Unconstrained knee arthroplasty after patellectomy

Prior Patellectomy: A Systematic Review and Meta-Analysis Comparing Cruciate-Retaining and Posterior-Stabilized Total Knee Arthroplasty Survivorship and Reported Outcomes

BACKGROUND

In the setting of total knee arthroplasty (TKA), prior patellectomy historically prompted the use of increased constraint implants, specifically posterior-stabilized (PS) designs. However, modern case series have reported similar outcomes utilizing cruciate-retaining (CR) implants. The primary outcome of this study was to compare implant retention rates between these 2 implant designs in prior patellectomy patients. Secondary outcomes included a comparison of patient-reported outcome scores and cause for revision.

METHODS

A comprehensive systematic review was performed using Web of Science, PubMed, and Scopus databases per the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Boolean operator search terms included "patellectomy AND (arthroplasty) OR (replacement)." Case reports, review articles, < 2 years of follow-up, and studies in which the implant design could not be ascertained were excluded. An initial screening of titles and abstracts for inclusion was performed, followed by a full manuscript review of eligible articles. Single-data extraction was performed, followed by subsequent statistical analysis.

RESULTS

A total of 9 studies (209 knees) met the inclusion criteria. The average time from patellectomy to TKA was 16.1 years. While all patients had significant improvement in functional outcomes, CR implants displayed proportionally greater improvement in Knee Society Scores compared to PS implants (+108 versus +98%, P ≤ .001). However, there was a significantly greater rate of revision in the CR cohort compared to PS (18.6 versus 2.6%, P = .002).

CONCLUSIONS

Prior patellectomy patients undergoing TKA have significant improvements in patient-reported functional outcomes and high midterm retention rates. While CR implant designs portend a potentially greater improvement in functional outcomes, they also have a greater risk for revision than their PS implant counterparts. However, contemporary implant designs and operative techniques likely render revision rates equivocal between CR and PS implants in postpatellectomy patients.

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.

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.

Does patellectomy jeopardize function after TKA?

BACKGROUND

The patella provides important mechanical leverage to the knee extensor mechanism. Patellectomy does not exclude the development of tibiofemoral arthrosis.

QUESTIONS/PURPOSES

We asked whether (1) TKA provides improvements in clinical outcome scores in patellectomized knees and (2) the scores of TKA in patellectomized knees are comparable to those in knees with intact patellae.

METHODS

We evaluated 50 patients (52 primary TKAs) with patellectomized knees and a control group of 52 patients (52 primary TKAs) with intact patellae matched for age, sex, implant, and surgical year between 1984 and 2009. We compared the preoperative and latest postoperative SF-12, WOMAC, and Knee Society score (KSS). Minimum followup was 24 months (mean, 69 months; range, 24-204 months).

RESULTS

The mean WOMAC score in the control group improved from 41.8 (range, 7.5-72.4) preoperatively to 69.1 (range, 17.0-100.0) postoperatively, while that in the patellectomized group improved from 35.8 (range, 5.2-62.2) to 61.3 (range, 17.5-96.2). The mean KSS improved from 80.4 (range, 4.0-143.0) preoperatively to 161.4 (range, 69.0-200.0) postoperatively in the control group and from 76.9 (range, 5-134) to 136.8 (range, 7-199) in the patellectomized group. Mean postoperative WOMAC scores were comparable between the two groups, while the mean KSS was lower in the patellectomized group. The mean SF-12 scores were not different after TKA or between groups.

CONCLUSIONS

Despite the mechanical disadvantage to the knee extensor mechanism rendered by a previous patellectomy, TKA for tibiofemoral arthrosis in these patients relieved pain and restored function, but function was on average lower than that in patients with intact patellae.

LEVEL OF EVIDENCE

Level III, therapeutic study. See Instructions for Authors for a complete description of levels of evidence.

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.

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.

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.

Patellar component resection in revision and reimplantation total knee arthroplasty

Between 1979 and 1995, 34 knees in 31 patients had a revision or reimplantation total knee arthroplasty in which the patellar component could not be reinserted. The patellar bone stock in each of those cases was compromised markedly and precluded adequate prosthetic fixation. The mean followup after the revision operation was 3.5 years (range, 2-14 years). The Knee Society knee score improved from a mean of 59 points preoperatively to a mean of 75 points postoperatively. The function score improved from a mean of 46 points preoperatively to a mean of 69 points postoperatively. Complications occurred in five patients: one patient sustained a patellar fracture that required no additional treatment; one experienced intermittent episodes of patellar subluxation; one had a recurvatum deformity develop and was treated with a brace; one had persistent knee stiffness and had four manipulations; and one patient had an extensor lag of 30 degrees develop. Twenty-six patients were satisfied with the results of their revision operations and five were dissatisfied. Ten patients had persistent knee symptoms referable to the patellofemoral articulation: mild pain in three; moderate pain in six; and severe pain in one. This study suggests that resection of the patellar component during revision or reimplantation total knee arthroplasty may be a reasonable approach for patients with markedly compromised patellar bone stock; however, mild or moderate anterior knee pain can be expected to persist in as much as 1/3 of these patients.

Total knee arthroplasty after a previous patellectomy

We performed a retrospective, matched-control analysis of the results of total knee arthroplasty with cement in twenty-two patients who had had a previous patellectomy for either a fracture of the patella (sixteen patients) or severe patellofemoral osteoarthrosis or chondromalacia patellae (six patients). Nine of the patients were men and thirteen were women. The average age at the time of the total knee arthroplasty was sixty-nine years (range, fifty-nine to seventy-four years). The average time from the patellectomy to the total knee arthroplasty was eight years (range, two to fourteen years). The patients were divided into two groups according to the type of implant that had been used. Group A (nine patients) had had insertion of a posterior stabilized prosthesis (a posterior cruciate-sacrificing implant) and Group B (thirteen patients) had had insertion of a posterior cruciate-sparing implant. Two computer-generated matched groups of patients who had had a total knee arthroplasty with insertion of implants that were identical to those in the study groups but who had not had a previous patellectomy served as controls. Group C consisted of patients who had had insertion of the same type of implant as that used in Group A, and Group D consisted of patients who had had insertion of the same type of implant as that used in Group B. All patients were evaluated before the arthroplasty and five years postoperatively with use of the rating system of the Knee Society.(ABSTRACT TRUNCATED AT 250 WORDS)

Primary total knee arthroplasty after patellectomy

The results of twenty-two consecutive primary total knee replacements, performed an average of nine years (range, one to twenty-three years) after a patellectomy in twenty-two patients, were reviewed retrospectively. The average duration of follow-up was seven years (range, three to fifteen years). The average age of the patients at the time of the arthroplasty was sixty-seven years (range, thirty-six to eighty-nine years). The average Hospital for Special Surgery knee score was 46 points (range, 22 to 74 points) preoperatively and 76 points (range, 45 to 97 points) postoperatively. Thirteen patients had an excellent or good result and seven had a fair or poor result; in two patients, the operation was considered a failure. Except for one patient who had myasthenia gravis, all patients could climb stairs in reciprocal manner. Four patients lacked 5 to 20 degrees of active extension compared with passive extension. With respect to the over-all results, there was no significant difference among the four types of prostheses that were used (p = 0.2). The patients who had received an Insall-Burstein posterior stabilized prosthesis had better scores for pain and function than did the patients who had received a total condylar I prosthesis (p = 0.005 and 0.01, respectively). There was a direct correlation between the knee score and the number of years that had elapsed since the patellectomy. The longer the interval between the patellectomy and the total knee replacement, the higher the postoperative knee score (r = 0.78, p < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)