the knee pain were assessed in patients with juvenile rheumatoid arthritis. Seventy-seven total knee arthroplasties using the AGC prosthesis with nonconstrained components were done on 52 patients with a mean followup of 7.3 years (range, 3-13 years). Anterior knee pain was present in 14 of 30 patients (47%) with an unreplaced patella and in two of 18 patients (11%) with patella resurfacing. The patella was replaced in 18 patients (35%) and in 23 of 77 knees (30%). Neither revision surgery of implanted patellar components nor any later resurfacing of an unreplaced patella were done during the followup. Preoperatively using the Insall-Salvati ratio, the majority of knees (54 of 77) had a low-riding patella. Patella infera occurred commonly in patients with juvenile rheumatoid arthritis. No connection between patella infera and anterior knee pain was found.     

Observations on patellar height following opening wedge proximal tibial osteotomy

Patellar height and patellar ligament length were assessed pre- and postoperatively in 28 patients who underwent a medial opening wedge proximal tibial osteotomy for varus gonarthrosis. This procedure produced no significant change in patellar ligament length. Pre- and postoperative Insall-Salvati ratios were 0.96+/-0.12 and 0.97+/-0.15, respectively (P=.30). The Insall-Salvati ratio decreased in 29% of patients, and no patient experienced a decline >0.07. The distance between the patella and tibiofemoral joint line ("patellar height") decreased in 100% of patients. The mean Blackburne-Peel ratio declined from 0.75+/-0.13 to 0.53+/-0.15 (P<.001). Sixty-four percent of the postoperative Blackburne-Peel values satisfied the radiographic criterion for patella infera (Blackburne-Peel ratio <0.54). Whereas the loss of patellar height, historically associated with lateral closing wedge proximal tibial osteotomy, is a function of patellar ligament contracture, the decreased distance between the patella and the tibiofemoral joint line following medial opening wedge proximal tibial osteotomy is a function of joint line elevation. The high incidence of patella infera following medial opening wedge proximal tibial osteotomy may have deleterious effects on patellofemoral biomechanics or may complicate subsequent total knee arthroplasty.     

The length of the patellar tendon after unicompartmental and total knee replacement.

Patella infera may occur after reconstruction of the anterior cruciate ligament (ACL), high tibial osteotomy and total knee replacement (TKR). Restriction of movement of the knee and pain may result. Our aim was to compare the incidence and to assess the effects of patella infera after TKR and unicompartmental knee replacement (UKR). We reviewed radiographs of the knees of 84 patients who had had either TKR or UKR as part of a randomised, controlled trial The length of the patellar tendon was measured on serial radiographs taken before, at eight months and at five years after operation. There was no significant change in the length of the patellar tendon after UKR, but a significant reduction was observed after TKR. Five years after the operation, the shortening of the tendon had increased to a mean of 3.5 mm. Of the knees with TKR reviewed at five years, 34% developed patella infera, defined as 10% or more of shortening, compared with 5% of those with UKR. Shortening was greatest in those knees which had required a lateral release; in this subgroup the mean shortening was 7.2 mm. Shortening correlated with restriction of movement and pain in the knee. Our study has shown that patella infera develops in most patients after TKR with lateral release, and in approximately 25% of patients after TKR without this additional procedure. Patella infera rarely occurs after UKR. It is associated with restriction of movement and pain in the knee. It may be an effect of the more extensive exposure required to perform TKR and may, in part, explain the better clinical results of UKR.     

New technique for knee flexion contracture with patella infera using patellar tendon reconstruction combined with anterior capsular shift: a case report

A 24-year-old male presented with an open fracture of the left patella (Gustilo–Anderson grade III-A) and fracture of the left femoral lateral condyle, and subsequent patella alta suggesting rupture of the left patellar tendon. This initial injury was treated 6 months earlier in another hospital. He was referred because of limited knee motion and radiographs showed severe patella infera. By means of a combination of a contralateral BTB graft and soft tissue repair named anterior capsular shift, the knee contracture with patella infera was resolved successfully. All devices used in this article were approved by Organization of the Ministry of Health, Labourand Welfare in Japan.     

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.     

Patella alta and patella infera. Their etiological role in patellar dislocation, chondromalacia, and apophysitis of the tibial tubercle.

The Insall-Salvati method of assessing the position of the patella was applied to four groups of patients:normal patients, and those with dislocation of the patella, chondromalacia of the patella, and apophysitis of the tibial tubercle. The ratio of patellar length to tendon length was 1.0 in the normal patients, 0.8 in the patients with dislocations, 0.86 in those with chondromalacia, and 1.2 in those with apophysitis of the tibial tubercle. Patella alta may be an important cause of dislocating patella and of chondromalacia patellae. The significance of the patella infera found in the Osgood-Schlatter lesion may be one of either cause or effect.     

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.     

Arthrofibrosis and patella infera: a simple surgical solution. Preliminary report and literature review

Treatment of patella infera and arthrofibrosis after total knee replacement (TKR) remains an unsolved problem. Different options have been proposed: patellectomy, proximal transposition of tibial tuberosity, distalization of the femoral component, arthroscopic and open debridment of intraarticular fibrosis. Individual predisposition, mechanical irritation due to technical errors and an aggressive rehabilitation program have been all related as predisposing or causative factors. We present one patient with patella baja and arthrofibrosis with progressive retraction of patellar tendon treated with open arthrolysis and resection of the distal third of the patella in order to lengthen the tendon and prosthetic resurfacing of the remaining two proximal thirds of the patella. Insall-Salvati, Blackburne and Caton indexes were measured from post-operative X-rays after primary surgery to assess that the cause was not an initial component malposition, before and after our revision procedure.     

Long-term outcome of surgically-treated habitual patellar dislocation in children with coexistent patella alta. Minimum follow-up of 11 years

We retrospectively reviewed the operative treatment carried out between 1988 and 1994 of eight patients with habitual patellar dislocation. In four the condition was bilateral. All patients had recurrent dislocation with severe functional disability. The surgical technique involved distal advancement of the patella by complete mobilisation of the patellar tendon, lateral release and advancement of vastus medialis obliquus. The long-term results were assessed radiologically, clinically and functionally using the Lysholm knee score, by an independent observer. The mean age at operation was 10.3 years (7 to 14) with a mean follow-up of 13.5 years (11 to 16). One patient required revision. At the latest follow-up, all patellae were stable and knees functional with a mean Lysholm knee score of 98 points (95 to 100). In those aged younger than ten years at operation there was a statistically significant improvement in the sulcus angle at the latest follow-up (Student's t-test, p = 0.001). Two patients developed asymptomatic patella infera as a late complication. This technique offers a satisfactory treatment for the immature patient presenting with habitual patellar dislocation associated with patella alta. If performed early, we believe that remodelling of the shallow trochlea may occur, adding intrinsic patellofemoral stability.     

Post impingement in posterior stabilised total knee arthroplasty

Posterior stabilised implants are a well-proven treatment for patients requiring primary total knee arthroplasty. Concerns about the posterior stabilised (PS) design have been raised and recent studies suggest that the post-cam articulation can be an additional source of polyethylene wear debris. In this study, the authors report impingement of the tibial post against the patellar component in deep flexion in posterior stabilised total knee arthroplasty. Their data suggest that "post impingement" is associated with a raised joint line, patella infera, too anterior placement of the tibial component and a smaller femoral component size. "Post impingement" may lead to extensor mechanism problems and additional polyethylene wear and therefore may affect the longterm functional results of posterior stabilised total knee arthroplasty.     

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).     

The sulcus angle and malalignment of the extensor mechanism of the knee

Anterior knee pain due to dysplasia of the extensor mechanism is common. We have studied 137 knees (103 patients) in order to identify a rapid and reproducible radiological feature which would indicate the need for further analysis. Overall, 67 knees (49%) had at least one radiological abnormality; 70 (51%) were considered normal. There were five cases of Dejour type-3 dysplasia of the femoral trochlea, nine of type-2 and 12 of type-1. There were 49 cases of patella alta and five of patella infera. Four knees had an abnormal lateral patellofemoral angle (patellar tilt), and in 15 knees there was more than one abnormality. Classification of trochlear dysplasia was difficult and showed poor reproducibility. This was also true for the measurement of the lateral patellofemoral angle. Patellar height was more easily measured but took time. The sulcus angle is an easily and rapidly measurable feature which was reproducible and was closely related to other features of dysplasia of the extensor mechanism. The finding of a normal sulcus angle suggested that seeking other radiological evidence of malalignment of the extensor mechanism was unlikely to reveal additional useful information. The severity of other features of dysplasia of the extensor mechanism correlated with increasing sulcus angle.     

Patellar tendon rupture repair using Dall-Miles cable

Ten patients underwent patellar tendon repair with end-to-end suture technique and medial and lateral retinacular repair, as well as reinforcement with a Dall-Miles cable through the patella and tibial tubercle. The cable was tensioned at 60 degrees of flexion to allow immediate range of motion to at least 100 degrees of flexion and to protect the repair from undue tension while healing. Accurate tendon length was obtained from a lateral radiograph of the noninvolved knee in 60 degrees of flexion. Patients were allowed to bear full weight as tolerated postoperatively. A knee immobilizer was worn for approximately 2 weeks when adequate muscular control of the leg was attained. The cable was removed 6-8 weeks postoperatively, at which time range of motion equal to the opposite extremity was sought. Full extension was obtained by 1 week postoperatively. Average postoperative knee flexion was 88 degrees at 2 weeks, 112 degrees at 1 month, 133 at 3 months, and 138 degrees at 6 months compared to flexion of 141 degrees in the noninvolved knee. Mean quadriceps muscle strength 1 year postoperatively was 72%+/-11% of the noninvolved leg. No patient had patella infera or rerupture after surgery. Repair of a patellar tendon rupture with end-to-end techniques reinforced with a Dall-Miles cable allows immediate rehabilitation without the need for prolonged immobilization. This technique allows restoration of full range of motion early postoperatively and enables patients to regain adequate quadriceps strength.     

Patellar surface strain

We measured longitudinal surface strains on the anterior patella at controlled simulated quadriceps loads, quadriceps angles, and knee flexion angles. We studied both the natural patella and patellas resurfaced with domed, bifaceted, and metal backed polyethylene components. Twelve matched pairs of fresh human cadaver knee specimens were tested. Midanterior longitudinal patellar strains were greatest at knee flexion angles at 45 to 60 degrees of knee flexion. Alterations in quadriceps angle medially and laterally did not decrease recorded strain values significantly. Polyethylene patellar prostheses increased patellar strains but a bifaceted component or "total contact" design minimized this effect. Metal support for the prosthetic patella decreased the recorded surface strains. This study of patellar surface strain at the three midline locations provides experimental results that may prove useful for design and validation of analytic models of the patella. The study also suggests that patellar surface strain measures may provide a method for evaluating the effects of patellar prosthesis design and resurfacing procedures.     

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.     

Effects of patellar position and defect healing on in vitro stifle joint kinematics following removal of the central one‐third of the patellar tendon in an ovine model

Harvest of the central one‐third of the patella tendon (PT) is routinely performed for anterior cruciate ligament reconstruction (ACLR). Patella infera may ensue. In this study we unilaterally resected the central one‐third of the PT in 20 sheep, without reconstructing or defunctionalizing the native ACL, and examined the effects at 3, 6, 12, and 24 weeks postoperatively on PT length, histological appearance of the donor defect and in vitro stifle joint kinematics. Mean length increases (p > 0.263) in the operated tendons of 0.3%, 2.8%, 0.5%, and 2.4% were observed at 3, 6, 12, and 24 weeks. A significant proximal shift of the patella correlated well with a mean 2.35° retardation of patellar flexion (r = 0.440, p = 0.001). A mean net 4.9° decrease in medial patellar tilt was also observed (p < 0.001), but was not coupled with changes in tibial rotation. Donor defect tissue showed a distinct progression of healing with time, remodeling from dense scar tissue at 3 weeks to bundles of well‐organized collagen enveloped by vascularized loose connective tissue at 24 weeks but was not associated with the restoration of kinematics. These results suggest that resection of the central one‐third of the PT and leaving the defect open in the ovine stifle joint may be associated with increased PT length and changes in patellar kinematics which do not recover 6 months postoperatively. The lack of patella infera may render this animal model unsuitable for the interpretation of joint kinematics following PT resection for human ACLR. © 2010 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 29:572–581, 2011     

Model predictions of increased knee joint loading in regions of thinner articular cartilage after patellar tendon adhesion

Patellar tendon adhesion is a complication from anterior cruciate ligament (ACL) reconstruction that may affect patellofemoral and tibiofemoral biomechanics. A computational model was used to investigate the changes in knee joint mechanics due to patellar tendon adhesion under normal physiological loading during gait. The calculations showed that patellar tendon adhesion up to the level of the anterior tibial plateau led to patellar infera, increased patellar flexion, and increased anterior tibial translation. These kinematic changes were associated with increased patellar contact force, a distal shift in peak patellar contact pressure, a posterior shift in peak tibial contact pressure, and increased peak tangential contact sliding distance over one gait cycle (i.e., contact slip). Postadhesion, patellar and tibial contact locations corresponded to regions of thinner cartilage. The predicted distal shift in patellar contact was in contrast to other patellar infera studies. Average patellar and tibial cartilage pressure did not change significantly following patellar tendon adhesion; however, peak medial tibial pressure increased. These results suggest that changes in peak tibial cartilage pressure, contact slip, and the migration of contact to regions of thinner cartilage are associated with patellar tendon adhesion and may be responsible for initiating patellofemoral pain and knee joint structural damage observed following ACL reconstruction. © 2011 Orthopaedic Research Society Published by Wiley Periodicals, Inc. J Orthop Res 29: 1168–1177, 2011