Rodilla / Knee: difícil aloinjerto para la rotura del mecanismo extensor

Extensor mechanism allograft reconstruction for extensor mechanism failure following total knee arthroplasty.

Brown NM, Murray T, Sporer SM, Wetters N, Berger RA, Della Valle CJ.

J Bone Joint Surg Am. 2015 Feb 18;97(4):279-83. doi: 10.2106/JBJS.N.00759.

Abstract

BACKGROUND: Extensor mechanism disruption following total knee arthroplasty is a rare but devastating complication. The purpose of this study was to report our experience with extensor mechanism allograft reconstruction for chronic extensor mechanism failure.

METHODS: Fifty consecutive extensor mechanism allograft reconstructions were performed in forty-seven patients with a mean age of 67.6 years who were followed for a mean time of 57.6 months (range, twenty-four to 125 months). The operative technique included the use of a fresh-frozen, correctly sized full extensor mechanism allograft that was tensioned tightly in full extension. Patients were evaluated clinically with use of the Knee Society score, and reconstructions were considered failures if the patient had a score of <60 points or a recurrent extensor lag of >30° or if they required revision or removal of the allograft.

RESULTS: Nineteen reconstructions (38%) were considered failures, including four revised to a second extensor mechanism allograft due to failure of the allograft, five for deep infection, and ten considered clinical failures secondary to a Knee Society score of <60 points or an extensor lag of >30°. The mean Knee Society score improved from 33.9 to 75.9 points (p < 0.0001). The estimated Kaplan-Meier survivorship with failure for any reason as the end point was 56.2% (95% confidence interval, 39.4% to 70.1%) at ten years.

CONCLUSIONS: Extensor mechanism disruption following total knee arthroplasty is a difficult complication to treat, with modest outcomes. Extensor mechanism allograft reconstruction is a reasonable option; however, patients must be informed regarding the substantial risk of complications, and although initial extensor mechanism function may be restored, expectations regarding longer-term outcomes are more guarded.

LEVEL OF EVIDENCE: Therapeutic Level IV

Rodilla/Knne: Van peor las PTR en enfermos con lesiones menos graves

Chronic non-orthopedic conditions more common in patients with less severe degenerative changes that have elected to undergo total knee arthroplasty

Cale A. Jacobs, Christian P. Christensen, Tharun Karthikeyan
J Arthroplasty: Published Online: February 06, 2015

DOI: http://dx.doi.org/10.1016/j.arth.2015.01.051

The purpose of this study was to determine whether the prevalence of chronic non-orthopedic conditions that may play a role in an abnormal pain response differ between patients based on the severity of degenerative changes at the time of surgery.

Of 1,020 OA knees that had undergone primary TKA with a minimum 2 year follow-up, we identified 117 (11.5%) that had less severe degenerative changes. The prevalence of dissatisfaction was significantly greater in less severe group compared to those with moderate or severe changes (18.8% vs. 9.3%, p = .003). Chronic non-orthopedic conditions were significantly more prevalent in the less severe group with 41.9% reporting depression/anxiety, 30.8% with fibromyalgia or low back pathology, and 12.8% with a prior traumatic brain injury or stroke.

Rodilla/Knee: Ahorrar reinfusión de sangre con tranexámico

Effect of a Single Injection of Tranexamic Acid on Blood Loss after Primary Hybrid TKA

Yoshinori Ishii, Hideo Noguchi, Junko Sato, Chiduru Tsuchiya, Shin-ichi Toyabe

The Knee
Available online 17 January 2015

Background
Control of perioperative blood loss is important in total knee arthroplasty (TKA), especially cementless or hybrid TKA. There is increasing interest in the use of tranexamic acid (TXA) for this purpose; however, studies to date have mainly evaluated the effects of various TXA administration regimens on patients who underwent cemented TKA. We sought to determine (1) whether administration of TXA reduces blood loss after hybrid TKA, and (2) whether an autologous blood reinfusion system is necessary in TKA patients who are treated with TXA.

Methods
Ninety-five patients (100 knees) who underwent hybrid primary TKA (cemented tibia, uncemented femur) were included in this study. The initial 50 knees were treated without TXA and the following 50 were treated with TXA. Intravenous TXA (1000mg) was administered shortly before deflation of the tourniquet. All continuous variables are expressed as median values.

Results
Total volumes of blood lost at postoperative 1day were 590ml and 150ml and autotransfusion of collected blood was performed in 88 % and 16% of patients in the without and with TXA groups, respectively. A median volume of 400ml of collected blood was returned to the patients in the without TXA group, and 0ml to the patients in the with TXA group. The calculated volumes of blood lost were 761ml and 683ml (p=0.2250), respectively.

Conclusions
One intravenous injection of 1000mg TXA may help to control postoperative blood loss and reduce the need for postoperative autologous blood reinfusion after hybrid TKA.

Levels of evidence: Level II. 

Rodilla/Knee: Se supone que deberíamos avanzar

Are outcomes after total knee arthroplasty worsening over time? A time-trends study of activity limitation and pain outcomes

Singh JA, Lewallen DG

BMC Musculoskelet Disord 2014.:440.

Abstract

BACKGROUND

To examine whether function and pain outcomes of patients undergoing primary total knee arthroplasty (TKA) are changing over time.

METHODS

The Mayo Clinic Total Joint Registry provided data for time-trends in preoperative and 2-year post-operative activity limitation and pain in primary TKA patients from 1993-2005. We used chi-square test and analysis for variance, as appropriate. Multivariable-adjusted analyses were done using logistic regression.

RESULTS

In a cohort of 7,229 patients who underwent primary TKA during 1993-2005, mean age was 68.4 years (standard deviation (SD), 9.8), mean BMI was 31.1 (SD, 6.0) and 55% were women. Crude estimates showed that preoperative moderate-severe overall limitation were seen in 7.3% fewer patients and preoperative moderate-severe pain in 2.7% more patients in 2002-05, compared to 1992-95 (p < 0.001 for both). At 2-years, crude estimates indicated that compared to 1992-95, moderate-severe post-TKA overall limitation was seen in 4.7% more patients and moderate-severe post-TKA pain in 3.6% more patients in 2002-05, both statistically significant (p ≤ 0.018) and clinically meaningful. In multivariable-adjusted analyses that adjusted for age, sex, anxiety, depression, Deyo-Charlson index, body mass index and preoperative pain/limitation, patients had worse outcomes 2-year post-TKA in 2002-2005 compared to 1993-95 with an odds ratio (95% confidence interval (CI); p-value) of 1.34 (95% CI: 1.02, 1.76, p = 0.037) for moderate-severe activity limitation and 1.79 (95% CI: 1.17, 2.75, p = 0.007) for moderate-severe pain.

CONCLUSION

Patient-reported function and pain outcomes after primary TKA have worsened over the study period 1993-95 to 2002-05. This time-trend is independent of changes in preoperative pain/limitation and certain patient characteristics.

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4301928/pdf/

Rodilla/Knee: Las tendencias en las PTR

Trends in Total Knee Arthroplasty Implant Utilization.
Nguyen LC, Lehil MS, Bozic KJ
J Arthroplasty. 2014 Dec 13. pii: S0883-5403(14)00940-1. doi: 10.1016/j.arth.2014.12.009. [Epub ahead of print]

Abstract

The incidence of total knee arthroplasty (TKA) has increased alongside our knowledge of knee physiology, kinematics, and technology resulting in an evolution of TKA implants. This study examines the trends in TKA implant utilization. Data was extracted from The Orthopedic Research Network to evaluate trends in level of constraint, fixed vs. mobile bearing, fixation, and type of polyethylene in primary TKAs. In 2012, 88% used cemented femoral and tibial implants, and 96% involved patellar resurfacing. 38% of implants were cruciate retaining, 53% posterior stabilized or condylar stabilized, 3% constrained. 91% were fixed-bearing, 7% mobile-bearing. 52% of tibial inserts were HXLPE. TKA implant trends demonstrate a preference for cemented femoral and tibial components, patellar resurfacing, fixed-bearing constructs, metal-backed tibial components, patellar resurfacing, and increased usage of HXLPE liners.

KEYWORDS:

Rodilla/Knee: Más bien, rotando hacia afuera

Influence of tibial rotation in total knee arthroplasty on knee kinematics and retropatellar pressure: an in vitro study
Arnd Steinbrück, Christian Schröder, Matthias Woiczinski, Tatjana Müller, Peter E Müller, Volkmar Jansson, Andreas Fottner
Knee Surg Sports Traumatol Arthrosc. 2015 Jan 11. [Epub ahead of print]

PURPOSE: Although continuous improvements have been made, there is still a considerable amount of unsatisfied patients after total knee arthroplasty (TKA). A main reason for this high percentage is anterior knee pain, which is supposed to be provoked by post-operative increased retropatellar peak pressure. Since rotational malalignment of the implant is believed to contribute to post-operative pain, the aim of this study was to examine the influence of tibial component rotation on knee kinematics and retropatellar pressure.

METHODS: Eight fresh-frozen knee specimens were tested in a weight-bearing knee rig after fixed-bearing TKA under a loaded squat from 20° to 120° of flexion. To examine tibial components with different rotations, special inlays with 3° internal rotation and 3° external rotation were produced and retropatellar pressure distribution was measured with a pressure-sensitive film. The kinematics of the patella and the femorotibial joint were recorded with an ultrasonic-based motion analysis system.

RESULTS: Retropatellar peak pressure decreased significantly from 3° internal rotation to neutral position and 3° external rotation of the tibial component (8.5 ± 2.3 vs. 8.2 ± 2.4 vs. 7.8 ± 2.5 MPa). Regarding knee kinematics femorotibial rotation and anterior-posterior translation, patella rotation and tilt were altered significantly, but relative changes remained minimal.

CONCLUSION: Changing tibial rotation revealed a high in vitro influence on retropatellar peak pressure. We recommend the rotational alignment of the tibial component to the medial third of the tibial tuberosity or even more externally beyond that point to avoid anterior knee pain after TKA.

Rodilla/Knee: Sin diferencias de riesgo de revisión con distintos polietilenos

Is There a Difference in Total Knee Arthroplasty Risk of Revision in Highly Crosslinked versus Conventional Polyethylene?

Paxton EW, Inacio MC, Kurtz S, Love R, Cafri G, Namba RS.

Clin Orthop Relat Res. 2015 Jan 8. [Epub ahead of print]

Abstract

BACKGROUND: 

Highly crosslinked polyethylene (HXLPE) was introduced to reduce wear and associated osteolysis in total knee arthroplasty (TKA). However, there is limited clinical evidence that HXLPE is more effective than conventional polyethylene (CPE) in TKA.

QUESTIONS/PURPOSES: 

(1) Do primary TKAs with HXLPE tibial inserts have a lower risk of revision (all-cause, aseptic, and septic) than TKAs with CPE tibial inserts? (2) In NexGen TKA (Zimmer Inc, Warsaw, IN, USA) bearings, do HXLPE tibial inserts have a lower risk of revision (all-cause, aseptic, and septic) than CPE tibial inserts? (3) In Press-Fit Condylar TKA (PFC or PFC Sigma; DePuy Inc, Warsaw, IN, USA), do HXLPE tibial inserts have a lower risk of revision (all-cause, aseptic, and septic) than procedures performed with CPE tibial inserts?

METHODS: 

The Kaiser Permanente Total Joint Replacement Registry was used to identify primary TKAs (N = 77,084) performed during the study period (April 2001 to December 2011) with cobalt-chromium alloy on CPE (CoCr-CPE) and CoCr-HXLPE bearings. The registry has 95% voluntary participation and less than 9% were loss to followup during the 10-year study period. A total of 60,841 (79%) had CoCr-CPE bearings, 11,048 (14%) had CoCr-HXLPE bearings, and 5195 (7%) were unknown. Specific knee implant designs (NexGen, Zimmer and PFC-Sigma, DePuy Inc) were also evaluated. These implants represented 41% (31,793) and 49% (37,457), respectively, of the 77,084 TKAs of known implant types registered during that period; implant selection was at the discretion of the attending surgeon. Descriptive statistics and marginal Cox regression models with propensity score adjustments were applied to compare risk of revision for CoCr-CPE versus CoCr-HXLPE TKA bearings.

RESULTS: 

At 5 years followup, cumulative incidence of revision for CoCr-CPE and CoCr-XLPE were 2.7% and 3.1%, respectively. Adjusted risks of all-cause (hazard ratio [HR], 1.05; 95% confidence interval [CI], 0.86-1.29; p = 0.620), aseptic (HR, 1.01; 95% CI, 0.77-1.32; p = 0.954), and septic revision (HR, 1.11; 95% CI, 0.81-1.51; p = 0.519) did not differ in patients with CoCr-XLPE bearings compared with CoCr-CPE. Within TKAs with NexGen components, the adjusted risks of all-cause (HR, 1.14; 95% CI, 0.86-1.51; p = 0.354), aseptic (HR, 1.14; 95% CI, 0.79-1.65; p = 0.493), and septic revision (HR, 1.14; 95% CI, 0.76-1.73; p = 518) were similar in patients with CoCr-XLPE compared with those with CoCr-CPE bearings. Finally, within the TKAs with PFC components, the adjusted risks of all-cause (HR, 0.80; 95% CI, 0.49-1.30; p = 0.369), aseptic (HR, 0.62; 95% CI, 0.62-1.14; p = 0.123), and septic revision (HR, 0.97; 95% CI, 0.51-1.85; p = 0.929) were also similar in patients with CoCr-XLPE compared with those with CoCr-CPE bearings.

CONCLUSIONS: 

In this large study, we did not find differences in risk of revision for CoCr-HXLPE compared with CoCr-CPE bearings at 5 years followup. In selecting HXLPE in TKA, clinicians should consider the increased cost and lack of available evidence of performance for greater than 10 years followup. Future studies are necessary to evaluate longitudinal outcomes of CoCr-HXLPE versus conventional TKA bearings.

LEVEL OF EVIDENCE: 

Level III, therapeutic study. 

Rodilla/Knee/Knie/Genou:¿Con menos complicaciones de lo imaginado?

The John Insall Award: Morbid Obesity Independently Impacts Complications, Mortality, and Resource Use After TKA
Michele R D'Apuzzo, Wendy M Novicoff, James A Browne
Clinical Orthopaedics and related Research 2015, 473 (1): 57-63

BACKGROUND: The importance of morbid obesity as a risk factor for complications after total knee arthroplasty (TKA) continues to be debated. Obesity is rarely an isolated diagnosis and tends to cluster with other comorbidities that may independently lead to increased risk and confound outcomes. It is unknown whether morbid obesity independently affects postoperative complications and resource use after TKA.

QUESTIONS/PURPOSES: The purpose of this study was to determine whether morbid obesity is an independent risk factor for inpatient postoperative complications, mortality, and increased resource use in patients undergoing primary TKA.

METHODS: The Healthcare Cost and Utilization Project Nationwide Inpatient Sample (NIS) database was used to identify patients undergoing primary TKA from October 2005 to December 2008. Morbid obesity (body mass index ≥ 40 kg/m(2)) was determined using International Classification of Diseases, 9(th) Revision, Clinical Modification codes. In-hospital postoperative complications, mortality, costs, and disposition for morbidly obese patients were compared with nonobese patients. To control for potential confounders and comorbid conditions, each morbidly obese patient was matched to a nonobese patient using age, sex, and all 28 comorbid-defined elements in the NIS database based on the Elixhauser Comorbidity Index. Of 1,777,068 primary TKAs, 98,410 (5.5%) patients were categorized as morbidly obese. Of these, 90,045 patients (91%) were able to be matched one-to-one to a nonobese patient for the adjusted analysis.

RESULTS: Morbidly obese patients had a higher risk of postoperative in-hospital infection (0.24% versus 0.17%; odds ratio [OR], 1.3; 95% confidence interval [CI], 1.1-1.7; p = 0.001), wound dehiscence (0.11% versus 0.08%; OR, 1.3; 95% CI, 1.0-1.7; p = 0.28), and genitourinary-related complications (0.60% versus 0.44%; OR, 1.3; 95% CI, 1.1-1.5; p < 0.001). There was no increase in the prevalence of cardiovascular or thromboembolic-related complications. Morbidly obese patients were at higher risk of in-hospital death after primary TKA compared with nonobese patients (0.08% versus 0.02%; OR, 3.2; 95% CI, 2.0-5.2; p < 0.001). Total hospital costs (USD 15,174 versus USD 14,715, p < 0.001), length of stay (3.6 days versus 3.5 days, p < 0.001), and rate of discharge to a facility (40% versus 30%, p < 0.001) were all higher in morbidly obese patients.

CONCLUSIONS: Morbid obesity appears to be independently associated with a higher risk for a small number of select in-hospital postoperative complications and mortality after matching for comorbid medical conditions linked to obesity. However, the independent impact of morbid obesity appears to be fairly modest, and morbid obesity did not appear to be an independent risk factor for many systemic complications. Continued research is necessary to identify the influence of associated comorbidities on early postoperative complications in morbidly obese patients after TKA.

LEVEL OF EVIDENCE: Level II, prognostic study.

Rodilla/Knee: Tendencias de una década

Trends in Total Knee Arthroplasty Implant Utilization
Long-Co L. Nguyen, Mandeep Lehil, Kevin J. Bozic
The Journal of Arthroplasty
Published Online: December 13, 2014
DOI: http://dx.doi.org/10.1016/j.arth.2014.12.009

Abstract

The incidence of total knee arthroplasty (TKA) has increased alongside our knowledge of knee physiology, kinematics, and technology resulting in an evolution of TKA implants. This study examines the trends in TKA implant utilization in the United States.

Data from 2001 to 2012 was extracted from The Orthopedic Research Network to evaluate trends in level of constraint, fixed vs. mobile bearing, fixation, and type of polyethylene.

In 2012, 88% of primary TKAs used cemented femoral and tibial implants. 38% of primary TKA implants were cruciate retaining, 53% posterior stabilized or condylar stabilized, 3% constrained. 91% was fixed-bearing, 7% mobile-bearing. 52% of tibial inserts were HXLPE.

TKA implant trends demonstrate a preference for cemented femoral and tibial components, fixed-bearing constructs, the use of metal-backed tibial components, and increased usage of HXLPE liners.

Rodilla/Knee/Knie/Genou: con unos pinchazos no duele la ptr

Periarticular Regional Analgesia in Total Knee Arthroplasty
A Review of the Neuroanatomy and Injection Technique
George N. Guild III, Rubin P. Galindo, Joseph Marino, Fred D. Cushner, Giles R. Scuderi

Orthopedic Clinics
Volume 46, Issue 1, Pages 1–8, January 2015

Perioperative pain control after total knee arthroplasty may be insufficient, resulting in insomnia, antalgic ambulation, and difficulty with rehabilitation. Current strategies, including the use of femoral nerve catheters, may control pain but have been associated with falls, motor blockade, and quadriceps inhibition. Periarticular infiltration using the appropriate technique and knowledge of intraarticular knee anatomy may increase pain control and maximize rehabilitation.

Rodilla/Knee/Knie/Genou: Para qué al año si no mejora la atención

Assessing the utility of routine first annual follow-up visits after primary total knee arthroplasty
Cale A. Jacobs, Christian P. Christensen, Tharun Karthikeyan
The Journal of Arthroplasty
Published Online: November 25, 2014
DOI: http://dx.doi.org/10.1016/j.arth.2014.11.016

Abstract

The combination of increased TKA utilization and a decreased number of arthroplasty specialists has resulted in a growing need to maximize efficiency without sacrificing the level of care being provided. The purpose of this study was to evaluate the utility of routine first annual follow-up visits for patients that have undergone primary TKA. In order to do so, we determined the current follow-up rate for these visits and the number of revisions that were performed for a complication that was first detected at the routine first annual follow-up visit. Of 339 TKAs performed in 2012, 71 patients failed to attend scheduled first annual visits. Furthermore, none of the revisions performed at our facility since 2003 were the direct result of information gained at a patient’s routine first annual visit. As such, we question the clinical utility of the first annual visit and are evaluating an evidence-based follow-up protocol.

Rodilla/Knee/Knie/Genou: No importa si eviertes o separas la rótula

A randomized, controlled, prospective study evaluating the effect of patellar eversion on functional outcomes in primary total knee arthroplasty.
Jenkins D, Rodriguez J, Ranawat A, Alexiades M, Deshmukh A, Fukunaga T, Greiz M, Rathod P, McHugh M.
J Bone Joint Surg Am. 2014 May 21;96(10):851-8

Abstract

BACKGROUND: Patellar mobilization technique during total knee arthroplasty has been debated, with some suggesting that lateral retraction, rather than eversion, of the patella may be beneficial. We hypothesized that patients with knees surgically exposed using patellar lateral retraction would have comparable outcomes with patients with knees surgically exposed using patellar eversion.

METHODS: After an a priori power analysis, 120 patients with degenerative arthrosis were prospectively enrolled and were randomized to one of two patellar exposure techniques during the primary total knee arthroplasty: lateral retraction or eversion. The primary outcome measure was one-year, dynamometer-measured quadriceps strength. The secondary outcome measures evaluated during hospital stay included the ability to straight-leg raise, visual analog scale in pain, walking distance, and length of stay. The secondary outcome measures that were evaluated preoperatively and through a one-year follow-up included the Short Form-36 Physical Component Summary and Mental Component Summary scores, range of motion, quadriceps strength, and radiographic rate of patella baja and tilt.

RESULTS: A mixed-model analysis of variance showed no significant differences between the two groups in the one-year outcome measures. At one year postoperatively, quadriceps strength was not different between groups (p = 0.77), and the range of motion significantly improved (p &lt; 0.01) from preoperative values by a mean value (and standard deviation) of 6° ± 17°, with no significant difference (p = 0.60) between groups. The Short Form-36 Physical Component Summary score and Mental Component Summary score significantly improved (p &lt; 0.01) for both study groups from preoperatively to one year postoperatively with no significantly different effects between groups (time × group, p = 0.85 for the Physical Component Summary score and p = 0.71 for the Mental Component Summary score), and the scores were not different at one year after surgery. There were no significant differences between groups in the change in frequency of the radiographic patella baja (p = 0.99) or the radiographic patellar tilt (p = 0.77) from before surgery to one year after surgery.

CONCLUSIONS: Lateral retraction of the patella did not lead to superior postoperative results compared with eversion of the patella during total knee arthroplasty as evaluated using our primary outcome measure of one-year, dynamometer-measured quadriceps strength or our secondary outcome measures.

LEVEL OF-EVIDENCE: Therapeutic Level II

Rodilla/Knee/Knie/Genou: Saber con una rx que la PTR se va a aflojar

Trabecular bone density of the proximal tibia as it relates to failure of a total knee replacement

Ritter, M. A., Davis, K. E., Small, S. R., Merchun, J. G., Farris, A.

Bone Joint J 2014;96-B:1503–9.

The relationship between post-operative bone density and subsequent failure of total knee replacement (TKR) is not known. This retrospective study aimed to determine the relationship between bone density and failure, both overall and according to failure mechanism. 

All 54 aseptic failures occurring in 50 patients from 7760 consecutive primary cemented TKRs between 1983 and 2004 were matched with non-failing TKRs, and 47 failures in 44 patients involved tibial failures with the matching characteristics of age (65.1 for failed and 69.8 for non-failed), gender (70.2% female), diagnosis (93.6% OA), date of operation, bilaterality, pre-operative alignment (0.4 and 0.3 respectively), and body mass index (30.2 and 30.0 respectively). In each case, the density of bone beneath the tibial component was assessed at each follow-up interval using standardised, calibrated radiographs. Failing knees were compared with controls both overall and, as a subgroup analysis, by failure mechanism. Knees were compared with controls using univariable linear regression.

Significant and continuous elevation in tibial density was found in knees that eventually failed by medial collapse (p < 0.001) and progressive radiolucency (p < 0.001) compared with controls, particularly in the medial region of the tibia. Knees failing due to ligamentous instability demonstrated an initial decline in density (p = 0.0152) followed by a non-decreasing density over time (p = 0.034 for equivalence). Non-failing knees reported a decline in density similar to that reported previously using dual-energy x-ray absorptiometry (DEXA). 

Differences between failing and non-failing knees were observable as early as two months following surgery. This tool may be used to identify patients at risk of failure following TKR, but more validation work is needed.

Rodilla/Knee/Knie/Genou: algunas prótesis no son tan modélicas

Evidence of trochlear dysplasia in femoral component designs.

Dejour D, Ntagiopoulos PG, Saffarini M.

Knee Surg Sports Traumatol Arthrosc. 2014 Nov;22(11):2599-607.

Abstract

PURPOSE:

The study aimed to compare trochlear profiles of various total knee arthroplasty (TKA) models to anatomic profiles observed in healthy and pathologic knees and to evaluate trochlear designs against radiologic indicators for PF disorders and trochlear dysplasia.

METHODS:

The trochlear profiles of 14 different TKA models were digitized using a coordinate measurement machine at various flexion angles (0°, 15°, 30° and 45°) to deduce the following variables: sulcus angle, trochlear groove orientation, height of lateral facet, and mediolateral groove position. The effect of externally rotating the femoral component on those variables was simulated.

RESULTS:

The sulcus angle was greater than the indicators for trochlear dysplasia of 144° in 11 implants at 45° flexion, and in 13 implants at 30° flexion. The lateral facet height was less than average anatomic values of 5 mm in eight specimens through the entire range of early flexion (0°-30°). The trochlear groove was oriented laterally in 13 specimens (3.3°-11.7°) and was vertical in one specimen (0.3°). Applying an external rotation up to 6° resulted in noticeable lateral translation of the trochlear groove and facets, but negligible posterior translation.

CONCLUSIONS:

The study presented a detailed description of previously overlooked TKA design parameters and revealed that some femoral components exhibit characteristics of trochlear dysplasia. The clinical relevance of this descriptive study is that surgeons should be aware of such design limitations to improve choice of implant for patients with history of PF disorders and to adapt surgical techniques as necessary to optimize PF tracking.

LEVEL OF EVIDENCE:

Case-control study, Level III.

Rodilla/Knee/Knie/Genou: 30 años después de la PTR

Total Knee Replacement in Young, Active Patients: Long-Term Follow-up and Functional Outcome: A Concise Follow-up of a Previous Report
Long, W. J., Bryce, C. D., Hollenbeak, C. S., Benner, R. W., Scott, W. N.
The Journal of Bone & Joint Surgery, 17 Septiembre 2014 19:30

Abstract:

Concern exists regarding the long-term durability and effectiveness of total knee arthroplasty in young patients.

We reviewed our experience with total knee arthroplasty in patients fifty-five years old and younger with severe osteoarthritis to determine the long-term outcomes. One hundred and fourteen total knee arthroplasties were performed in eighty-eight patients at an average patient age of fifty-one years. Clinical outcomes, survival analysis, and radiographs were all reviewed at the most recent follow-up. One hundred and eight knees (eighty-four patients) were followed up from May 2011 to 2012.

At thirty years, survivorship without revision for any cause was 70.1% (twenty-five revisions) and survivorship with failure defined as aseptic revision of the tibial or femoral components was 82.5%. At thirty years, a significant difference existed in the survivorship free from tibial or femoral aseptic revision (p = 0.003) between the non-modular Insall-Burstein I component (92.3%) and the modular Insall-Burstein II component (68.3%). All patients were evaluated at an average time from the index total knee arthroplasty to the latest follow-up of 25.1 years (range, twenty to thirty-five years). Clinical evaluation was obtained in thirty-six patients with forty-five total knee arthroplasties. The average Hospital for Special Surgery score had improved from 57.9 points preoperatively to 85.3 points. The average Knee Society score was 87.4 points and the average Knee Society functional score was 62.1 points; the average knee motion was 110°. The mean Tegner and Lysholm activity score improved from 1.5 points preoperatively to 3.0 points. Radiographic review of forty-two knees that had undergone total knee arthroplasty demonstrated a mean 3.2° of valgus, with no cases of radiographically loose components.

Total knee arthroplasty with use of a cemented posterior stabilized system, particularly a non-modular Insall-Burstein I design, was an effective treatment option with durable results for end-stage symptomatic osteoarthritis in this young cohort. These data should provide comparison for modern total knee arthroplasties and alternative procedures in young patients.

Level of Evidence:
Therapeutic Level IV

Rodilla/Knee/Knie/Genou: Cuando la rótula no encaja... hay remedios

Medial patellofemoral ligament reconstruction for patellar maltracking following total knee arthroplasty is effective
Stijn van Gennip, Janneke J P Schimmel, Gijs G van Hellemondt, Koen C Defoort, Ate B Wymenga
Knee Surgery, Sports Traumatology, Arthroscopy: Official Journal of the ESSKA 2014, 22 (10): 2569-73

PURPOSE: Maltracking of the patella after total knee arthroplasty (TKA) remains a well-recognized problem. The medial patellofemoral ligament (MPFL) has shown to be important for patellar stabilization and reconstructions of the MPFL have already shown excellent functional outcomes for patellar instability of the native knee. Nevertheless, there is only limited literature on using an MPFL reconstruction for correction of patellar maltracking after TKA. In this retrospective study, a consecutive case series was evaluated.

METHODS: Between 2007 and 2010, nine patients (nine knees) with anterior knee pain and symptomatic (sub)luxations of the patella after primary or revision TKA were treated by reconstruction of the MPFL in combination with a lateral release. In two cases, an additional tibial tuberosity transfer was performed, due to insufficient per-operative correction. Pre-operative work-up included a CT scan to rule out component malrotation and disorders in limb alignment. Pre- and post-operative patellar displacement and lateral patellar tilt were measured on axial radiographs. Clinical outcome was evaluated using the visual analogue scale (VAS) satisfaction, VAS pain, dislocation rate and Bartlett patella score.

RESULTS: Median patellar displacement improved from 29 mm (0-44) to 0 mm (0-9) post-operatively. Median lateral patellar tilt was 45° (23-62) pre-operative and changed to a median 15° (-3 to 21) post-operative. Median VAS satisfaction was 8 (5-9) and only one patient reported a subluxing feeling afterwards. The Bartlett patella score displayed a diverse picture.

CONCLUSIONS: Patellar maltracking after primary or revision TKA without malrotation can effectively be treated by MPFL reconstruction in combination with a lateral release. Only in limited cases, an additional tibial tuberosity transfer is needed.

LEVEL OF EVIDENCE: IV.

Rodilla/Knee/Knie/Genou: Monocitos para establecer una sinovitis por desgaste del polietileno

Synovial fluid differential cell count in wear debris synovitis after total knee replacement
Ran Schwarzkopf , Evan M. Carlson , Meagan E. Tibbo , Lee Josephs , Richard D. Scott
The Knee: Available online 28 July 2014

Background
Determining the cause of synovitis following total knee arthroplasty (TKA) can be challenging. The differential diagnoses include infection, hemarthrosis, instability, crystalline disease, wear debris or idiopathic causes. Wear particle synovitis can mimic periprosthetic infection with symptoms of pain and effusion. Radiographs and physical exam are often inconclusive in differentiating the two. Synovial fluid analysis is routinely used in evaluating periprosthetic infections. We examined the association between synovial white blood cell count and differentials, and polyethylene wear and osteolysis, to see if fluid analysis can aid in establishing the diagnosis of wear particle synovitis.

Methods
A cell count and differential was obtained from synovial fluid samples from 54 TKAs undergoing revision for aseptic failure. Explanted polyethylene inserts were analyzed for linear and volumetric wear, oxidation (ketone peak height), and damage features. Analysis was performed to assess the relationship between cell counts and polyethylene wear indicators as well as severity of intra-operative and radiographic osteolysis.

Results
Total and percent mononuclear (monocyte and lymphocyte) cell counts were found to be elevated in the presence of documented wear debris synovitis and an association was suggested between their levels and maximum ketone levels.

Conclusion
The present study implies that the differential cell count of knee fluid can help distinguish wear debris from infection as a source of synovitis following TKA and identifies the value of the mononuclear cell count as a possible tool to assess abnormal wear rates of the polyethylene insert. Further research into identifying the exact role of monocytes in the wear debris synovitis and osteolytic pathways is warranted.

Level of evidence
Level II, diagnostic study.

Rodilla/Knee/Knie: Hay que evitar la PTR en verano

Seasonality of infection rates after total joint arthroplasty.

Kane P, Chen C, Post Z, Radcliff K, Orozco F, Ong A

Orthopedics February 2014 - Volume 37 · Issue 2: e182-e186

Abstract

The correlation between season (fall, winter, spring, and summer) and infection rate in surgical patients is well defined in many specialties. To the authors' knowledge, there are no data in the literature on this phenomenon in patients undergoing total joint arthroplasty. They hypothesized that there would be an increased infection rate in the summer months in patients undergoing elective total joint arthroplasty. They retrospectively reviewed consecutive patients undergoing elective total hip or knee arthroplasty at a single institution during 1 year by a single surgeon. Wound infections were defined as any patient requiring oral antibiotics for cellulitis, readmission for intravenous antibiotics, a return to the operating room for irrigation and debridement, or excisional arthroplasty and placement of a cement spacer within 90 days of the initial procedure. Seventeen of 750 patients developed an infection, for an overall incidence of 2.2%. There was a statistically significant difference in infection rate according to season: 3 (1.5%) infections occurred in winter, 1 (0.5%) in spring, 9 (4.7%) in summer, and 4 (2.4%) in fall. The incidence was highest during July (4.5%), August (5.4%), and September (4.3%). There was a statistically significant difference in infection rate between summer/fall (3.6%) vs winter/spring (1.0%). There is an increase in the incidence of infection during summer months for patients undergoing total joint arthroplasty. The authors recommend increased surveillance and more thorough preoperative sterilization procedures during these warmer months

Rodilla/Knee/Knie: Cemento el justo

Can Cementing Technique Reduce the Cost of a Primary Total Knee Arthroplasty?

Maheshwari A, Argawal M, Naziri Q, Pivec R, Mont MA, Rasquinha VJ

J Knee Surg 2014 Apr 21.

Abstract

Studies on cost containment of total knee arthroplasty (TKA) have generated substantial interest over the past decade. Although multiple studies have evaluated the various intraoperative methods to control cost, no prior study has evaluated the economic impact and the clinical outcome based on amount of bone cement needed for a primary TKA. At a minimum of 3 years follow-up, we observed no difference in implant survivorship or Knee Society scores, but did observe substantial cost savings when one versus two packets of bone cement were used in combination with a hand mixing technique. By eliminating several extra cement mixing products, we achieved an approximately $1,000 cost saving per case with no difference in clinical outcomes at midterm follow-up.

Rodilla/Knee/Knie: Es clínicamente irrelevante respetar o sacrificar el LCP

Retention versus sacrifice of the posterior cruciate ligament in total knee arthroplasty for treating osteoarthritis.

Verra WC1, van den Boom LG, Jacobs W, Clement DJ, Wymenga AA, Nelissen RG.

Cochrane Database Syst Rev. 2013 Oct 11;10:CD004803

Abstract

BACKGROUND:

The functional and clinical basis on which to choose whether or not to retain the posterior cruciate ligament during total knee arthroplasty surgery remained unclear after a Cochrane systematic review and meta-analysis in 2005, which contained eight clinical trials. Several new trials have been conducted since then. Hence, an update of the review was performed.

OBJECTIVES:

Our aim was to assess the benefits and harms of retention compared to sacrifice of the posterior cruciate ligament in total knee arthroplasty in patients with osteoarthritis of the knee.

SEARCH METHODS:

An extensive search was conducted in CENTRAL, MEDLINE (PubMed), EMBASE, Web of Science, CINAHL, Academic Search Premier, Current Contents Connect and Science Direct. All databases were searched, without any limitations, up to 6 December 2012. References of the articles were checked and citation tracking was performed.

SELECTION CRITERIA:

Randomised and quasi-randomised controlled trials comparing retention with sacrifice of the posterior cruciate ligament in primary total knee arthroplasty in patients with osteoarthritis of the knee.

DATA COLLECTION AND ANALYSIS:

Data were collected with a pre-developed form. Risk of bias was assessed independently by two authors (WV, LB). The level of evidence was graded using the GRADE approach. Meta-analysis was performed by pooling the results of the selected studies, when possible. Subgroup analyses were performed for posterior cruciate ligament retention versus sacrifice using the same total knee arthroplasty design, and for studies using a posterior cruciate ligament retaining or posterior stabilised design, and when sufficient studies were available subgroup analyses were performed for the same brand.

MAIN RESULTS:

Seventeen randomised controlled trials (with 1810 patients and 2206 knees) were found, described in 18 articles. Ten of these were new studies compared to the previous Cochrane Review. One study from the original Cochrane review was excluded. Most new studies compared a posterior cruciate ligament retaining design with a posterior stabilised design, in which the posterior cruciate ligament is sacrificed (a posterior stabilised design has an insert with a central post which can engage on a femoral cam during flexion).The quality of evidence (graded with the GRADE approach) and the risk of bias were highly variable, ranging from moderate to low quality evidence and with unclear or low risk of bias for most domains, respectively.The performance outcome 'range of motion' was 2.4 ° higher in favour of posterior cruciate ligament sacrifice (118.3 ° versus 115.9 °; 95% confidence interval (CI) of the difference 0.13 to 4.67; P = 0.04), however the results were heterogeneous. On the item 'knee pain' as experienced by patients, meta-analysis could be performed on the Knee Society knee pain score; this score was 48.3 in both groups, yielding no difference between the groups. Implant survival rate could not be meta-analysed adequately since randomised controlled trials lack the longer term follow-up in order to evaluate implant survival. A total of four revisions in the cruciate-retention and four revisions in the cruciate-sacrifice group were found. The well-validated Western Ontario and McMaster Universities osteoarthritis index (WOMAC) total score was not statistically significantly different between the groups (16.6 points for cruciate-retention versus 15.0 points for cruciate-sacrifice). One study reported a patient satisfaction grade (7.7 points for cruciate-retention versus 7.9 points for cruciate-sacrifice on a scale from 0 to 10, 10 being completely satisfied) which did not differ statistically significantly. Complications were distributed equally between both groups. Only one study reported several re-operations other than revision surgery; that is patella luxations, surgical manipulation because of impaired flexion.The mean functional Knee Society Score was 2.3 points higher (81.2 versus 79.0 points; 95% CI of the difference 0.37 to 4.26; P = 0.02) in the posterior cruciate ligament sacrificing group. Results from the outcome Knee Society functional score were homogeneous. All other outcome measures (extension angle, knee pain, adverse effects, clinical questionnaire scores, Knee Society clinical scores, radiological rollback, radiolucencies, femorotibial angle and tibial slope) showed no statistically significant differences between the groups. In the subgroup analyses that allowed pooling of the results of the different studies, no homogeneous statistically significant differences were identified.

AUTHORS' CONCLUSIONS:

The methodological quality and the quality of reporting of the studies were highly variable. With respect to range of motion, pain, clinical, and radiological outcomes, no clinically relevant differences were found between total knee arthroplasty with retention or sacrifice of the posterior cruciate ligament. Two statistically significant differences were found; range of motion was 2.4 ° higher in the posterior cruciate ligament sacrificing group, however results were heterogeneous; and the mean functional Knee Society Score was 2.3 points higher in the posterior cruciate ligament sacrificing group. These differences are clinically not relevant.