Patellar stress fracture: a complication of knee joint arthroplasty without patellar resurfacing

A case of patellar stress fracture after total knee arthroplasty in a man with gout and previous osteonecrosis of the tali is reported. The combination of fat pad excision and lateral release causing disruption to the patellar blood supply during primary total knee arthroplasty resulted in the development of a patellar fracture. Avascular necrosis, caused by gout, may form part of the pathogenesis.     

Total Knee Arthroplasty Combined With Medial Patellofemoral Ligament Reconstruction for Osteoarthritic Knee With Preoperative Valgus Deformity and Chronic Patellar Dislocation

We report a challenging case of a 44-year-old woman who had osteoarthritis in the lateral compartment of her right knee with severe valgus deformity and chronic lateral patellar dislocation. Total knee arthroplasty was performed for the knee. However, persistent patellar dislocation remained during the surgery; and therefore, medial patellofemoral ligament (MPFL) reconstruction was additionally performed at the time of the surgery. Stable patellar tracking was obtained after the MFPL reconstruction; and during the 2-year follow-up, her knee functioned well, and no recurrent patellar dislocation was observed. This clinical case indicates the usefulness of MPFL reconstruction for obtaining stable patellar tracking during total knee arthroplasty when a tendency for lateral patellar dislocation remains.     

Osteonecrosis of bipartite patella following total knee arthroplasty without lateral release

We present a case of osteonecrosis of bipartite patella occurring after total knee arthroplasty using medial parapatellar approach without lateral retinacular release in osteoarthritic knee of a 66 year-old-male. The surgery was performed using traditional technique with medial parapatellar approach and patella was resurfaced. Patella was everted during surgery. There was no event during follow-up period after surgery. Range of motion of the knee was 135° without flexion contracture. Eight months after the surgery, patella was fragmented and resorbed on the radiographs which was consistent with osteonecrosis. The patient showed extension limitation of 30° with no pain. Patellar osteonecrosis has been rarely reported after total knee arthroplasty with lateral retinacular release. However, there was no report of patellar osteonecrosis after total knee arthroplasty without lateral retinacular release. Caution should be taken about patellar osteonecrosis in case of bipartite patella even though lateral retinaculum is preserved during total knee arthroplasty.     

Lateral patellar burnishing in total knee arthroplasty following medialization of the patellar button

This case report describes a total knee revision necessitated by painful contact between the exposed lateral facet of the patella and the femoral component. Pain was resolved following repositioning and enlarging the patellar component. The clinical significance of this report is that the contemporary practice of medializing the patellar component to improve patellar tracking should be performed in moderation to avoid overexposure of the lateral patella. In the setting of persistent anterior knee pain following total knee arthroplasty, the etiology of the pain may be identified as contact between the patellar and femoral component on the sunrise radiograph.     

Mesh expansion release of the lateral patellar retinaculum during total knee arthroplasty

BACKGROUND: Release of the lateral patellar retinaculum can be used to treat patellofemoral instability and to balance the extensor mechanism during knee replacement operations. However, conventional lateral release disrupts the integrity of the lateral knee capsule, may damage the blood supply to the patella, and is associated with several other potential complications. Mesh expansion release of the lateral patellar retinaculum was developed to achieve the goal of lateral release and to reduce the potential for postoperative morbidity. METHODS: Thirteen consecutive knees in eleven patients were treated with mesh expansion lateral release during a total knee arthroplasty and were evaluated after a minimum duration of follow-up of two years. The mesh release technique consisted of multiple, longitudinal, parallel 5 to 10-mm stab incisions to mesh and expand the lateral patellar retinaculum and thereby medialize the patella in the trochlear groove of the femoral implant. RESULTS: Mesh expansion lateral release balanced the extensor mechanism in each knee, maintained the mechanical integrity of the lateral capsule, and avoided disruption of the lateral genicular blood supply to the patella. After a minimum duration of follow-up of two years, no complications had been noted in association with mesh expansion lateral release. CONCLUSION: Mesh expansion release of the lateral patellar retinaculum effectively balanced the patellofemoral joint during total knee arthroplasty, maintained the integrity of the lateral capsule, and preserved the lateral genicular blood supply.     

Long-term changes of the nonresurfaced patella after total knee arthroplasty

BACKGROUND: The most common complications of total knee arthroplasty involve the patellofemoral joint. However, the long-term fate of the nonresurfaced patella after total knee arthroplasty has seldom been reported. The purpose of this study was to evaluate the long-term changes of the nonresurfaced patella after total knee arthroplasty. METHODS: We retrospectively evaluated the nonresurfaced patella in 227 knees (181 patients) at an average of 8.5 years after total knee arthroplasty. Functional results were correlated with radiographic changes, and risk factors leading to abnormal changes of the patella were analyzed. RESULTS: Preoperatively, 186 (82%) of the patellae tracked centrally, thirty-nine (17%) displaced or tilted laterally, and two (1%) subluxated laterally. At the time of the latest follow-up, 133 (59%) of the patellae still tracked centrally with preservation of the cartilage thickness, fifteen (7%) showed early lateral tilt, sixty-eight (30%) had progressive loss of lateral cartilage thickness with lateral tilt and/or displacement, seven (3%) had progressed to lateral subluxation, and four (2%) tilted medially. An abnormal patellofemoral joint did not affect the knee and functional scores (p = 0.90 and 0.89, respectively). However, symptoms such as difficulty rising from a chair or reluctance to use the involved lower limb while climbing stairs were noted. Preoperative patellar maltracking was identified as the only risk factor leading to postoperative patellar abnormalities (relative risk, 2.7; 95% confidence interval, 2.21 to 3.30; p = 0.003). CONCLUSIONS: At the time of follow-up, at an average of 8.5 years, patellar tracking and the patellofemoral joint remained normal after approximately 60% of the total knee arthroplasties performed without resurfacing of the patella. Progressive degenerative changes of the nonresurfaced patella (mainly on the lateral facet) and patellar maltracking were the most common abnormal radiographic changes. Patients with preoperative patellar maltracking were at risk for the development of these changes and clinical symptoms. Resurfacing of the patella during total knee arthroplasty may benefit such patients.     

Scintigraphic assessment of patellar viability in total knee arthroplasty after lateral release

To what extent lateral retinacular release done in total knee arthroplasty compromises patellar viability has been debated. This study is a prospective study to assess patellar viability using Technetium-99m methylene diphosphate (Tc-99m MDP) scintigraphy. Between 2005 and 2006, 59 patients (72 knees) who underwent primary total knee arthroplasty were studied, of which 36 required lateral release. All patients underwent regional bone scan using Tc-99m MDP before and 1 to 3 weeks after the surgery. Two nuclear medicine consultants using both qualitative and quantitative assessment interpreted the scans independently. Fourteen knees with lateral release showed scintigraphic signs of hypovascularity in the early postoperative period that normalized in 8-week postoperative period. This study documents the greater incidence of transient patellar hypovascularity associated with lateral release.     

Lateral patellar chamfer in total knee arthroplasty

Derangement of the anterior compartment of the knee can cause patellofemoral dysfunction in up to 50% of secondary surgeries after total knee arthroplasty. A technique of patellar chamfering is described that can minimize the risk of anterior knee pain from lateral patellar impingement without compromising bone stock for future operations.     

The effect of stuffing the patellofemoral compartment on the outcome of total knee arthroplasty

BACKGROUND: The effect of so-called stuffing of the patellofemoral compartment at the time of total knee arthroplasty (that is, increasing the anterior patellar displacement, the anteroposterior femoral size, or the combined anteroposterior patellofemoral size) has not been well studied. The purpose of the present study was to evaluate the effect of stuffing the patellofemoral compartment on the outcome of primary total knee arthroplasty. METHODS: A retrospective review of 1100 primary total knee arthroplasties that had been performed in 1997 and 1998 was conducted. Eight hundred and thirty arthroplasties (75.5%) met the diagnostic and minimum two-year follow-up criteria for inclusion in this report. Radiographic measurements were made to determine preoperative and postoperative anterior patellar displacement, anteroposterior femoral size, combined anteroposterior patellofemoral size, anterior femoral offset, and posterior femoral offset. Regression analysis was performed to determine the effects of changes in these variables on the range of motion, the Knee Society Knee Score, the Knee Society Function Score, the Knee Society Pain Score, and the rate of lateral retinacular release. RESULTS: Preoperative to postoperative changes in anterior patellar displacement, anteroposterior femoral size, combined anteroposterior patellofemoral size, anterior femoral offset, and posterior femoral offset had no clinically meaningful effect on the range of motion of the knee or on any of the Knee Society scores. Increases in anterior patellar displacement were associated with a lower probability of the need for a lateral retinacular release. Increases in measured anteroposterior femoral size were associated with a higher probability of the need for lateral release. Even when combined, however, these relationships explained only 10.1% of the observed variance in the need for lateral retinacular release. Moreover, analyses indicated that patient gender, large as opposed to medium patellar size, and absolute femoral component size influenced the likelihood of lateral release more than did anterior patellar displacement and measured anteroposterior femoral size. CONCLUSIONS: Our findings do not support the widely held belief that stuffing of the patellofemoral joint results in adverse outcomes after total knee arthroplasty. Furthermore, the need for lateral release appears to be multifactorial and likely involves a more complex set of factors. Thus, without evidence of other identifiable causes of failure, we do not recommend revision for the treatment of pain of an overstuffed knee joint.     

Lateral patellar contact after total knee arthroplasty: an analysis of the effects on postoperative pain and outcome

Although medialization of the patellar component during primary total knee arthroplasty (TKA) has been advocated for biomechanical reasons, this can lead to lateral patellar contact with the femoral component. Using blinded radiographic evaluations, we evaluated 980 consecutive primary TKAs performed from 1997 to 1998. The prevalence of lateral patellar contact in this series was found to be 46.1%. Lateral patellar contact was not correlated with significant differences in our measures of outcome (knee score [P = .1066], functional score [P = .2457], or range of motion [P = .2514]). The average pain score in knees with lateral patellar contact was higher (48.1) (less pain) when compared with knees without (46.7). Total knee arthroplasties without lateral patellar contact had a 1.61 times odds of experiencing postoperative pain compared with those TKAs with lateral patellar contact (P = .0025).     

Allograft closure of lateral release after revision total knee arthroplasty

Lateral patellar retinacular release (lateral release) is a common technique for resolving patellar tracking issues during total knee arthroplasty. Complications such as hemarthrosis, wound healing complications, patellar fracture, reflex sympathetic dystrophy, and medial subluxation of the patella have been described. This is a case presentation of a 69-year-old woman who developed severe prepatellar bursitis from a sinus tract resulting from a lateral release after total knee arthroplasty. After failing nonoperative modalities, she was treated with an allograft dermal tissue graft (AlloDerm; LifeCell Corp, Branchburg, NJ) over the defect, which has resulted in resolution of symptoms at 2-year follow-up.     

Bilateral patellar component dissociation in a patient with total knee arthroplasties

We present a case of bilateral patellar component dissociation 6 years after bilateral total knee arthroplasty. The patient had undergone arthroscopic lateral releases bilaterally for patellar maltracking. After repetitive trauma, the patient experienced patellar component dissociation, which was treated arthroscopically by removing the patellar components and leaving the patellae unresurfaced. The patient’s symptoms improved substantially. Our case highlights certain features of the etiology as well as the management of patellar component dissociation in the total knee arthroplasty, showing the important role of arthroscopy.     

Patellar component medialization in total knee arthroplasty

Intraoperative correction of patellar maltracking has traditionally involved the use of a lateral retinacular release. Problems, however, related to lateral retinacular release include increased postoperative pain and wound healing complications, compromised patellar blood flow, and longer rehabilitation. The purpose of this study was to assess the effect of patellar medialization in total knee arthroplasty. One hundred forty patients underwent total knee arthroplasty using the same components. Two groups of 70 patients each made up the study. Group 1 included patients whose patellar components were centralized on the patella, and group 2 consisted of patients in whom the patellar component was medialized to reproduce the patient's anatomic high point (ie, sagittal ridge). Lateral retinacular release was required in 45.5% of the patients in group 1 compared with 17% in group 2. The technique of patellar medialization is described.     

Lateral patellofemoral impingement: a cause of treatable pain after TKA

Multiple etiologies may cause anterior knee pain after total knee arthroplasty. While prior studies have addressed component positioning and surgical technique, no series in the literature describes lateral patellofemoral impingement as a source of the pain. Over a 2-year period at our institution, 18 patients with 19 painful total knee arthroplasties were diagnosed with lateral patellofemoral impingement. All underwent revision surgery with either lateral facetectomy or revision of the patellar dome. These patients were followed with Knee Society scores for 1 year. Knee Society scores were significantly improved at 8 weeks, 16 weeks, and 1 year. Lateral patellofemoral impingement should always be considered in the differential diagnosis of the painful total knee arthroplasty. This should be evaluated clinically through direct palpation of the lateral facet, and radiographically with the sunrise view. Lateral facetectomy or patellar revision can be performed with predictably good clinical results.     

One-stage reconstruction of skin defect and patellar tendon rupture after total knee arthroplasty: A new technique

A case is presented herein in which infected total knee arthroplasty associated with a skin defect and patellar tendon rupture was reconstructed with lateral gastrocnemius-Achilles tendon complex after infection was controlled. The results were satisfactory, and the technique proposed herein is highly promising for treating such complicated circumstances after total knee arthroplasty, as not reported previously.     

Influence of patellar subluxation on ligament balancing in total knee arthroplasty through a subvastus approach. An in vivo study

Post-operative joint stability and ligament balance are crucial factors in the longevity of the prosthesis after total knee arthroplasty (TKA). The influence of patellar position on the balance of the knee is controversial. We studied the influence of patellar subluxation on tibiofemoral pressure distribution in vivo, in 32 knees undergoing TKA through a subvastus approach. We used the e-LIBRA Dynamic Knee Balancing System (Synvasive Technology, El Dorado Hills, CA, USA). This is a device that measures the pressures in the medial and lateral compartment independently. After balancing the knee in flexion with the patella in place, we demonstrated a significant rise in pressure in the medial compartment with subluxation of the patella (p < 0.0001). Our findings give a new insight on the role of the patellar position while balancing a total knee arthroplasty. Surgeons should be aware of this effect when choosing their surgical technique for this operative procedure.     

Mobile-Bearing Total Knee Arthroplasty Improves Patellar Tracking and Patellofemoral Contact Stress : In Vivo Measurements in the Same Patients

Controversies exist in clinical study concerning the effect of rotating platform on patellar tracking. The aim of this in vivo study was to compare tibial rotation, patellar tracking, and patellofemoral contact stress in mobile and fixed-bearing platform intraoperatively in the same knee. Sixty-six knees of posterior-stabilized total knee prostheses were evaluated using a computed tomography–guided navigation system. Medial shift and lateral tilt of patella were significantly smaller in mobile knee. Averaged maximum contact stress was significantly smaller in mobile knee than fixed knee. However, tibial rotation during flexion has no significant difference. This study showed that mobile platform total knee arthroplasty significantly improved patellar tracking and decreased patellofemoral contact stress.     

Patellofemoral function after total knee arthroplasty: gender-related differences

The purpose of the study was to evaluate patellofemoral results in 2 comparable groups of 50 patients, men and women, undergoing total knee arthroplasty. The average follow-up was 6 years. The implant was posteriorly stabilized with a dome patellar arthroplasty. The patients were studied using Knee Society knee and functional scores and the Hospital for Special Surgery (HSS) patellar score. Radiologic study included standard and weight-bearing axial views and a computed tomographic scan to assess component rotation. The 2 groups achieved satisfactory and similar knee scores; women had a significantly lower functional and patellar scores. The incidence of lateral patellar tilt, subluxation, and lateral impingement was decreased in weight-bearing axial views compared with non-weight bearing. Medial bony impingement was evident only in weight-bearing views and correlated with pain (P < .05).     

Postoperative clinical outcome between lateral retraction and eversion of patella following simultaneous bilateral total knee arthroplasty

Aims and objectiveAmong the various exposure technique used in total knee arthroplasty (TKA); the midline medial parapatellar knee approach is most commonly performed; which require mobilisation of patella for adequate surgical exposure. In this study, we compare the effect of patellar eversion with lateral retraction in simultaneous bilateral TKA to find out difference in postoperative clinical outcome between the two patellar mobilisation techniques.MethodsWe enrolled 41 patients who underwent bilateral simultaneous TKR (82 knees) from Nov 2016 to Dec 2018. During surgery patellar eversion was done in one knee and lateral retraction was done in other knee selecting them randomly to reduce the bias. During the follow up period achieving unassisted active straight leg raise (SLR), 90 flexion and complications were recorded. Measurement of Oxford knee society score (OKSS), American knee society score (AKSS), Visual Analogue Scale (VAS) score, and quadriceps strength (measured by handheld dynamometer) was done daily up to one week, 1 month, 3 months, 6 months, and 1 year postoperatively.ResultsThe time of achieving active SLR and 901 flexion postoperatively was quicker in the lateral retraction group with a statistically significant difference. VAS pain score at 1 week and 1 month along with quadriceps strength in 1-month had statistically significant favourable outcomes in the lateral retraction group. Throughout the follow up lateral retraction group had better Oxford and American knee score but the difference being statistically insignificant. No significant difference was found on the complication rate.ConclusionIn comparison to lateral retraction, patellar eversion has an adverse effect in early knee functional recovery after TKA; it delays achieving active SLR, 901 flexion and has unfavourable outcome in functional scores, quadriceps strength, and postoperative pain relief. However it has minimal effects on long term functional outcomes.     

Osteonecrosis of the resurfaced patella following bilateral total knee arthroplasty. A case report and review of the literature

A 77-year-old woman with severe varus and flexion deformity of both knee joints, hypertension, and arteriosclerosis underwent bilateral total knee arthroplasty. Six weeks after the operation on the right knee and four months after the operation on the left knee, osteolysis of the patellas was seen on the radiographs. Three years after the operations, the lateral and inferior poles of both patellas were sclerotic and displaced. There was no knee pain and no extension lag throughout the follow-up period. This case suggests that the prognosis of patellar osteonecrosis after total knee arthroplasty is good if the continuity of the retinaculum and the extensor mechanism are preserved, and if instability of the knee does not occur.