Total knee arthroplasty after patellectomy

Patellar reconstruction following previous patellectomy: a review of the literature and a case series using distal femoral autograft during total knee arthroplasty

During total knee arthroplasty, the reconstruction of the patella following a previous patellectomy is challenging, and is undertaken to improve functional outcomes and patient satisfaction. In this case series, we have reconstructed the patella using a femoral condyle resected during total knee arthroplasty. The resected femoral condyle with best available bone stock is selected and secured to the extensor mechanism. We reviewed the preoperative indications and postoperative outcomes of two patients who underwent the above procedure at our Institute, and compared this to the literature. The cases include a 68-year old male (6 months follow-up) who sustained a multi-fragmentary fracture of his right patella and underwent a patellectomy 30 years previously, and a 45-year old female (4 years follow-up) who underwent a left-sided patellectomy 15 years previously following polytrauma. As a result of progressive osteoarthritis they required total knee arthroplasty, and simultaneous patella reconstruction with a femoral condyle autograft. Compared to their preoperative range of motion, both patients demonstrated an improvement post-operatively with successful pain-free knee function, with no radiological signs of graft resorption. In this limited, small series we have reported two patients who are clinically and functionally satisfied by the outcome of surgery, with comparable outcomes to alternative methods. We believe the use of a femoral condyle autograft for patellar reconstruction is a safe and simple technique that optimises knee kinematics, without associated donor morbidity.

Total knee arthroplasty after patellectomy: A meta-analysis of case-control studies

BACKGROUND

Post-patellectomy patients represent a specific subset of patients who can develop painful and disabling knee osteoarthritis that requires Total Knee Arthroplasty (TKA). The aim of this study was to conduct a meta-analysis comparing the outcome of TKA in patients with previous patellectomy to those with an intact patella.

METHODS

A systematic search of electronic databases (PubMed, Medline, Embase, and Cochrane Library) was performed. Data on study setting, type of implant, outcome and associated complications were extracted. Quality assessment was performed using the Newcastle-Ottawa Scale. Random effects meta-analyses were used to combine the results of included studies.

RESULTS

Seven case-control studies were found that met the search criteria. Compared to patients with an intact patella, patients with a previous patellectomy were less likely to have an 'excellent' or 'good' outcome (OR: 0.3, 95% CI: 0.14 to 0.65). The weighted mean post-operative knee flexion arc was 6.58° less in patients with a previous patellectomy (95% CI: -12.79, -0.37). The risk of complication occurring in a patella-deficient knee was higher, with a pooled OR of 1.97 (95% CI=1.10 to 3.51).

CONCLUSIONS

The current evidence that compares the outcome of knee arthroplasty in patients with a previous patellectomy to patients with an intact patella is mostly based on TKAs performed in the 1980s and 1990s. Total knee replacement in patients with an intact patella results in superior outcomes compared to those with a previous patellectomy. In patients with a previous patellectomy, the arc of flexion is slightly less and the complication rate is significantly higher.

Increased Risk of Postoperative Complications After Total Knee Arthroplasty in Patients With Previous Patellectomy

BACKGROUND

Few studies have reported the results of total knee arthroplasty (TKA) in patients with previous patellectomy. The purpose of this study was to assess the risk of complications and survivorship of primary TKA in patients who previously had a patellectomy in comparison to those undergoing TKA with patellar resurfacing.

METHODS

This was a historical cohort study and comprised 134 knees with previous patellectomy in a cohort of 17,946 primary TKA procedures at a single institution between 1985 and 2010. Multivariable Cox regression analyses were used to estimate the risk of complications and revisions in patients with previous patellectomy.

RESULTS

When compared to TKA with patellar resurfacing, the risk of complications (hazards ratio: 1.38, 95% confidence interval: 1.05, 1.81) was significantly higher in post-patellectomy knees, but there was no difference in the risk of revisions (hazards ratio: 1.32, 95% confidence interval: 0.80, 2.18). There was no significant difference between the posterior-stabilized and cruciate-retaining designs in terms of both complications and revisions (P > .05). The most common complications in post-patellectomy knees were instability, delayed healing, and infection.

CONCLUSION

TKA patients with previous patellectomy have a higher risk of complications but not a higher risk of revisions.

Postoperative Knee Flexion Angle Is Affected by Lateral Laxity in Cruciate-Retaining Total Knee Arthroplasty

BACKGROUND

Although many studies have reported that postoperative knee flexion is influenced by preoperative conditions, the factors which affect postoperative knee flexion have not been fully elucidated. We tried to investigate the influence of intraoperative soft tissue balance on postoperative knee flexion angle after cruciate-retaining (CR) total knee arthroplasty (TKA) using a navigation and an offset-type tensor.

METHODS

We retrospectively analyzed 55 patients with osteoarthritis who underwent TKA using e.motion-CR (B. Braun Aesculap, Germany) whose knee flexion angle could be measured at 2 years after operation. The exclusion criteria included valgus deformity, severe bony defect, infection, and bilateral TKA. Intraoperative varus ligament balance and joint component gap were measured with the navigation (Orthopilot 4.2; B. Braun Aesculap) while applying 40-lb joint distraction force at 0° to 120° of knee flexion using an offset-type tensor. Correlations between the soft tissue parameters and postoperative knee flexion angle were analyzed using simple linear regression models.

RESULTS

Varus ligament balance at 90° of flexion (R = 0.56; P < .001) and lateral compartment gap at 90° of flexion (R = 0.51; P < .001) were positively correlated with postoperative knee flexion angle. In addition, as with past studies, joint component gap at 90° of flexion (R = 0.30; P < .05) and preoperative knee flexion angle (R = 0.63; P < .001) were correlated with postoperative knee flexion angle.

CONCLUSION

Lateral laxity as well as joint component gap at 90° of flexion is one of the most important factors affecting postoperative knee flexion angle in CR-TKA.

Total knee arthroplasty in a patient with an ankylosing knee after previous patellectomy

Patellectomized patients may have less satisfactory clinical outcomes following total knee arthroplasty (TKA) due to a decreased extensor mechanism efficiency and potential instability. Furthermore, the existing literature does not provide concrete guidance on the expected results of TKA or the type of implant that should be used in patellectomized patients. We present a case of a patient with an ankylosing knee who had undergone patellectomy due to gunshot injury 45 years ago and was treated with primary TKA using a posterior stabilized prosthesis at our institution. TKA using this prosthesis in the ankylosed knee with a previous history of patellectomy yielded good results in terms of postoperative clinical scores, range of motion and joint stability.

Partial lateral facetectomy plus Insall's procedure for the treatment of isolated patellofemoral osteoarthritis: survival analysis

PURPOSE

The purpose of this study was to report the survival analysis of partial lateral facetectomy and Insall's procedure in patients with isolated patellofemoral osteoarthritis, and to assess the risk and protective factors for failure of this procedure.

METHODS

From 1992 to 2004, all subjects with isolated patellofemoral osteoarthritis who met the inclusion criteria and underwent this procedure were enrolled. Risk and protective factors for failure (failure considered as the need for total knee arthroplasty) were assessed by comparing obtained baseline data between failed and non-failed cases. Eighty-seven cases (mean (SD) age 61.8 (7.7) years, mean (SD) follow-up 9.6 (3.2) years) were included.

RESULTS

Twenty-three failed cases were found. Mean (SD) survival time was 13.6 (0.5) years. At 13 years (last failure case), the cumulative survival was 59.3 %. Baseline medial tibiofemoral pain, genu flexum, and worst grade of tibiofemoral osteoarthritis were significant risk factors for failure (p < 0.0001, p = 0.02, p < 0.0001, respectively). In contrast, higher anatomical (p = 0.02) and total (p = 0.03) knee society score (KSS) scores, absence of knee effusion (p = 0.03), higher value of the Caton-Deschamps index (p = 0.03), and lateral position of the patella (p = 0.01) were all protective factors against failure.

CONCLUSION

The treatment for isolated patellofemoral osteoarthritis through partial lateral facetectomy and Insall's procedure demonstrated good long-term survival. The presence of preoperative medial tibiofemoral pain, genu flexum, and incipient tibiofemoral osteoarthritis increased the risk of failure of this procedure. In contrast, higher anatomical and total KSS scores, absence of knee effusion, higher value of the Caton-Deschamps index, and lateral position of the patella were found to protect against failure.

Significant effect of the posterior tibial slope and medial/lateral ligament balance on knee flexion in total knee arthroplasty

PURPOSE

The intra-operative femorotibial joint gap and ligament balance, the predictors affecting these gaps and their balances, as well as the postoperative knee flexion, were examined. These factors were assessed radiographically after a posterior cruciate-retaining total knee arthroplasty (TKA). The posterior condylar offset and posterior tibial slope have been reported as the most important intra-operative factors affecting cruciate-retaining-type TKAs. The joint gap and balance have not been investigated in assessments of the posterior condylar offset and the posterior tibial slope.

METHODS

The femorotibial gap and medial/lateral ligament balance were measured with an offset-type tensor. The femorotibial gaps were measured at 0°, 45°, 90° and 135° of knee flexion, and various gap changes were calculated at 0°-90° and 0°-135°. Cruciate-retaining-type arthroplasties were performed in 98 knees with varus osteoarthritis.

RESULTS

The 0°-90° femorotibial gap change was strongly affected by the posterior condylar offset value (postoperative posterior condylar offset subtracted by the preoperative posterior condylar offset). The 0°-135° femorotibial gap change was significantly correlated with the posterior tibial slope and the 135° medial/lateral ligament balance. The postoperative flexion angle was positively correlated with the preoperative flexion angle, γ angle and the posterior tibial slope. Multiple-regression analysis demonstrated that the preoperative flexion angle, γ angle, posterior tibial slope and 90° medial/lateral ligament balance were significant independent factors for the postoperative knee flexion angle. The flexion angle change (postoperative flexion angle subtracted by the preoperative flexion angle) was also strongly correlated with the preoperative flexion angle, posterior tibial slope and 90° medial/lateral ligament balance.

CONCLUSION

The postoperative flexion angle is affected by multiple factors, especially in cruciate-retaining-type TKAs. However, it is important to pay attention not only to the posterior tibial slope, but also to the flexion medial/lateral ligament balance during surgery. A cruciate-retaining-type TKA has the potential to achieve both stability and a wide range of motion and to improve the patients' activities of daily living.

Influence of intra-operative parameters on postoperative early recovery of active knee flexion in posterior-stabilized total knee arthroplasty

PURPOSE

Active knee flexion is more important for daily activities than passive knee flexion. The hypothesis is that the intra-operative parameters such as osteotomized bone thickness and soft tissue balance affect the postoperative active flexion angle in total knee arthroplasty (TKA). Therefore, we evaluate the influence of intra-operative parameters on postoperative early recovery of active flexion after posterior-stabilized (PS) TKA.

METHODS

The subjects were 45 osteoarthritic knees undergoing primary PS TKA with anterior-reference technique. Intra-operative soft tissue balance was measured using an offset type tensor, and each osteotomized bone thickness was also measured. Pre- and postoperative active knee flexion angles were measured using lateral radiographs. Liner regression analysis was used to determine the influence of these intra-operative parameters on postoperative active flexion angles or recovery of active flexion angles.

RESULTS

Pre-operative flexion angle was positively correlated with postoperative flexion angle (R = 0.52, P = 0.0002). Postoperative flexion angle was negatively correlated with the osteotomized bone thickness of femoral medial posterior condyle (R = -0.37, P = 0.012), and femoral lateral posterior condyle (R = -0.36, P = 0.015). Recovery of flexion angle was slightly negatively correlated with gap difference calculated by subtracting joint gap at extension from that at flexion between osteotomized surfaces (R = -0.30, P = 0.046).

CONCLUSIONS

The osteotomized bone thickness of the femoral posterior condyle is a significant independent factor of postoperative flexion angles. This indicates that the restoration of the posterior condyle offset may lead to larger postoperative active flexion angles in PS TKA.

Midterm results of cruciate retaining total knee arthroplasty in patellectomized patients

BACKGROUND

Total knee arthroplasty (TKA) in patellectomized patients gives inferior results when compared with those in which the patella is present. The literature is ambiguous about the role of cruciate retaining or sacrificing implants for these knees. In this study, we assessed the midterm results of TKA in patellectomized knees using a cruciate retaining implant.

MATERIALS AND METHODS

Thirty three patients with a prior patellectomy underwent a cruciate retaining TKA and were followed up for an average of 9.3 years (range 2-14 years). At each followup visit, they were evaluated clinically, radiologically and by the Hospital for Special Surgery Scoring System.

RESULTS

Twenty one knees did not have any pain or difficulty in climbing stairs, 10 knees were slightly painful on stairs but pain free on walking on flat ground and two knees experienced mild to moderate pain on walking up and down stairs as well as on flat ground. The average range of motion preoperatively was 87°, which postoperatively increased to 118°. The average Hospital for Special Surgery Knee scores increased from 52 to 89 points. None of the knees showed any progressive radiolucencies or evidence of any loosening/osteolysis or fractures in followup.

CONCLUSION

Cruciate retaining TKA offers good results at midterm followup in patients with a prior patellectomy.

Patellofemoral osteoarthritis treated by partial lateral facetectomy: results at long-term follow up

Excision of the eroded lateral patellar facet has been suggested as an acceptable treatment for short-term pain reduction in patients with isolated patellofemoral osteoarthritis. The outcome of this procedure at long-term is however not known. We therefore reviewed the results of 155 consecutive patients (168 knees) treated at our institution with lateral facetectomy at an average follow up of 10.9 years (± 6.9 years SD). During follow up 62 knees (36.9%) had failed and were revised to either TKA (60 knees), patellofemoral arthroplasty (one case) or total patellectomy (one case). Average time to reoperation in the failure group was 8.0 years (± 6.2 years SD). Kaplan-Meier survival rates with reoperation as endpoint were 85% at 5 years, 67.2% at 10 years, and 46.7% at 20 years respectively. At final follow up 79 (74.5%) of the knees that had not been re-operated were rated as either good or fair, which corresponds to 47% of the original group. Our study therefore demonstrates that a satisfactory outcome after lateral patellar facetectomy for isolated patellofemoral osteoarthritis can be expected in approximately half of the cases at 10 year follow up.

Reconstruction of the patella with an autogenous iliac graft: clinical and radiologic results in thirteen patients

PURPOSE

Extension lag, quadriceps weakness and subluxation of the extensor apparatus are known complications of patellectomy. In the case of total knee joint replacement with a nonconstrained system an instability may be encountered. Reconstruction of the patella allows restoration of the moment arm to improve quadriceps leverage. The goal of our study was to analyse the clinical and radiological results after reconstruction of the patella with an autogenous iliac graft.

METHODS

13 previously patellectomized patients had reconstruction of the patella with an autogenous iliac graft and were retrospectively studied by clinical and radiographic examination. For evaluation we used the scores of Feller and the Knee Society. Also, all complications were recorded.

RESULTS

After an average follow-up of 40.1 months, nine patients had full strength of the quadriceps, while six had an improved function of the extensor apparatus. The mean Feller score was 21.8 and the Knee Society score was 67.3 for knee and 57.5 for function. Six complications occurred including three infections, two problems with the replaced patella and one fracture of the anterior superior iliac spine.

CONCLUSIONS

Reconstruction of the patella with an autogenous iliac graft enables the strength of the extensor apparatus with restoration of the knee joint.

Influence of intra-operative joint gaps on post-operative flexion angle in posterior cruciate-retaining total knee arthroplasty

PURPOSE

The purpose of this study is to examine the joint component gap and its relationship with post-operative flexion angles in posterior cruciate-retaining (CR) total knee arthroplasty (TKA). In posterior-stabilized (PS) TKA, an inverse correlation between the joint component gap and the post-operative flexion angle was reported. However, the kinematics of the joint component gap has a different pattern in PS and CR TKA. It was hypothesised that CR TKA has a different correlation between the joint component gap and the post-operative flexion angle compared to PS TKA.

METHODS

The joint component gap was measured with an offset-type tensor. The joint component gaps were measured at 0°, 10°, 30°, 60°, 90° and 120° knee flexion angle and various values of the change in the joint component gap were calculated; 10°-0°, 30°-0°, 60°-0°, 90°-0° and 120°-0°. Multivariate regression analysis was used to determine the influencing of these parameters to post-operative knee flexion angle.

RESULTS

The post-operative flexion angle was positively correlated with a joint component gap of 90° and 120° and the values of the change in the joint component gap of 90°-0° and 120°-0°. Multivariate regression analysis demonstrated pre-operative knee flexion angle, and the values of the change in the joint component gap of 90°-0° had a significant independent factor of post-operative knee flexion angle.

CONCLUSIONS

Post-operative flexion angle is multi-factorial. However, it is important to avoid flexion component gap tightness as well as excessive flexion component gap looseness for acquisition of better flexion angle in CR TKA.

LEVEL OF EVIDENCE

IV.

Porous tantalum patellar components in revision total knee arthroplasty minimum 5-year follow-up

Revision total knee arthroplasty can be complicated by severe patellar bone loss, precluding the use of standard cemented patellar components. This study evaluated the midterm outcomes of porous tantalum (PT) patellar components. Twenty-three PT components were used in 6 men and 17 women (average age, 62 years). All patellae had less than 10-mm residual thickness. The PT shell was secured to host bone, and a 3-peg polyethylene component was cemented onto the shell. In 2 patients, the PT component was sutured directly to extensor mechanism. Average follow-up was 7.7 years (range, 5-10 years). At follow-up, the Knee Society scores for pain and function averaged 82.7 and 33.3, respectively, whereas the mean Oxford knee score was 32.6. Four patients underwent revision surgery. Survivorship was 19 (83%) of 23 patients. Porous tantalum patellar components can provide fixation where severe bone loss precludes the use of traditional implants. Failures were associated with avascular residual bone and fixation of components to the extensor mechanism.

The patellar thinning osteotomy in patellofemoral arthritis: four to 18 years' follow-up

Isolated patellofemoral osteoarthritis can be a disabling disease. When conservative treatment fails, surgical options can be unpredictable and may be considered too aggressive for middle-aged and active people. We analysed the clinical and radiological results of a new coronal osteotomy involving thinning of the patella in a selected group of patients with isolated patellofemoral osteoarthritis. Since 1991, 31 patients (35 knees) have been treated, of whom 34 were available for follow-up at a mean of 9.1 years. The Knee Society Score, the Patellar score and the Short-form-36 questionnaire were used for clinical evaluation. We also examined the radiological features to confirm bone consolidation and assess the progression of osteoarthritis. A significant improvement in the functional scores and radiological parameters was noted. All patients except one were satisfied with the operation. Radiological progression of the patellofemoral osteoarthritis was slowed but radiological femorotibial osteoarthritis progressed in 23 (65%) cases, with a total knee replacement becoming necessary in four cases without technical problems in resurfacing the patella. We compared the results with other forms of surgical treatment reported in the literature. This treatment offers good clinical and radiological results, presenting an alternative method of managing patellofemoral osteoarthritis.

Techniques for managing anatomic variations in primary total knee arthroplasty

Primary total knee arthroplasties have high success rates, but certain patient anatomic or other variations may adversely affect the performance or the clinical outcomes of these procedures. Various technologies and techniques have been developed in attempts to overcome these challenges. However, there is controversy concerning whether these innovations are beneficial. This article assessed the scientific evidence regarding the use of these technologies to address various anatomic variations by examining the complete body of literature. The anatomic variations that were examined included extra-articular deformities, bone deficiencies, ligamentous instability, post-patellectomy knees, patella baja, variations in bone size and high-flexion knees. Recommendations for each circumstance were presented based upon the available scientific evidence.

Patellar reconstruction using distal femoral autograft in a patellectomized patient undergoing total knee arthroplasty

Patellectomized patients have less satisfactory clinical outcomes after total knee arthroplasty because of a decreased extensor mechanism efficiency and potential instability attributable to loss of anterior restraint. We report a patient, with a prior history of patellectomy, who underwent simultaneous patellar reconstruction using distal femoral autograft during the total knee arthroplasty. The patient has been followed up for 24 months with excellent postoperative knee scores with radiographically established graft viability.

Influence of intra-operative joint gap on post-operative flexion angle in osteoarthritis patients undergoing posterior-stabilized total knee arthroplasty

Recently, we developed a new tensor for total knee arthroplasty (TKA) procedures enabling soft tissue balance assessment throughout the range of motion while reproducing post-operative joint alignment with the patello-femoral (PF) joint reduced and the tibiofemoral joint aligned. Using the tensor with a computer-assisted navigation system, we investigated the relationship between various intra-operative joint gap values and their post-operative flexion angles. An increased value during the extension to flexion gap and a decreased value during the flexion to deep flexion gap with PF joint reduced, not everted, showed an inverse correlation with post-operative knee flexion angle, not pre-operative flexion angle. In conclusion, understanding the characteristics of joint gap kinematics in posterior-stabilized TKA under physiological and reproducible joint conditions may enable the prediction of the post-operative flexion angle and help to determine the appropriate intra-operative joint gap.

Whole patellar allograft for total knee arthroplasty after previous patellectomy

We treated seven consecutive patients (nine knees) with previous total knee arthroplasties and patellectomies with whole patellar allograft reconstructions of the extensor mechanism. The patients' extensor mechanism soft tissue sleeve was intact, but the patella was not present. Deficient patellae were reconstructed using patellar ligament (whole patella) quadriceps tendon allograft. Six knees had previous patellectomies and underwent primary total knee arthroplasties. Three knees had previous patellectomies and underwent revision total knee arthroplasties. Two patients who had primary total knee arthroplasties had failed results; one from infection and one from aseptic allograft resorption and fragmentation. One patient in the revision total knee arthroplasty group had failed results from infection. After an average followup of 44 months (range, 39-48 months), the six intact knees had an increase in quadriceps strength of one grade. The average Knee Society knee and function scores increased from 59 and 63 points, respectively, to 85 and 67 points, respectfully. The average patellar thickness was 24 mm 6 weeks postoperatively, and 15 mm (38% decrease) at the most recent followup. Patellar allografting improved quadriceps function by restoring patellar height. However, a high risk of allograft complications can occur with this procedure.

LEVEL OF EVIDENCE

Therapeutic study, Level IV (case series).

Patellectomy after total knee arthroplasty

We retrospectively reviewed nine patients who had condylar TKA and subsequently had a patellectomy between 1969 and 2003. One patient was lost to followup, but the remaining eight patients were followed up for an average of 49 months after patellectomy. All patellectomies were done after comminuted patellar fractures at an average of 21 months (range, 4-88 months) after the initial arthroplasty. Knee scores after the initial arthroplasty were 83 points (range, 69-97 points) and 49 points (range, 10-100 points) for pain and function, respectively. Knee scores after patellectomy were 81 (range, 20-97) and 28 (range, 0-80) for pain and function, respectively. The average range of motion before and after patellectomy was 0 degrees to 104 degrees and 2 degrees to 106 degrees , respectively. Four patients had mild extensor lags at final examination, but all were less than 10 degrees . Two patients were unable to use stairs. Two patients had complications consisting of quadriceps tendon rupture and secondary instability. Midterm results after patellectomy show knee scores for pain that are comparable to those after initial arthroplasties, but the function scores were not as good. Fifty percent of the patients had extensor lags but all were mild (< 10 degrees ). Patellectomy can provide pain relief after a patellar fracture after total knee arthroplasty but the functional results are frequently poor.

LEVEL OF EVIDENCE

Therapeutic study, Level IV-1 (case series). See the Guidelines for Authors for a complete description of levels of evidence.

Influence of hip position on knee flexion angle in patients undergoing total knee arthroplasty

The influence of hip position on knee flexion angle before total knee arthroplasty (TKA) and that after TKA were investigated and compared. Sixty-six patients (70 knees) with osteoarthritis who were undergoing TKA were examined using lateral radiographs of maximum knee flexion angle with the hip joint at 0 degrees extension and 90 degrees flexion. The postoperative rate of decrease in knee flexion angle caused by hip extension was significantly larger compared with the value before surgery. The preoperative rate of decrease in knee flexion angle caused by hip extension showed strong inverse correlation with the preoperative and postoperative knee flexion angle ratio. In conclusion, tightness of the extensor mechanism is present in all knees undergoing TKA and especially has a strong influence on the postoperative flexion angle of the knee.

Total knee arthroplasty in a patellectomised posterior cruciate ligament-deficient knee: a new technique of patellar tendon bone grafting

Total knee arthroplasty in patients with previous patellectomy are less successful because of anteroposterior instability, residual pain and the loss of the mechanical advantage of the patella. To restore the moment arm of the quadriceps, the senior author (C.W.) described the technique of bone grafting the patellar tendon in a patient using the tibial plateau obtained from the routine tibial cut during total knee arthroplasty. The tibial eminence was used as the interfacetal ridge of the 'created' patella. At follow-up, the results were excellent with a postoperative knee society score of 90 and a postoperative patient functional score of 92. Radiological investigations showed a well-incorporated graft in the patellar tendon.

Advanced osteoarthritic knee with neglected patellar tendon rupture treated with total patellectomy and total knee arthroplasty

Loss of the knee extensor mechanism results in a change of normal knee joint alignment and functional anteroposterior instability. In patients with neglected or chronic patellar tendon rupture, advanced degenerative change of the knee joints may develop at the later stage. We present a case of a 64-year-old man with chronic left patellar tendon rupture and 10-cm proximal patella migration associated with advanced osteoarthritis of the knee. Total patellectomy and simultaneous total knee arthroplasty (TKA) relieved his symptoms and disability successfully. His left knee still did well at 7-year follow-up.

Use of a trabecular metal patella for marked patella bone loss during revision total knee arthroplasty

This study evaluates the short-term results following patellar resurfacing with a trabecular metal patella shell in the setting of marked patellar bone loss at the time of revision total knee arthroplasty (TKA). Twenty consecutive patients undergoing revision TKA with the use of a trabecular metal patella were evaluated at a mean 23-month follow-up. All patients had marked patellar bone loss at surgery precluding resurfacing with a standard cemented patellar button. Results were good or excellent in 17 of 20 patients. There were no displacements of any trabecular metal patella shells, and the fixation appeared excellent despite the poor quality of bone remaining. Complications included 3 patients with polar patella fractures postoperatively. Qualitatively, these results compare favorably with patellar resection arthroplasty in this setting.