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At least 199 records · Page 11Linked to original sources
PubMed2005

Eversion or subluxation of patella in soft tissue balancing of total knee arthroplasty? Results of a cadaver experiment.

Correct postoperative leg alignment and stability of total knee prosthesis over the full range of movement are critical factors for successful TKA. This is achieved by correct implantation of prosthesis and soft tissue handling. However, the surgical approach and how to displace the patella are still controversial. We have carried out a cadaver study looking at the effect of patella eversion or subluxation on limb axis alignment during balancing of the knee in three different standard surgical approaches; subvastus, midvastus, or medial parapatellar. For each approach, five knees were studied. Leg alignment was visualised by the Ci CT-free DePuy/BrainLAB navigation system. Using a navigation system alignment was determined in the AP axis in both extension and 90 flexion, with the patella everted as well as subluxated. Eversion of the patella gave a more valgus axis reading than subluxation in both extension 0.58 (SD: 0.03, range 0.54 -0.60 ) and 90 flexion 0.48 (SD: 0.11, range 0.38 -0.60 ). The effect was greatest using the medial paraptellar approach. Surgeons should be aware that everting the patella influences the AP alignment when soft tissue balancing in total knee replacement.

Arthroplasty, Replacement, Knee↗
PubMed2006

Unicortical transverse osteochondral fracture of the patella: a case report.

Chondral lesions are relatively common and they usually occur as a result of high energy trauma. Chondral fractures of the patella ordinarily occur during an acute dislocation of the patella. Patellar chondral fractures without either a dislocation or a patella fracture are extremely rare. We have treated a 25-year-old male who had a unicortical transverse osteochondral fracture of the patella without a dislocation which was produced by high energy trauma. Chondral fractures of the patella are often overlooked because they are difficult to detect on plain radiographs. A persistent cartilaginous irregularity from either a chondral or osteochondral fracture may lead to the development of secondary osteoarthrosis. In this case, restoration of the articular surface was achieved by elevation of the compressed osteochondral fragment. This case demonstrates that understanding the mechanism of injury can be helpful in the treatment of osteochondral lesions.

Accidental Falls↗
PubMed2003

Acute lateral dislocation of the patella: correlation of ultrasound scanning with operative findings.

Acute lateral dislocation of the patella has been associated with disruption of the medial restraints of the patella. Following non-operative management there is a re-dislocation rate of up to 44%. The purpose of this study was to test whether sonography is a reliable method of assessing the medial retinaculum after acute dislocation of the patella. Ten patients following acute patellar dislocation had an ultrasound scan (USS) performed by an experienced musculoskeletal radiologist. Each patient subsequently had an examination under anaesthetic, arthroscopy, and repair of the ruptured structures. The ultrasound reports were compared to the surgical findings to determine the accuracy of this investigation. USS located deficiencies in the ligamentous attachments to the medial border of the patella and the presence of avulsed bony fragments, all of which were confirmed at operation. The sonographic diagnosis of haematoma or torn fibres in the vastus medialis obliquus (VMO) corresponded with our operative findings. The most significant findings were the correlation of free fluid around the medial collateral ligament (MCL) with avulsion of the femoral attachment of the medial patellofemoral ligament (MPFL) and the presence of avulsed fragments of bone from the medial border of the patella.

Adolescent↗
PubMed1993

Two cases of dorsal defect of the patella with arthroscopically visible cartilage surface perforations.

Dorsal defect of the patella is an approximately 1-cm, circular, radiolucent, well-marginated benign lesion invariably located in the superlateral aspect of the patella. Only approximately 50 cases have been described in the world literature, of which < 10 cases have been studied histologically. We report two patients with bilateral, virtually symmetrical, dorsal defects of the patella and describe the arthroscopic and histologic findings. Case 1 was a 14-year-old girl and case 2 was a 35-year-old man. Cartilage perforations were seen via arthroscopy on the cartilage surface of both knees. The pathophysiology of this disorder remains to be clarified, although van Holsbeeck et al. proposed that vastus lateralis traction injury in the ossification process of the patella may be involved, as in the case of bipartite patella. The present arthroscopic and histological findings support this hypothesis.

Adolescent↗
PubMed1999

Ultrasound velocity and attenuation in relation to maximum trabecula stress in the patella.

The ultrasound velocity and attenuation were examined in 16 sets of human patellae. The average ultrasound velocity of patella was shown to be greater in the superior/inferior direction than in the anterior/posterior and medial/lateral directions. The distribution of bone mineral density (BMD) was also examined. The BMD of the patella varied with location. BMD values were largest at the superior and lateral regions and decreased inferiorly and medially. A two-dimensional finite element analysis was performed on each patella. The maximum von Mises stress occurred along the cortical shell on the non-articular surface. The trabecular von Mises stress existed in the posterior region of the patella. Correlation study showed that patellar BMD was significantly associated with each of three directional ultrasound velocities. The relationship between BMD and ultrasound attenuation was not significant. It was also found that the ultrasound velocity and attenuation were not significantly correlated with the maximum von Mises stress.

Aged↗
PubMed2003

Orthopaedic crossfire--All patellae should be resurfaced during primary total knee arthroplasty: in opposition.

After more than 20 years of debate, the decision on whether to resurface the patella in primary total knee arthroplasty (TKA) remains controversial. Laboratory testing suggests that performing a TKA alters knee kinematics. Every study to date has suggested that kinematics are more abnormal when the patella is resurfaced than when it is retained. In addition, patellofemoral contact areas are higher and contact stresses are lower with the native patella compared with the resurfaced patella after TKA. Virtually every clinical study of bilateral knee arthroplasty in which one patella has been resurfaced and the other has not has shown either equivalent results or a preference for the unresurfaced side. Laboratory and clinical data indicate that not resurfacing the patellar is a viable if not preferable option in most TKA patients.

Arthroplasty, Replacement, Knee↗
PubMed2003

[Computed tomography of the patellofemoral alignment after arthroscopic reconstruction following patella dislocation].

PURPOSE: To evaluate the diagnostic impact of different CT-based measurements to analyze the patellofemoral alignment after arthroscopic reconstruction in patients with patella dislocation. MATERIALS AND METHODS: In 18 patients with dislocation of the patella, CT of the patellofemoral joint was performed after arthroscopic reconstruction. Various methods recommended in the literature were used to analyze the structure and the alignment of the patellofemoral joint with a relaxed quadriceps muscle. Axial CT scans were taken in four different knee flexion angles (15 degrees, 30 degrees, 45 degrees, 60 degrees ). RESULTS: After arthroscopic stabilization in patients with patella dislocation, only the lateral patellofemoral angle (15 degrees and 30 degrees knee flexion) and the congruence angle (15 degrees knee flexion) showed significant differences between the CT-measurements in the normal and the operated group. The differences of the remaining mean values were not significant due to a high standard deviation. With increasing flexion of the knee, the differences between the normal and the dislocation group almost disappeared. Only the lateral patellofemoral angle, the patella tilt and the lateral patella shift revealed differences between the normal and the group with recurrent dislocation in every degree of knee flexion. With increasing knee flexion above 30 degrees and especially at 60 degrees, the majority of the measured values returned to the normal range. CONCLUSIONS: For CT-measurements of the patellofemoral joint after arthroscopic stabilization, the patellofemoral angle and the congruence angle seemed to be most useful. The measurements of the patellofemoral joint should be taken in various degrees of knee flexion.

Adolescent↗
PubMed1995

Decreased torque and electromyographic activity in the extensor thigh muscles in chondromalacia patellae.

The alterations in thigh muscle properties of chondromalacia patellae patients during isometric and dynamic endurance tests were studied using a variokinetic knee testing system linked to surface EMG. A total of 41 patients (chondromalacia group) with arthroscopically certified chondromalacia of the patella were studied. The control group consisted of 31 healthy adult volunteers with no history of knee pain or trauma. Peak torque values were 21% (p < 0.01) and force output values 25% (p < 0.05) lower on the symptomatic side of the chondromalacia group than in the control group. The decrease in the ratio between integrated EMG (IEMG) and measured force were found in all parts of the quadriceps femoris muscle in patients with chondromalacia of the patella in isometric extension. No change in the normalized IEMG levels of the thigh muscles were found between chondromalacia patients and controls in dynamic endurance test. The severity of the chondromalacia of the patella did not affect the level of electromyographic activation in thigh muscles. The ratio of normalized EMG levels of vastus medialis and vastus lateralis did not differ between the groups. The present study showed that chondromalacia patellae patients have reduced force and electromyographic activation levels of quadriceps femoris muscle. Especially, the explosive strength of the quadriceps femoris muscle is reduced.

Adolescent↗
PubMedDate not supplied

Surgical treatment of congenital dislocation of the patella.

Eleven patients with 17 involved knees were surgically treated for congenital dislocation of the patella between 1978 and 1993. Ten patients with 13 involved knees followed up for a minimum of 2 years postoperatively composed the study group. Six patients had both involved knees operatively treated. In four patients, congenital dislocation of the patella was associated with a recognizable syndrome. All patients had fixed, painful lateral dislocation of the patella that could not be reduced. The average age at presentation was 7 years and 9 months (range, 2 months to 15 years). All patients underwent an extensive procedure including lateral release and advancement of the vastus medialis obliquus. Skeletally immature children underwent medial transfer of the entire patellar tendon. Skeletally mature patients underwent medial transfer of the tibial tubercle. Ten patients with 13 involved knees were followed up for > or = 2 years. Mean follow-up was 5.1 years (range, 1-17.5). At last follow-up, all patients reported a marked increase in activity tolerance and relief of pain. Average extension lag improved from 15 degrees before to 2 degrees after surgery. One superficial wound infection occurred; no patient developed a deep infection. One peroneal neurapraxia occurred but resolved with observation. Redislocation of the patella occurred in the immediate postoperative period in one patient. Operative treatment of congenital dislocation of the patella can predictably improve knee function when all aspects of the complex pathologic anatomy are addressed.

Adolescent↗
PubMedDate not supplied

Extensile exposure of comminuted patella fractures using a tibial tubercle osteotomy: results of a new technique.

OBJECTIVE: To evaluate the clinical results of comminuted patella fracture fixation after an extensile surgical approach by using a tibial tuberosity osteotomy. DESIGN: Prospective, clinical. PATIENTS: Six knees with displaced comminuted patella fractures had stable internal fixation after an osteotomy of the tibial tubercle. All had immediate postoperative continuous knee motion and were followed for an average of thirty-one months (minimum of eighteen months). OUTCOME MEASURES: Time to clinical and radiographic union, Hospital for Special Surgery (HSS) Knee Scores and comparisons with literature cohort studies. RESULTS: Clinical union of the osteotomy occurred at an average of eight weeks (range 6 to 12 weeks) and of the patella fractures at an average of eleven weeks (range 8 to 21 weeks). There was no radiographic evidence of osteotomy displacement, fracture implant loosening, migration, or failure. All patients had clinical residua, which included loss of motion, thigh muscle atrophy, and barometric complaints. HSS Knee Scores averaged 75 points with four good, one fair, and one poor result. These results were comparable to those of previously published reports of ablative surgery for this type of fracture. CONCLUSION: Comminuted patella fractures are severe injuries that usually result in some lingering morbidity. Internal fixation preserves bone stock, which facilitates future reconstructive procedures. The described tibial tuberosity osteotomy, patella eversion technique of fracture exposure improved visualization and reduction of the articular surface. The osteotomy healed in all cases and did not adversely affect the clinical results.

Adolescent↗
PubMed2003

Treatment of the patella at reimplantation for septic total knee arthroplasty.

The results of treatment of the patella at the time of aseptic revision of a total knee arthroplasty (TKA) have been better with resurfacing of the patella than other modes of treatment such as leaving a bony shell. Treatment of the patella at the time of reimplantation of a TKA has not been addressed in prior studies. The ability to resurface the patella will be determined by the amount of bone remaining, integrity of the patella, vascularity, the location of the joint line, and soft tissue coverage for wound closure. The current review addresses the technique of patellar resurfacing and patellar bone defect treatment at the time of reimplantation of a TKA.

Arthroplasty, Replacement, Knee↗
PubMed2005

Failure to resurface the patella during total knee arthroplasty may result in more knee pain and secondary surgery.

UNLABELLED: Resurfacing the patella during primary total knee arthroplasty is controversial. The objective of this meta-analysis was to evaluate the outcome of total knee arthroplasty with or without resurfacing of the patella with particular attention to patient satisfaction, incidence of anterior knee pain, patellar complications, and the need for secondary operations. Computerized databases were searched for citations and published randomized clinical trials relevant to patellar resurfacing from 1966-2003. Of 158 citations identified as related to patellar resurfacing during total knee arthroplasty, 14 articles met all inclusion criteria for this study. The incidence of anterior knee pain was greater in knees with nonresurfaced patellas. Secondary resurfacings for anterior knee pain was needed in 8.7% of nonresurfaced knees. No difference in reported complications existed. Total knee arthroplasty resulted in improvement of functional outcome regardless of whether the patella was resurfaced. Based on the results of this meta-analysis, nonresurfacing of the patella during primary total knee arthroplasty is likely to result in a greater incidence of anterior knee pain, the need for secondary resurfacing in almost one in 10 patients, and possibly less patient satisfaction. LEVEL OF EVIDENCE: Therapeutic study, Level IV (case series). See the Guidelines for Authors for a complete description of levels of evidence.

Aged↗
PubMed2005

Revision of the patella with deficient bone using a biconvex component.

UNLABELLED: Revision surgery on a failed patellar component can be difficult because of deficient residual bone that may compromise the functional outcome of the revision. We reviewed 20 knees in 20 patients in whom the residual patellar bone was less than 10 mm at the time of revision and used the Genesis Biconvex Patella implant to reconstruct the patella. The patients were followed up for an average of 34 months (range, 24-65 months), and were followed up clinically and radiographically by Knee Society criteria. Patellar revisions and complications were noted and standard radiographic studies to ascertain radiolucent lines and patella/patellar component thickness were evaluated. The Knee Society Scores improved from an average of 45 points to 89 points. Function scores improved from an average of 47 points to 65 points. None of the patients has required revision surgery and no patellar fractures have been seen. Radiographs showed complete lucencies at the cement-bone interface in two knees. The mean residual central patella bone thickness was 6.5 mm and the average postoperative composite thickness was 14.5 mm. The data indicate that the use of the Genesis Biconvex Patella implant is a satisfactory method of treating revision of the patella when there is major bone deficiency. LEVEL OF EVIDENCE: Retrospective study, Level IV-1 (case study). See the Guidelines for Authors for a complete description of levels of evidence.

Adult↗
PubMed2004

Associations of patella lead with polymorphisms in the vitamin D receptor, delta-aminolevulinic acid dehydratase and endothelial nitric oxide synthase genes.

A cross-sectional analysis was performed to evaluate associations of polymorphisms in the vitamin D receptor (VDR), delta-aminolevulinic acid dehydratase (ALAD), and endothelial nitric oxide synthase (eNOS) genes with patella lead concentrations in 652 lead workers in the Republic of Korea. There was a wide range of patella lead (from below detection limit to 946 microg Pb/g bone mineral), with a mean (standard deviation) of 75.2 (101.0). There were no associations of ALAD or eNOS genotypes with patella lead, but workers with the VDR B allele had significantly (P value < 0.05) higher patella lead (on average, 25% or approximately 6.6 microg Pb/g bone mineral) than lead workers with the VDR bb genotype. There was evidence that the relation between age and patella lead was modified by both the VDR and eNOS genotypes.

Adult↗
PubMed2005

Associations of patella lead and other lead biomarkers with renal function in lead workers.

OBJECTIVE: We sought to compare associations of patella lead, which may represent a unique cumulative and bioavailable lead pool, with other lead measures in models of renal function. METHODS: Renal function measures included blood urea nitrogen, serum creatinine, measured and calculated creatinine clearances, and urinary N-acetyl-beta-D-glucosaminidase (NAG) and retinol-binding protein. RESULTS: In 652 lead workers, mean (SD) blood, patella, and tibia lead were 30.9 (16.7) microg/dL, 75.1 (101.1) and 33.6 (43.4) microg Pb/g bone mineral, respectively, and were correlated (Spearman's r = 0.51-0.74). Patella lead was associated (P < 0.05) with NAG in all lead workers. In models of effect modification by age, higher patella lead also was associated with higher serum creatinine in older participants. Similar associations were observed for blood and tibia lead. CONCLUSIONS: Associations between patella lead and adverse renal outcomes were not unique; this may be due, in part, to high correlations among the lead biomarkers in this study.

Adult↗
PubMed2004

Reducing the lateral force acting on the patella does not consistently decrease patellofemoral pressures.

BACKGROUND: Extensor mechanism procedures that decrease the lateral component of the patellar tendon or quadriceps force acting on the patella do not consistently reduce pain. HYPOTHESIS: Patellofemoral treatments do not consistently decrease patellofemoral pressures because of variations in the moments acting on the patella. STUDY DESIGN: Computer simulation study. METHODS: Computational models of 4 knees were constructed to characterize the patellofemoral pressure distribution during simulated squatting from 40 degrees to 90 degrees. The knees were given an initial Q angle of 25 degrees. Patellofemoral treatments were simulated by increasing the percentage of the quadriceps force applied by the vastus medialis by 50% and by medializing the tibial tuberosity to decrease the Q angle to 15 degrees. RESULTS: Decreasing the Q angle caused a larger decrease in the lateral component of the force applied by the quadriceps and patellar tendon than did increasing the force applied by the vastus medialis and, therefore, was more effective at decreasing patellofemoral pressures and the force needed to resist lateral subluxation. Both treatments also decreased the moments acting to rotate the distal patella laterally and tilt the patella laterally during flexion. Variations in these moments increased patellofemoral pressures for some knees. CONCLUSIONS: Treatments that reduce patellofemoral subluxation can have an unexpected influence on patellofemoral pressures because of the moments acting on the patella. CLINICAL RELEVANCE: Extensor mechanism procedures that restore patellofemoral stability may not provide pain relief.

Biomechanical Phenomena↗
PubMed2005

Bilateral recurrent discloation of the patella associated with below knee amputation: a case report.

BACKGROUND: Recurrent dislocation of the patella in patients with below knee amputation is a known entity. Abnormally high-riding patella (patella alta) and medial patellofemoral ligament insufficiency in these patients predisposes them to patellar instability. The established treatment of this problem is surgical realignment. CASE PRESENTATION: A 25 year old male patient with bilateral below knee amputation presented with bilateral recurrent dislocation of the patella while walking on knees on uneven ground. Clinical and radiographic studies showed patella alta. A simple shoe modification was used to treat this patient. CONCLUSIONS: A simple shoe modification can be used to treat such a condition which is otherwise treated surgically.

Adult↗
PubMed1978

Patella alta and chondromalacia.

The Insall-Salvati method of determining the position of the patella by radiography was employed in fifty-one patients with chondromalacia patellae that had been proved at arthrotomy. There was no definite relationship between chondromalacia patellae and patella alta. There was, however, a highly significant statistical difference between the ratio of the length of the patella to that of the patellar tendon in normal men and women.

Adolescent↗