Anatomical site of radiographic degeneration is an independent variable influencing outcome of total knee arthroplasty.

OBJECTIVES: We aimed to determine whether the site of anatomical degenerative change could be identified as an independent risk factor influencing clinical outcome of total knee arthroplasty (TKA) 12 months postoperatively. METHODS: We compared preoperative, postoperative and the change observed in Oxford Knee Score (OKS) amongst TKA patients categorised as primarily medial, lateral or patellofemoral osteoarthritis (PFJOA). Multivariable regression analysis was conducted on 434 consecutive knees in 333 patients, adjusting for sex, age and body mass index (BMI). RESULTS: Adjusted estimates showed that preoperatively, patients with medial and lateral osteoarthritis (OA) had a lower mean OKS of 2.1 (p â€‹= â€‹0.049) and 2.3 (p â€‹= â€‹0.056) points respectively, while those with PFJOA had mean scores 2.7 points higher (p â€‹= â€‹0.062). There was no statistically significant difference between compartments in absolute postoperative OKS. The greatest improvement of 30.1 points (95% confidence interval (CI) 16.9-36.0, p â€‹= â€‹0.012) in OKS was observed for those with lateral OA, followed by 28.9 points (95% CI 16.7-35.3, p â€‹= â€‹0.049) for those with medial OA. The improvement observed postoperatively in patients with PFJOA was less than that observed for the average of the cohort at 24.5 (95% CI 11.5-29.7, p â€‹= â€‹0.088). CONCLUSIONS: The site of compartmental involvement in knee OA is an independent factor influencing clinical outcome of TKA. With arthroplasty registry adoption of patient-reported outcome measures (PROMs), this study supports precise anatomical categorisation of knee OA in outcome studies. LEVEL OF EVIDENCE: Level III, Retrospective consecutive clinical study.

Overstuffing the patellofemoral compartment in total knee arthroplasty: a systematic review.

Purpose: To systematically review and analyze the data available in the literature to evaluate the role of patellofemoral overstuffing in affecting clinical outcomes following primary total knee arthroplasty. Methods: A systematic literature review was conducted following the PRISMA guidelines. Only studies including primary total knee arthroplasty in the setting of osteoarthritis with a quantifiable method of measuring patellofemoral overstuffing using pre- and post-operative x-rays or advanced imaging, as well as reported subjective and/or objective patient outcomes in relation to patellofemoral overstuffing were included. Extracted data included patellofemoral overstuffing quantitative measurement method, outcome measurements, follow-up, patient demographics, author, and publication details. Descriptive analysis was provided for the available literature. Results: There were six included articles with a total of 2325 TKAs assessed. All papers found no significant effect on clinical outcomes when the amount of PFJ overstuffing was within reason. Conclusion: The amount of overstuffing that routinely takes place seems to be within tolerable limits and does not create a significant difference in clinical outcomes. Nevertheless, it is recommended to recreate the anatomic dimensions of the PFJ in order to best obtain a joint that is within this safe margin of error.

Prospective Outcomes of Cryopreserved Osteochondral Allograft for Patellofemoral Cartilage Defects at Minimum 2-Year Follow-up.

OBJECTIVE: To analyze the clinical outcomes, knee function, and activity level of patients after treatment of full-thickness cartilage defects involving the patellofemoral compartment of the knee with cryopreserved osteochondral allograft. DESIGN: Nineteen patients with cartilage defects involving the patellofemoral compartment were treated. The average age was 31 years (range 15-45 years), including 12 females and 7 males. Patients were prospectively followed using validated clinical outcome measures including Veterans RAND 12-item Health Survey (VR-12), International Knee Documentation Committee (IKDC), Knee Injury and Osteoarthritis Outcome Score (KOOS), and the Tegner activity scale. Graft incorporation was evaluated by magnetic resonance imaging (MRI) or second-look arthroscopy. RESULTS: The cartilage defects included the patella (n = 16) and the femoral trochlea (n = 3). Mean VR-12 scores increased from 31.6 to 46.3 (P < 0.01), mean IKDC increased from 40.0 to 69.7 (P < 0.01), mean KOOS increased from 53.9 to 80.2 (P < 0.01), and mean Tegner scores increased from 3.0 to 4.9 (P < 0.01), at average follow-up of 41.9 months (range 24-62 months). Of the 3 patients who underwent second-look arthroscopy, all demonstrated a well-incorporated graft. Mean MOCART score for the 6 patients with follow-up MRI was 62.5 (range 25-85). The reoperation rate was 21.1% and 2 patients (12.5%) experienced progressive patellofemoral osteoarthritis requiring conversion to patellofemoral arthroplasty. CONCLUSION: Patients with unipolar cartilage defects involving the patellofemoral compartment of the knee can have positive outcomes at minimum 2-year follow-up after surgical treatment with a cryopreserved osteochondral allograft when concomitant pathology is also addressed, but the reoperation rate is high and bipolar cartilage lesions may increase the failure rate.

Do Knee Osteoarthritis Patterns Affect Patient-Reported Outcomes in Total Knee Arthroplasty? Results From an International Multicenter Prospective Study With 3-Year Follow-Up.

BACKGROUND: The aim of this multicenter study is to answer (1) Does patellofemoral osteoarthritis (OA) affect preoperative Knee Injury and Osteoarthritis Outcome Score (KOOS) scores in total knee arthroplasty (TKA)? and (2) Do different OA patterns affect preoperative and postoperative KOOS scores in TKA? METHODS: This international, multicenter prospective study examined 384 TKA patients. Compartmental OA was divided into (1) medial, (2) medial + patellofemoral, (3) lateral, (4) lateral + patellofemoral, (5) medial + lateral (bicompartmental), and (6) medial + lateral + patellofemoral (tricompartmental), based on preoperative anterior-posterior and lateral ± skyline radiographs with Kellgren-Lawrence grade III-IV and joint space width <2.5 mm. KOOS was collected preoperatively, 1 year postoperatively, and 3 years postoperatively. Higher KOOS score represented better clinical state, for example, higher KOOS Pain score indicated less pain. RESULTS: Patellofemoral OA had no effect on preoperative KOOS scores (P > .15). Compared to medial ± patellofemoral OA patients, bicompartmental/tricompartmental OA patients had less preoperative pain (KOOS Pain 7.4, P = .03) and higher daily function (KOOS-ADL [Activities of Daily Living] 7.1, P = .05), and higher 1-year postoperative daily function (KOOS-ADL 9.2, P = .03) and sports activity (KOOS Sports & Recreation Function 15.0, P = .04), while lateral ± patellofemoral OA patients had more symptoms (KOOS-Symptoms 7.0, P < .01), more pain (KOOS-Pain 7.5, P = .01), lower daily function (KOOS-ADL 9.3, P < .01), and lower quality of life (KOOS-QOL 9.0, P = .04), at 3 years postoperatively. CONCLUSION: Patellofemoral OA does not affect medial ± lateral OA patients' preoperative KOOS scores, challenging the importance of patellofemoral OA in TKA. Lateral ± patellofemoral OA patients have lower postoperative KOOS scores than medial/more progressed compartmental OA patients, indicating that patients with less common OA patterns present with unique surgical challenges. Further development of indications for and correct timing of TKA surgery in different patient subgroups is needed.

Are There Harmful Effects of Preoperative Mild Lateral or Patellofemoral Degeneration on the Outcomes of Open Wedge High Tibial Osteotomy for Medial Compartmental Osteoarthritis?

BACKGROUND: Early osteoarthritis of the knee joint mostly affects the medial compartment, making osteotomy a rational approach to slow the progression of the disease. However, some patients show asymptomatic mild degeneration in the lateral or patellofemoral compartment. PURPOSE: To evaluate the effect of asymptomatic mild lateral or patellofemoral degeneration on the outcomes of medial open wedge high tibial osteotomy (OWHTO) by assessing the outcomes according to the preoperative status of the lateral or patellofemoral degenerative changes. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: A total of 114 patients (121 knees) who underwent biplanar OWHTO with second-look arthroscopic surgery and postoperative magnetic resonance imaging (MRI) were retrospectively enrolled. Patients were categorized into 4 groups according to the Osteoarthritis Research Society International (OARSI) and MRI Osteoarthritis Knee Score (MOAKS) classification systems. The International Cartilage Repair Society (ICRS) grade was used to evaluate the preoperative and postoperative cartilage status. Clinical outcomes were assessed by the American Knee Society (AKS) score, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and 36-item Short Form Health Survey (SF-36). RESULTS: No degenerative changes in the lateral and patellofemoral compartments of knees (group I) were identified in 51.2% of cases (62 knees). Asymptomatic degenerative changes only in the lateral compartment (group II: OARSI grades 1-3 and MOAKS grades 1-3) were identified in 15.7% of cases (19 knees), changes only in the patellofemoral compartment (group III: OARSI grades 1-3 and MOAKS grades 1-3) were identified in 10.7% of cases (13 knees), and changes in both the lateral and the patellofemoral compartments (group IV) were identified in 22.3% of cases (27 knees). In the medial compartment, there was no significant difference in the improvement of MOAKS and ICRS grades among all groups (P = .813 and .985, respectively). In the lateral and patellofemoral compartments, there was no significant difference in the decline of MOAKS (P = .649 and .421, respectively) and ICRS grades (P = .927 and .676, respectively) among all groups. CONCLUSION: The presence of mild lateral or patellofemoral degenerative changes did not affect the MRI, arthroscopic, and clinical outcomes of OWHTO. However, long-term observations are necessary to draw definitive conclusions as to whether OWHTO can be indicated in such patients without harmful effects.

High tibial osteotomy increases patellofemoral pressure if adverted proximal, while open-wedge HTO with distal biplanar osteotomy discharges the patellofemoral joint: different open-wedge high tibial osteotomies compared to an extra-articular unloading device.

PURPOSE: Valgus high tibial osteotomy (HTO) and a recently introduced extra-articular absorber have been shown to efficiently unload the medial compartment of the knee. However, only little is known about the influence of these treatment modalities on biomechanics of the patellofemoral joint. The purpose of this study was to investigate and compare the impact of different HTO techniques and implantation of an extra-articular absorber on patellofemoral contact forces. METHODS: Fourteen fresh frozen cadaveric knees were tested in a specially designed knee simulator that allowed simulation of isokinetic flexion-extension motions under physiological loading. Mean contact pressure (ACP) and peak contact pressure (PCP) of the patellofemoral joint was measured continuously between 0° and 120° of knee flexion using a pressure sensitive film in the following conditions: native, after biplanar medial open-wedge HTO with 5° and 10° correction angle performing an ascending frontal osteotomy of the tibial tuberosity, and after implantation of an extra-articular absorber system (KineSpring®). Including a second testing cycle with a biplanar medial open-wedge HTO with 5° and 10° correction angle performing descending frontal osteotomy of the tibial tuberosity. Values after each procedure were compared to the corresponding values of the native knee. RESULTS: Biplanar proximal osteotomy leaded to a significant increase of retropatellar compartment area contact pressure compared to the first untreated test cycle (Δ 0.04 ± 0.01 MPa, p = 0.04). Similar results were observed measuring peak contact pressure (Δ 1.41 ± 0.15 MPa, p = 0.03). With greater correction angle 5°, respectively, 10° peak and contact pressure increased accordingly. In contrast, the biplanar distal osteotomy group showed significant decrease of pressure values (p = 0.004). The extracapsular, extra-articular absorber had no significant influence on pressure levels in the patellofemoral joint. CONCLUSION: HTO with a proximal biplanar osteotomy of the tuberositas tibia significantly increased patellofemoral pressure conditions depending on the correction angle. In contrast a distally directed biplanar osteotomy diminished these effects while implantation of an extracapsular, extra-articular absorber had no influence on the patellofemoral compartment at all. Consequently, patients with varus alignment with additional retropatellar chondropathia should be treated with a distally adverted osteotomy to avoid further undesirable pressure elevation in the patellofemoral joint.

Risk Factors and Predictors of Significant Chondral Surface Change From Primary to Revision Anterior Cruciate Ligament Reconstruction: A MOON and MARS Cohort Study.

BACKGROUND: Articular cartilage health is an important issue following anterior cruciate ligament (ACL) injury and primary ACL reconstruction. Factors present at the time of primary ACL reconstruction may influence the subsequent progression of articular cartilage damage. HYPOTHESIS: Larger meniscus resection at primary ACL reconstruction, increased patient age, and increased body mass index (BMI) are associated with increased odds of worsened articular cartilage damage at the time of revision ACL reconstruction. STUDY DESIGN: Case-control study; Level of evidence, 3. METHODS: Subjects who had primary and revision data in the databases of the Multicenter Orthopaedics Outcomes Network (MOON) and Multicenter ACL Revision Study (MARS) were included. Reviewed data included chondral surface status at the time of primary and revision surgery, meniscus status at the time of primary reconstruction, primary reconstruction graft type, time from primary to revision ACL surgery, as well as demographics and Marx activity score at the time of revision. Significant progression of articular cartilage damage was defined in each compartment according to progression on the modified Outerbridge scale (increase ≥1 grade) or >25% enlargement in any area of damage. Logistic regression identified predictors of significant chondral surface change in each compartment from primary to revision surgery. RESULTS: A total of 134 patients were included, with a median age of 19.5 years at revision surgery. Progression of articular cartilage damage was noted in 34 patients (25.4%) in the lateral compartment, 32 (23.9%) in the medial compartment, and 31 (23.1%) in the patellofemoral compartment. For the lateral compartment, patients who had >33% of the lateral meniscus excised at primary reconstruction had 16.9-times greater odds of progression of articular cartilage injury than those with an intact lateral meniscus ( P < .001). For the medial compartment, patients who had <33% of the medial meniscus excised at the time of the primary reconstruction had 4.8-times greater odds of progression of articular cartilage injury than those with an intact medial meniscus ( P = .02). Odds of significant chondral surface change increased by 5% in the lateral compartment and 6% in the medial compartment for each increased year of age ( P ≤ .02). For the patellofemoral compartment, the use of allograft in primary reconstruction was associated with a 15-fold increased odds of progression of articular cartilage damage relative to a patellar tendon autograft ( P < .001). Each 1-unit increase in BMI at the time of revision surgery was associated with a 10% increase in the odds of progression of articular cartilage damage ( P = .046) in the patellofemoral compartment. CONCLUSION: Excision of the medial and lateral meniscus at primary ACL reconstruction increases the odds of articular cartilage damage in the corresponding compartment at the time of revision ACL reconstruction. Increased age is a risk factor for deterioration of articular cartilage in both tibiofemoral compartments, while increased BMI and the use of allograft for primary ACL reconstruction are associated with an increased risk of progression in the patellofemoral compartment.

Outcomes and complications of unicondylar arthroplasty.

Unicompartmental knee arthroplasty has experienced resurgence in popularity because of the lower morbidity of the procedure and the proposed benefits over total knee replacement in appropriately selected patients. Improved component designs and advanced surgical techniques have promoted excellent results. Expanded indications to include the very young and the elderly have yielded comparable clinical outcomes. Nonetheless, the success of unicompartmental replacement depends on proper surgical technique and patient selection. Distinct surgical considerations exist depending on whether the medial, lateral, or patellofemoral compartment is replaced. Long-term studies have shown that unicompartmental knee replacement is an alternative to total knee arthroplasty.