Kelly G. Vince

The Total Condylar Knee Prosthesis

Few topics in the orthopaedic literature have become more boring or contentious than the recitation of good surgical results, especially when a prosthetic device is involved. Nonetheless, these devices and the operations devised for them must be assessed. This type of clinical research should identify the principles of the design and surgical technique to determine whether they should be abandoned, retained or enhanced.

Internal rotation of the tibial component is frequent in stiff total knee arthroplasty.

BackgroundStiffness complicating TKA is a complex and multifactorial problem. We suspected internally rotated components compromised motion because of pain, patellar maltracking, a tight medial flexion gap, and limited femoral rollback on a conforming lateral tibial condyle.Questions/purposesWe sought to determine: (1) the incidence of internal rotation of the femoral and tibial components in stiff TKAs; (2) if revision surgery that included correction of rotational positioning improved pain, ROM, and patellar tracking; and (3) if revision altered nonrotational radiographic parameters.MethodsFrom a cohort of 52 patients with TKAs revised for stiffness, we performed CT scans of 34 before and 18 after revision to quantify rotational positioning of the femoral and tibial components using a previously validated scanning protocol.ResultsAll 34 patients with TKAs had internal rotation of the summed values for tibial and femoral components (mean, 14.8°; range, 2.7°–33.7°) before revision for stiffness. The incidence of internal rotation was 24 of 34 femoral (mean, 3.1°; internal) and 33 of 34 tibial components (mean, 13.7° internal). Revision arthroplasty improved Knee Society function, knee, and pain scores. Mean extension improved from a contracture of 10.1° to 0.8° and flexion from 71.5° to 100°. Postrevision CT scans confirmed correction of component rotation. Nonrotational parameters were unchanged.ConclusionsWe recommend CT scanning of patients with stiff TKAs before surgical intervention to identify the presence of internally rotated components.Level of EvidenceLevel IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Continuous passive motion after total knee arthroplasty

Sixty-two patients undergoing primary total knee arthroplasty were studied prospectively. There were 42 patients in whom continuous passive motion (CPM) was used after surgery and 20 controls. The two groups were comparable with respect to age, diagnosis, sex, weight, and preoperative deformity and motion. The mean length of time required for CPM patients to achieve 90 degrees of flexion (9.1 days) was shorter than that for the control group (13.8 days). At the time of discharge from the hospital, however, there was no significant difference between the groups in amount of either flexion or extension. All patients had venograms performed after arthroplasty; the incidence of positive studies indicating thrombophlebitis was 45% in CPM patients and 75% in controls. These data demonstrate that CPM after knee arthroplasty enables patients to recover motion more quickly and affords some protection against deep vein thrombosis.

Ten- to 12-year followup of the Insall-Burstein I total knee prosthesis.

The Insall-Burstein Posterior Stabilized knee prosthesis (Insall-Burstein I), developed at The Hospital for Special Surgery in 1978, has a metal-backed nonmodular tibial component. The polyethylene articular surface was directly molded. The purpose of the current study was to evaluate long-term wear with this design. The first 100 total knee arthroplasties (86 patients) performed by the senior author were followed prospectively. The average age of the patients at the time of surgery was 69.7 years (range, 45–89 years). The primary diagnoses were osteoarthritis in 77 knees (66 patients), inflammatory arthritis in 17 knees (14 patients), and posttraumatic arthritis in the remaining six knees (six patients). Thirty-eight knees (35 patients) had varus angulation, 14 knees (13 patients) had valgus angulation, and 48 knees (40 patients) had a 0 °to 10 °tibiofemoral angle preoperatively. All patients were evaluated at 10 to 12 years followup. Knee Society scores and radiographs were obtained. Thirty-six knees were in 30 patients who had died and two knees were in two patients who were infirm. Telephone evaluation only was available for eight knees (seven patients), leaving 54 knees (47 patients) for direct clinical and radiographic evaluation. No patients were lost to followup. The average Knee Society clinical score at latest followup was 91.6 points. The average function score was 69 points. One knee arthroplasty failed because of tibial loosening, one failed because of patella wear and fracture, two failed because of sepsis, and two failed because of nonspecific pain. There were seven patella fractures (7%) in the 100 knees. One of the fractures resulted in a total knee revision (noted above), two resulted in patellar component revision, and another resulted in patellar component removal. The remaining three patella fractures were discovered incidentally and were asymptomatic. There were no patellar dislocations. At long-term radiographic analysis, valgus alignment averaged 6 °(range, 0 °–11 °). Polyethylene wear averaged 0.40 mm. There was no catastrophic wear of tibial polyethylene. Thirty-two knees in 32 patients (65%) had radiolucencies in at least one zone; no lucency filled a zone, and none was wider than 2 mm. The absence of clinically significant tibial polyethylene wear at long-term followup is of particular interest. The performance of the molded, nonmodular polyethylene articulation is encouraging and needs to be analyzed critically against the more widely used machined, modular components used today.

Long-term Outcome of Total Knee Replacement: Does Obesity Matter?

Background: Although arthritic complications are common in the obese, many surgeons are reluctant to perform joint replacements in this population. We compared outcomes of total knee arthroplasties (TKAs) in normal weight and obese patients. Methods: 30 TKAs in 21 obese patients with BMI 30-49 (Group A – mainly mildly and moderately obese) were compared to a matched group of 53 TKAs in 41 non-obese patients with BMI 16-29.9 (Group B). Outcome measures included the Knee Society Score (a composite of clinical and functional parameters), radiographic results, and the need for revision or reoperation. Results: Median follow-up was 11.3 years; no patients were lost to follow-up during this time. The Knee Society Score rose 92 points in Group A to a final score of 184, and 95 points in Group B to a score of 193. There was no statistical difference in Groups A and B between the improvement in scores or the final score achieved. Osteolysis rates were not significantly different between the 2 groups (5% vs 13%), nor were radiolucency rates (0% vs 9.7%). Median alignment was also similar in both groups (8.1° vs 8.0° valgus). 13.3% of Group A required reoperation while none required revision, and 13.2% of Group B required reoperation with 3.8% requiring revision. Survival rates were similar in both groups (71.4% vs 61.5%). Conclusions: Moderate obesity does not affect the clinical and radiologic outcome of TKA. However, TKA results in improved mobility, enhancing the success of subsequent weight loss therapy.

Breakage of a Total Condylar III Knee Prosthesis A Case Report

The authors report the failure of a Total Condylar III (Cintor, Johnson and Johnson, Raynham, MA) knee arthroplasty, implanted in a second revision knee surgery, due to fracture of the tibial spine. The tibial component was in varus position and externally rotated relative to the tibia. This imparted torque and resulted in a spiral fracture of the polyethylene spine. This is the first report of failure of a Total Condylar III prosthesis by mechanical breakage.

Fifteen-Year to 19-Year Follow-Up of the Insall-Burstein-1 Total Knee Arthroplasty

This represents a 15-year to 19-year follow-up of 100 Insall-Burstein-I posterior-stabilized knee prostheses implanted in 86 patients from 1986 to 1989 and originally reported at 10 to 12 years (Thadani et al, 2000). In the original cohort, 6 failures occurred by 10 years. At 15 to 19 years, 55 patients (66 knees) had died; 18 patients were followed with clinical examination and radiographs, and 11 by telephone; 3 knees in 2 patients were lost. There were no new failures or additional surgeries from 10 to 19 years. Three knees exhibited osteolytic lesions. No case required revision due to symptomatic osteolysis or polyethylene wear. Using revision as end point, survival was 92.4% at 19 years. In summary, the prosthesis is likely to outlive the patients when classic indications for age and activity are respected.

Late infection of a total knee arthroplasty with Streptococcus bovis in association with carcinoma of the large intestine.

Infection of a total knee arthroplasty with Streptococcus bovis in a 76-year-old man that led to the diagnosis of a bowel carcinoma is reported. Investigation revealed a malignancy in the ascending colon with extension into the adrenal gland. S bovis in conjunction with colonic neoplasia has been reported in several orthopedic conditions: vertebral osteomyelitis, discitis, lateral neck abscess, and osteomyelitis of the ileum. The relationship of S bovis to endocarditis, meningitis, brain abscesses, and peritonitis has also been well described. However, S bovis is a rare pathogen infecting joint prostheses and should raise the possibility of a gastrointestinal lesion.

Component Alignment in Revision Total Knee Arthroplasty Using Diaphyseal Engaging Modular Offset Press-Fit Stems

We performed a retrospective study of the radiographic position of femoral and tibial components in a series of revision total knee arthroplasties using diaphyseal-engaging, press fit, modular stems. Fifty-two consecutive revision cases were performed. Femoral and tibial component alignment was measured preoperatively and postoperatively. The canal-filling ratio was measured and correlated with anatomic alignment. There was a trend toward improved alignment with increasing canal fill, suggesting that uncemented diaphyseal engaging press-fit modular stems facilitate accurate alignment for both femoral and tibial components in revision surgery.

Periprosthetic Joint Infection Is the Main Cause of Failure for Modern Knee Arthroplasty: An Analysis of 11,134 Knees

BackgroundAlthough large series from national joint registries may accurately reflect indications for revision TKAs, they may lack the granularity to detect the true incidence and relative importance of such indications, especially periprosthetic joint infections (PJI).Questions/purposesUsing a combination of individual chart review supplemented with New Zealand Joint Registry data, we asked: (1) What is the cumulative incidence of revision TKA? (2) What are the common indications for revising a contemporary primary TKA? (3) Do revision TKA indications differ at various followup times after primary TKA?MethodsWe identified 11,134 primary TKAs performed between 2000 and 2015 in three tertiary referral hospitals. The New Zealand Joint Registry and individual patient chart review were used to identify 357 patients undergoing subsequent revision surgery or any reoperation for PJI. All clinical records, radiographs, and laboratory results were reviewed to identify the primary revision reason. The cumulative incidence of each revision reason was calculated using a competing risk estimator.ResultsThe cumulative incidence for revision TKA at 15 years followup was 6.1% (95% CI, 5.1%–7.1%). The two most-common revision reasons at 15 years followup were PJI followed by aseptic loosening. The risk of revision or reoperation for PJI was 2.0% (95% CI, 1.7%–2.3%) and aseptic loosening was 1.2% (95% CI, 0.7%–1.6%). Approximately half of the revision TKAs secondary to PJI occurred within 2 years of the index TKA (95% CI, 0.8%–1.2%), whereas half of the revision TKAs secondary to aseptic loosening occurred 8 years after the index TKA (95% CI, 0.4%–0.7%).ConclusionsIn this large cohort of patients with comprehensive followup of revision procedures, PJI was the dominant reason for failure during the first 15 years after primary TKA. Aseptic loosening became more important with longer followup. Efforts to improve outcome after primary TKA should focus on these areas, particularly prevention of PJI.Level of EvidenceLevel III, therapeutic study.