Management of patellar and trochlear cartilage lesions with matrix-induced autologous chondrocyte implantation in conjunction with patellofemoral realignment procedures improves patient-reported outcomes and magnetic resonance image appearance.

OBJECTIVES: The aim of this study is to evaluate the relationship between the achievement of clinically significant improvement in patient-reported outcome measures (PROMs) and the postoperative magnetic resonance image (MRI) appearance of matrix-associated chondrocyte implantation (MACI), in conjunction with patellofemoral realignment procedures, for the treatment of grade-IV chondral defects about the patellofemoral joint. METHODS: A retrospective review of patients undergoing MACI for grade-IV chondral defects of the patella or trochlea by a single sports-medicine-fellowship-trained surgeon from 2017 to 2020 was performed. Concomitant realignment procedures, including tibial tubercle osteotomy and medial patellofemoral ligament reconstruction, were also performed as needed. Patients with preoperative and minimum 1-year postoperative PROMs and postoperative knee MRI were included. MRI scans were obtained at 6.3 (interquartile range: 5.8, 7.5) months postoperatively. A fellowship-trained musculoskeletal radiologist assigned a Magnetic Resonance Observation of Cartilage Repair Tissue (MOCART) score (range: 0-100, with 100 equating to complete graft healing) to each MRI. Achievement of the minimal clinically important difference (MCID) for International Knee Documentation Committee (IKDC), Knee Injury and Osteoarthritis Score-Quality of Life, and Kujala scores were determined for each patient. Paired t-tests or Wilcoxon rank-sum tests were used to evaluate for an association between achievement of the MCID for each PROM and MOCART score. The average follow-up time and time from surgery to PROMs were 2.7 â€‹± â€‹1.5 years and 1.7 â€‹± â€‹0.66 years, respectively. RESULTS: Thirty patients were included. There was a significant improvement in all PROMs from preoperative to postoperative (p â€‹< â€‹0.001). More than two-thirds of patients achieved the MCID for each PROM. Patients who achieved the MCID for IKDC had significantly higher MOCART scores (66.5 â€‹± â€‹16.2) than those who did not meet the MCID for IKDC (50.6 â€‹± â€‹23.6, p â€‹= â€‹0.043). CONCLUSION: MACI for the treatment of patellofemoral chondral injuries is associated with clinically significant improvement in PROMs at short-term follow-up. Clinically significant improvements in IKDC scores are associated with a more mature MRI appearance of the autologous chondrocyte implantation graft on postoperative MRI, as indicated by higher MOCART scores. LEVEL OF EVIDENCE: IV-Case Series.

Editorial Commentary: Both Osteochondral Allograft Transplantation and Autologous Chondrocyte Implantation Are Valuable Treatment Options for Patellofemoral Joint Cartilage Defects.

The patellofemoral (PF) joint is a challenging location to repair cartilage. Although both osteochondral allograft transplantation (OCA) and autologous chondrocyte implantation (ACI) are established as standard therapies for cartilage repair, most treatment algorithms continue to favor ACI for the PF joint, which shows a high rate of success. Today, however, OCA is a treatment of choice to revise prior failed PF cartilage repair. The positive outcomes in this setting encourage indicating OCA for select primary cartilage repair patients, namely those with defects that are uncontained or osteochondral. An advantage of OCA over ACI is that the tissue is more robust and there may be less need for osteotomy to unload the PF joint. Even for ACI, tibial tubercle osteotomy is reserved for patients with abnormal patellar tracking and/or patellar height. In terms of return to sports, realistic expectations are required. Both ACI and OCA are valuable treatment options for PF cartilage defects.

Initial Outcomes of Single versus Multiple-Plug Osteochondral Allograft Transplantation for Osteochondral Defects of the Knee: A Matched Cohort Analysis.

Although several prior studies have described the outcomes of osteochondral allograft (OCA) transplantation for single osteochondral lesions, there is a paucity of comparative data on outcomes of single versus multiple OCA transplants. We aimed to describe the initial outcomes of single-plug versus multiple-plug knee OCA transplants at a minimum of 1 year of follow-up. We hypothesized that there would be no difference in patient-reported outcome measures (PROMs) between patients undergoing single-plug and multiple-plug OCA transplants at a minimum of 1 year of follow-up. We retrospectively reviewed the prospectively collected data of patients undergoing OCA transplantation for large (>2 cm2) osteochondral defects of the knee. Thirty patients who underwent multiple-plug (2 + ) OCA transplants (either single surface using the snowman technique or multi-surface) were 1:1 age, sex, and body mass index (BMI) matched with 30 patients who underwent single-plug OCA transplants. PROMs, including the International Knee Documentation Committee (IKDC) and Knee Injury and Osteoarthritis Outcome Score (KOOS) subscores, were obtained both preoperatively and at a minimum of 1 year postoperatively. Failure was defined as a revision OCA or conversion to unicompartmental knee arthroplasty (UKA) or total knee arthroplasty (TKA). The cohort comprised 30 females (31 affected left knees), with an average age of 37 ± 10.3 years and median follow-up of 2.0 years (interquartile range: 1.7-2.5 years). There was a significant increase in PROMs from the preoperative to the postoperative period for the entire cohort and the single-plug versus multiple-plug subgroups (p < 0.01). There was no difference between the groups with respect to the percentage of patients who achieved the minimal clinically important difference (MCID) for each PROM (p > 0.05). There were two failures, both in the single-plug group, with a mean time to failure of 3.5 years. There was no difference in the initial outcomes between patients undergoing single-plug versus multiple-plug OCA transplant at the short-term follow-up. LEVEL OF EVIDENCE:: Level IV, case series.

Risk Factors for Atraumatic Medial Patellar Facet Lesions.

Background: Medial patellar facet lesions have been well-described in the setting of patellar instability. However, relatively little is known about risk factors for atraumatic medial patellar facet lesions. Purpose/Hypothesis: To identify clinical and radiographic risk factors for medial patellar facet lesions in patients without a history of trauma or patellar instability. It was hypothesized that a posterior tibial tubercle relative to the trochlear groove would be a risk factor for atraumatic medial patellar facet lesions. Study Design: Case-control study; Level of evidence, 3. Methods: A total of 37 patients with atraumatic medial patellar facet lesions were matched by age, sex, and body mass index with 37 control patients without a history of patellofemoral dysplasia. Demographic and imaging characteristics were compared between groups. Plain radiography was used to evaluate Wiberg type, and magnetic resonance imaging was used to calculate Caton-Deschamps index, tibial tubercle-trochlear groove distance, trochlear facet asymmetry ratio, patellotrochlear index, sulcus depth, patellar bisect ratio, and tibial tubercle height. Statistically significant variables from univariate analysis were used as inputs to the multivariate regression model to assess independent risk factors. Results: There were no differences between groups with respect to Wiberg type, Caton-Deschamps index, tibial tubercle-trochlear groove distance, sulcus depth, or patellotrochlear index (P > .05 for all). The medial facet lesion group had a larger medial trochlear facet (trochlear facet asymmetry ratio, 0.72 ± 0.11 vs 0.60 ± 0.09; P < .001), a more medial-lying patella in the trochlear groove (patellar bisect ratio, 0.57 ± 0.06 vs 0.55 ± 0.07; P = .035), and a more posterior tibial tubercle relative to the trochlear groove (tibial tubercle height, -3.13 ± 5.21 vs -0.23 ± 5.93 mm; P = .030) compared with the control group. Multivariate regression analysis identified trochlear facet asymmetry and tibial tubercle height as independent risk factors for medial patellar facet lesions (relative risk = 97.3 [95% CI, 14.9-635.1], P < .001 and relative risk = 0.95 [95% CI, 0.92-0.98], P = .004, respectively). Conclusion: A relatively larger medial trochlear facet and a more posterior tibial tubercle relative to the trochlear groove were found to be risk factors for medial patellar facet lesions in patients without a history of trauma or patellar instability.

Decreased Effective Patellar Tendon Length following Distalization Tibial Tubercle Osteotomy without Patellar Tendon Tenodesis.

Background: Distalization tibial tubercle osteotomy (TTO) is an effective treatment for improving patellar height in patients with patella alta associated with patellofemoral instability and cartilage lesions. The addition of a patellar tendon tenodesis has been suggested; nonetheless, concerns exist regarding possible increased patellofemoral cartilage stresses. Purpose: To evaluate pre- and postoperative patellar tendon length and alignment parameters on magnetic resonance imaging (MRI), as well as patient-reported outcome measures (PROMs) after distalization TTO without patellar tendon tenodesis. Study Design: Case series; Level of evidence, 4. Methods: Twenty skeletally mature patients who underwent distalization TTO with or without anteromedialization at our institution between December 2014 and August 2021 were included. All patients underwent pre- and postoperative MRIs of the affected knee. The Caton-Deschamps index (CDI), the axial and sagittal tibial tubercle-trochlear groove (TT-TG) distances, the distances from the tibial plateau to the patellar tendon insertion and the tibial tubercle, and the patellar tendon length were assessed. PROMs included the International Knee Documentation Committee Subjective Knee Evaluation Form, the Knee injury and Osteoarthritis Outcome Score-Quality of Life subscale, the Kujala Anterior Knee Pain Scale, and the Veterans RAND 12-Item Health Survey mental and physical component scores. Results: The mean patient age at surgery was 27.4 years (range, 14-42 years). Radiographic parameters demonstrated improved patellar height (CDI decreased from 1.36 to 1.11; P < .001) after distalization TTO. The distance from the tibial plateau to the patellar tendon insertion significantly decreased from 20.1 mm preoperatively to 17.9 mm postoperatively (P < .020), and the patellar tendon length decreased from 53.4 mm preoperatively to 46.0 mm postoperatively (P < .001). The patellar tendon insertion was not distalized after distalization TTO, likely because of scarring of the patellar tendon proximal to the osteotomy site. Patients demonstrated significant pre- to postoperative improvements on all PROMs (P≤ .024 for all ). There were 4 (20%) complications-2 cases of arthrofibrosis, 1 postoperative infection, and 1 osteotomy delayed union. Conclusion: Distalization TTO without patellar tendon tenodesis was associated with improved radiographic outcomes and PROMs. It provides an additional tool for surgical management of patellofemoral pathology with associated patella alta.

Increased Host Bone Marrow Edema on 6-Month Magnetic Resonance Imaging Is a Risk Factor for Osteochondral Allograft Failure.

PURPOSE: To evaluate the presence of host bone marrow edema (BME) surrounding osteochondral allograft (OCA) plugs on routine 6-month postoperative magnetic resonance imaging (MRI) and to determine whether such BME is correlated with subsequent failure. METHODS: The present study was approved under our institutional review board-approved database (#2020-2123). We included patients who underwent cartilage repair with OCA for focal chondral and osteochondral defects of the distal femur by 2 senior surgeons between January 2016 and May 2021 with minimum 2-year follow-up. OCA is frequently performed with concomitant procedures, and therefore ligament reconstruction, meniscal surgery, and osteotomy were not exclusion criteria. Failure was defined as (1) poor clinical outcome with graft collapse on follow-up MRI or second-look arthroscopy, (2) primary OCA removal or revision, or (3) conversion to unicompartmental or total knee arthroplasty. Routine MRI scans were performed at 6 ± 2 months postoperatively. All postoperative MRI scans were reviewed from our imaging record by 2 blinded fellowship-trained orthopaedic surgeons. Patients were divided for analyses into 2 groups: BME ≥10 cm3 versus BME <10 cm3. RESULTS: Of the 85 patients eligible for the study, 56 patients (30 female, mean age 31.69 ± 11.34 years) had a minimum 2-year follow-up. Nonfailure cases had a mean clinical follow-up of 3.13 ± 0.93 years. The mean time from surgery to failure in our cohort was 1.67 ± 0.91 years. There were 12 (21.4%) patients with BME ≥10 cm³ and 44 (78.6%) patients with BME <10 cm³. No statistically significant differences were found between groups when compared for sex, age, body mass index, OCA size, time to MRI, mean follow-up, number of plugs, graft location, diagnosis, previous surgeries, or concomitant procedures. All OCA failures of the study cohort were in the BME ≥10 cm³ group, representing 50% of this group (P < .001). Kaplan-Meier survival analysis with the log-rank test demonstrated significant difference in survival distributions between groups (P < .001). Patients who ultimately failed had a mean BME volume of 18.49 ± 5.82 cm3, while the nonfailure group had a mean volume of 4.66 ± 4.97 cm3 (P < .001). Cutoff values around 10 cm³ in receiver operating characteristic curve analysis demonstrated 100% sensitivity and close to 90% specificity for OCA failure diagnosis. CONCLUSIONS: Host BME with a volume greater than 10 cm³ on 6-month postoperative MRI is predictive of an increased subsequent failure rate after OCA transplantation with a failure rate of 50%. LEVEL OF EVIDENCE: Level III, cohort study.

Impact of Wiberg Patellar Type on Outcomes and Survival Following Cell-Based Cartilage Repair for Patellar Chondral Lesions at Midterm Follow-up.

BACKGROUND: Cell-based cartilage repair procedures of the patellofemoral joint have less reliable outcomes than those of the tibiofemoral joint. No previous studies have evaluated the influence of patellar shape on cell-based cartilage repair outcomes. Patellar dysplasia may predispose patients to worse outcomes after cell-based cartilage repair. PURPOSE/HYPOTHESIS: The purpose of this study was to evaluate the relationship between Wiberg patellar type and outcomes after cell-based cartilage repair (autologous chondrocyte implantation or particulated juvenile allograft cartilage transplantation) for the treatment of patellar chondral lesions at a minimum 2-year follow-up. It was hypothesized that Wiberg classification of patellar shape would have no effect on patient-reported outcome measures (PROMs) or graft survival. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: Patients undergoing autologous chondrocyte implantation or particulated juvenile allograft cartilage transplantation for full-thickness patellar chondral defects between 2016 and 2020 were retrospectively reviewed after institutional review board approval. The change in PROMs, including International Knee Documentation Committee (IKDC), Kujala, and Veterans RAND 12-item Health Survey Mental and Physical scores, from pre- to postoperatively and the percentage of patients who achieved the minimal clinically important difference (MCID) for IKDC and Kujala scores were compared for the Wiberg type A versus Wiberg type B versus Wiberg type C groups. The log-rank test was used to evaluate for differences in survival between subgroups. RESULTS: A total of 59 patients (63 knees) were included, with a mean age of 33.3 ± 8.6 years, median body mass index of 26.0 (IQR, 21.8-30.2), and median follow-up time of 3.5 years (IQR, 2.6-4.2 years). In total, 26 (41%) patellae were Wiberg type A, 29 (46%) were Wiberg type B, and 8 (13%) were Wiberg type C. There were no differences between Wiberg type A versus Wiberg type B versus Wiberg type C groups with respect to change in PROMs from pre- to postoperatively or the percentage of patients who achieved the MCID for IKDC or Kujala scores (P > .05 for all). There were no differences in survival between groups (P = .45). CONCLUSION: Wiberg patellar type has no effect on patient-reported outcomes or graft survival at midterm follow-up. Patellar dysplasia should not be seen as a contraindication for cell-based cartilage repair procedures.

Short-Term Outcomes of Concomitant Patellofemoral Arthroplasty and Medial Patellofemoral Ligament Reconstruction to Treat Concurrent Patellofemoral Arthritis and Patellar Instability.

The purpose of this study was to evaluate the efficacy of combined patellofemoral arthroplasty (PFA) and medial patellofemoral ligament (MPFL) reconstruction in patients with patellofemoral arthritis in the setting of concomitant patellar instability. Patients who underwent single-stage, combined PFA and MPFL reconstruction by a single surgeon at a tertiary-care orthopaedic center between 2016 and 2021 were identified. Postoperative radiographic and clinical outcomes at a minimum of 6 months were recorded using patient-reported outcome measures, including International Knee Documentation Committee (IKDC), Kujala, and VR-12. Early complications and rates of recurrent instability were also recorded. Of the 16 patients who met inclusion and exclusion criteria, 13 patients were available for final follow-up (81%; 51.7 ± 7.2 years, 11 females, 2 males) with a mean clinical follow-up of 1.3 ± 0.5 years (range: 0.5-2.3 years). Patients experienced significant improvements in patellar tilt and multiple patient-reported outcome metrics postoperatively, including IKDC, Kujala, VR-12 Mental Health, and VR-12 Physical Health. At the time of the most recent follow-up, no patient had experienced a postoperative dislocation or subluxation event. The findings suggest that concurrent PFA and MPFL reconstruction are associated with significant improvements in multiple patient-reported outcomes. Further studies are needed to evaluate the duration of clinical benefits achieved with this combined intervention.

Measure Twice, Cut Once: The Future of Digitally Planned Knee Osteotomies.

It is important to highlight the use of patient-specific cutting guides for knee joint osteotomies. Rationale, pitfalls, and planning of conventional osteotomy techniques are examined. The benefits of using patient-specific guides focusing on the potential for improved accuracy, efficiency, and safety are reviewed. The versatility of guides to manipulate the slope in both the coronal and sagittal planes, as well as its ability to accommodate concomitant procedures, is discussed. The time and cost differentials between standard cutting guides and three-dimensional-guided templating are also discussed.

Predilection of Patellofemoral Cartilage Lesions in Patients with Posterior Medial Meniscal Root Lesions.

OBJECTIVE: The present study aims to compare the presence and severity of patellofemoral osteoarthritis between patients with root lesions and non-root lesions. DESIGN: A total of 102 patients were included in this study (51 root lesions and 51 non-root lesions). The root lesion cohort was matched to a non-root lesion cohort based on sex, body mass index, and age at the time of surgery. Radiographic evaluation with modified Outerbridge scoring of MRI of the knee was performed to determine the severity of degeneration of the knee joint preoperatively. Mann-Whitney and Independent t tests were used to compare the groups. RESULTS: The root lesion group had statistically greater Outerbridge patella scores (M = 2.45 ± 1.12) and trochlear scores (M = 2.27 ± 1.37) than the non-root lesion patients (M = 1.78 ± 1.30, P = 0.006, and M = 1.55 ± 1.40, P = 0.010, respectively). When using a new scale for grading patellofemoral arthritis, the root lesion group had statistically greater scores (M = 8.33 ± 3.38) than the non-root lesion patients (M = 5.67 ± 3.07) (P < 0.001). CONCLUSION: Patients with root lesions have a greater degree of patellofemoral cartilage lesions than patients without root lesions. The presence of cartilage lesions preoperatively in root lesion patients has presented the question of whether repair is worthwhile or if one should delay surgery until arthroplasty is indicated. Future research should be carried out on outcomes of root repair surgery in patients with patellofemoral cartilage lesions, in addition to considering the patient's age, activity level, and other risk factors.

Proximal bone block with distal screw trajectory improves mechanical stability during distalization tibial tubercle osteotomy.

PURPOSE: The purpose of this study was to quantify differences in mechanical stability of a wedge-shaped distalization tibial tubercle osteotomy (TTO) with a standard technique, versus a modified technique with use of a proximal bone block and distally angled screw trajectory. METHODS: Ten fresh-frozen cadaver lower extremity specimens (five matched pairs) were utilized. Within each specimen pair, one specimen was randomly assigned to undergo a standard distalization osteotomy fixed with two bicortical 4.5-mm screws oriented perpendicular to the long axis of the tibia, and the other to undergo a distalization osteotomy with modified fixation utilizing a proximal bone block and distally angled screw trajectory. Each specimen's patella and tibia were mounted on a servo-hydraulic load frame using custom fixtures (MTS Instron). The patellar tendon was dynamically loaded to 400 N at a rate of 200 N/second for 500 cycles. Following the cyclic loading, loading to failure was done at 25 mm/min. RESULTS: The modified distalization TTO technique demonstrated significantly higher average load to failure compared to the standard distalization TTO technique (1339 N vs. 844.1 N, p < 0.001). Average maximum tibial tubercle displacement during cyclic loading was significantly smaller in the modified TTO technique group compared to the standard TTO technique (1.1 mm vs. 4.7 mm, p < 0.001). CONCLUSION: This study demonstrates that distalization TTO utilizing a modified technique with a proximal bone block and distally aimed screws is biomechanically superior to standard distalization TTO without proximal bone block and screw trajectory perpendicular to the long axis of the tibia. This increased stability may aid in reducing the reported higher complication rates (including loss of fixation, delayed union and nonunion) following distalization TTO, although future clinical outcome studies are warranted.

Establishing minimal detectable change thresholds for the international knee documentation committee and Kujala scores at one and two years after patellofemoral joint arthroplasty.

PURPOSE: To define the minimal detectable change (MDC) for the international knee documentation committee (IKDC) and Kujala scores one and two years after patellofemoral joint arthroplasty (PFA). METHODS: A distribution-based method (one-half the standard deviation of the mean difference between postoperative and preoperative outcome scores) was applied to establish MDC thresholds among 225 patients undergoing primary PFA at a single high-volume musculoskeletal-care center. Stability of change in MDC achievement was explored by quantifying the proportion of achievement at one- and two-year postoperative timepoints. Multivariable logistic regression analysis was performed to explore the association between sociodemographic and operative features on MDC achievement. RESULTS: MDC thresholds for the Kujala score were 10.3 (71.1% achievement) and 10.6 (70.4% achievement) at one- and two years, respectively. The MDC thresholds for the IKDC score were 11.2 (78.1% achievement) and 12.3 (69.0% achievement) at one- and two years, respectively. Predictors of achieving the MDC for the Kujala and IKDC scores at both time points were lower preoperative Kujala and IKDC scores, respectively. Preoperative thresholds of ≤ 24.1 and 7.6 for the Kujala and IKDC scores, respectively, were associated with a 90% MDC achievement probability. When preoperative thresholds approached 64.3 and 48.3 for the Kujala and IKDC, respectively, MDC achievement probability reduced to 50%. CONCLUSION: The MDC thresholds for the Kujala and IKDC scores two years after PFA were 10.6 and 12.3, respectively. Clinically significant health status changes were maintained overall, with a slight decrease in achievement rates between one and two years. MDC achievement was associated with disability at presentation, and several probability-based preoperative thresholds were defined. These findings may assist knee surgeons with patient selection and the decision to proceed with PFA by better understanding the patient-specific propensity for MDC achievement. LEVEL OF EVIDENCE: IV, retrospective case series.

An implantable shock absorber yields an 85% survival-from-arthroplasty rate through 5 years in working-age patients with medial compartment knee osteoarthritis.

PURPOSE: To evaluate the 5-year rate of survival without undergoing arthroplasty or high tibial osteotomy (HTO) in subjects with mild-to-moderate medial compartment knee osteoarthritis (OA) who were treated with an implantable shock absorber (ISA) system. METHODS: Three prospective, sequential, multicenter, international, single-arm clinical trials were conducted comprising subjects who received an ISA for symptomatic medial knee OA after failing ≥ 6 months of conservative therapy. Study outcomes were analyzed cumulatively and by enrollment group when all subjects' follow-up data exceeded the 2-year threshold after ISA implantation. Primary outcome was survival rate without conversion to arthroplasty/HTO. Secondary outcomes were changes in Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain and function scores after ISA implantation. RESULTS: All 171 enrolled subjects (age 51 ± 9 years, body-mass index 28.5 ± 3.5 kg/m2, 38% female; study knee Kellgren-Lawrence score 2.7 ± 0.9 points) were followed for a minimum of 2, and up to 5, years after device implantation. Overall, 90.6% (155/171) of subjects survived without requiring arthroplasty/HTO at last follow-up (mean 3.2 ± 1.6 years). The Kaplan-Meyer median 3- and 5-year survival-without-arthroplasty point estimates were 89.8% (95% CI 86.5‒95.7%) and 84.9% (95% CI 75.1‒91.1%), respectively. The median 3-year estimated survival rate for the most recent study (n = 81) was 97.3%. The mean WOMAC Pain score decreased 71% from baseline to last follow-up after ISA implantation, from 58 ± 13 to 16 ± 17 points (p < 0.0001). The Function score improved 69%, decreasing from 56 ± 18 to 17 ± 17 points (p < 0.0001). CONCLUSIONS: In younger patients with mild-to-moderate symptomatic medial compartment knee OA, implantation of the ISA device resulted in a 5-year survival rate of 85% from undergoing arthroplasty or HTO. The ISA system may be an effective treatment option for working-age patients with medial knee OA who are not candidates for or do not desire more invasive surgical approaches. LEVEL OF EVIDENCE: II.

Anteromedialization Tibial Tubercle Osteotomy Improves Patellar Contact Forces: A Cadaveric Model of Patellofemoral Dysplasia.

BACKGROUND: Patellofemoral (PF) dysplasia is common in patients with recurrent patellar instability. Tibial tubercle osteotomy (TTO) is performed with goals of correcting patellar maltracking and redistributing contact forces across the PF joint. The biomechanical effects of TTO in the setting of PF dysplasia have not been quantified. PURPOSE/HYPOTHESIS: To quantify patellar contact mechanics and kinematics after TTO in the setting of PF dysplasia. We hypothesized that a simulated anteromedialization (AMZ) TTO would improve PF contact mechanics as compared with a pure medialization TTO. STUDY DESIGN: Controlled laboratory study. METHODS: PF dysplasia with Dejour type D classification was simulated in 7 cadaveric knees by replacing the native patellar and trochlear surfaces with synthetic polymeric patellar and trochlear implants. On each specimen, a flat TTO was fixed in 3 distinct positions simulating a pathologic lateralized tubercle (pathologic condition), a medialized tubercle (Elmslie Trillat), and an AMZ tubercle. The sum of forces acting on the medial and lateral patellar facet and patellar kinematics was computed for each knee for each condition from 0° to 70° of flexion at 10° increments. RESULTS: Relative to the pathologic condition, AMZ TTO decreased contact forces across the lateral facet (20°-50° and 70° of flexion). Relative to the pathologic condition, Elmslie Trillat TTO had no effect on contact forces on either compartment. Relative to the Elmslie Trillat TTO, the AMZ TTO had significantly decreased contact forces across the medial facet (at 40°, 60°, and 70° of flexion). No significant differences in joint kinematics occurred across any groups. CONCLUSION: Of all groups studied, AMZ TTO resulted in significantly decreased patellar contact forces in simulated dysplastic PF joints. AMZ may be considered in certain patients with PF dysplasia to avoid medial compartment PF chondral overload. CLINICAL RELEVANCE: PF dysplasia is common in patients with recurrent patellar instability who warrant surgical intervention to prevent subsequent recurrence. Numerous interventions to treat this condition, including various TTOs, have been proposed without a clear consensus. This cadaveric biomechanical study demonstrates that AMZ TTO resulted in more favorable PF contact mechanics than Elmslie Trillat TTO in a model representing PF dysplasia. AMZ TTO may be considered for patients in the setting of recurrent instability with PF dysplasia to avoid cartilage overload on the medial compartment of the PF joint.

An Initial Injection and a Crossover Injection of Amniotic Suspension Allograft Following Failed Treatment with Hyaluronic Acid or Saline Are Equally Effective in the Treatment of Moderate Symptomatic Knee Osteoarthritis Over 12 Months.

PURPOSE: The purpose of this crossover study was to determine the efficacy of amniotic suspension allograft (ASA) for moderate symptomatic knee osteoarthritis following failed treatment with hyaluronic acid (HA) or saline through 12 months' postcrossover injection using patient-reported and safety outcomes. METHODS: In this multicenter study, 95 patients from a 200-patient single-blind randomized controlled trial were eligible to crossover and receive a single injection of ASA 3 months after failed treatment with HA or saline. Patient-reported outcomes, including Knee Injury and Osteoarthritis Outcome Score (KOOS) and visual analog scale (VAS), were collected out to 12 months postcrossover to determine pain and function. Radiographs and blood were collected for assessment of changes. Statistical analyses were performed using mixed effects model for repeated measures. RESULTS: Treatment with ASA following failed treatment with HA or saline resulted in significant improvements in KOOS and VAS scores compared with crossover baseline. There were no differences in radiographic measures or anti-human leukocyte antigen serum levels compared with baseline and no severe adverse events reported. In addition, more than 55% of patients were responders at months 3, 6, and 12 as measured by the Outcome Measures in Arthritis Clinical Trials-Osteoarthritis Research Society International simplified responder criteria. There were no significant differences between the original ASA randomized group and crossover cohorts at any of the time points evaluated, suggesting that prior failed treatment with HA or saline did not significantly impact outcomes following treatment with ASA. CONCLUSIONS: This study showed that patients who previously failed treatment with HA or saline had statistically significant improvements in pain and function scores following a crossover injection of ASA that was sustained for 12 months, as measured by KOOS and VAS. There were no serious adverse events reported, and the injection was safe. LEVEL OF EVIDENCE: II, prospective cohort study.

Cost Effectiveness of Allogeneic Umbilical Cord Blood-Derived Mesenchymal Stem Cells in Patients with Knee Osteoarthritis.

OBJECTIVES: The aim of this study was to assess the cost effectiveness of allogeneic umbilical cord blood-derived mesenchymal stem cells with sodium hyaluronate (hUCB-MSC) compared with microfracture in patients with knee cartilage defects caused by osteoarthritis (OA) in South Korea. METHODS: A partitioned survival model approach was taken consisting of five mutually exclusive health states: excellent, good, fair, poor, and death over a 20-year time horizon. Utility values were obtained from a randomized clinical trial. Cost data were extracted from a database provided by the Health Insurance Review & Assessment Service, and the utilization of healthcare services was estimated from an expert panel of orthopedic surgeons using a structured questionnaire. The incremental cost-effectiveness ratio (ICER) in terms of quality-adjusted life-years (QALY) was calculated. Deterministic and probabilistic sensitivity analyses were performed. RESULTS: In the base case, the incremental costs of US$14,410 for hUCB-MSC therapy along with its associated QALY gain of 0.857 resulted in an ICER of US$16,812 (₩18,790,773) per QALY (95% confidence interval [CI] US$13,408-US$20,828) when compared with microfracture treatment from a healthcare payer perspective. From a societal perspective, the ICER was US$268 (₩299,255) per QALY (95% CI -US$2915 to US$3784). When using a willingness-to-pay threshold of US$22,367/QALY, the probability of hUCB being cost effectiveness compared with microfracture was 99% from the healthcare payer perspective and 100% from the societal perspective. CONCLUSIONS: The study demonstrated that hUCB-MSC therapy was cost effective compared with microfracture when treating patients with knee OA. These findings should inform health policy decision makers about considerations for cost-effective therapy for treating knee OA to ultimately enhance population health.

Amniotic suspension allograft improves pain and function in a rat meniscal tear-induced osteoarthritis model.

BACKGROUND: Osteoarthritis is a degenerative disease of the knee that affects 250 million people worldwide. Due to the rising incidence of knee replacement and revision surgery, there is a need for a nonsurgical treatment to reduce pain and improve function in patients with knee osteoarthritis. Placental-derived allografts, such as an amniotic suspension allograft (ASA), provide growth factors and cytokines that could potentially modulate the inflammatory environment of osteoarthritis. The purpose of this study was to evaluate the efficacy of ASA in a rat medial meniscal tear (MMT) induced osteoarthritis model through histology, microCT, synovial fluid biomarkers, and behavioral testing. METHODS: Rats underwent MMT surgery at day - 7; at day 0, rats were injected with either ASA, vehicle control, or fibroblast growth factor-18 (FGF18). Behavioral testing, including gait analysis, pain threshold, incapacitance, and knee swelling were evaluated in-life, along with histology, microCT analysis of cartilage, and synovial fluid testing post-sacrifice. One MMT cohort was sacrificed at day 10, the other at day 21. A third cohort acted as a safety arm and did not receive MMT surgery; these rats were injected with either vehicle control or ASA and evaluated at day 3 and day 21. RESULTS: Behavioral testing showed a significant improvement in pain threshold, incapacitance, and gait following an injection of ASA. MicroCT showed significant improvements in cartilage thickness and attenuation at day 10 only, and histology showed no detrimental effects compared to the vehicle control at day 21. Synovial fluid analysis showed a significant increase in anti-inflammatory IL-10. The safety cohort showed no significant differences except for an increase in synovitis at day 21, which could be evidence of a xenogeneic response in this model. CONCLUSIONS: In this study, an injection of ASA was well tolerated with no adverse events. Improvements in pain and function, along with cartilage properties at day 10, were observed. Increases in anti-inflammatory cytokines was also seen, along with no significant cartilage degeneration at day 21 compared to the vehicle control. This study provides evidence for the use of ASA as a nonsurgical treatment for knee OA.

Treatment of post-meniscectomy knee symptoms with medial meniscus replacement results in greater pain reduction and functional improvement than non-surgical care.

PURPOSE: Partial meniscectomy is a common orthopedic procedure intended to improve knee pain and function in patients with irreparable meniscal tears. However, 6-25% of partial meniscectomy patients experience persistent knee pain after surgery. In this randomized controlled trial (RCT) involving subjects with knee pain following partial meniscectomy, it was hypothesized that treatment with a synthetic medial meniscus replacement (MMR) implant provides significantly greater improvements in knee pain and function compared to non-surgical care alone. METHODS: In this prospective, multicenter RCT, subjects with persistent knee pain following one or more previous partial meniscectomies were randomized to receive either MMR or non-surgical care. This analysis evaluated the 1-year outcomes of this 2-year clinical trial. Patient-reported knee pain, function, and quality of life were measured using nine separate patient-reported outcomes. The primary outcomes were the pain subscale of the Knee injury and Osteoarthritis Outcome Score (KOOS) and the average of all five KOOS subscales (KOOS Overall). Treatment cessation was defined as permanent device removal in the MMR group and any surgical procedure to the index knee in the non-surgical care group. RESULTS: Treated subjects had a median age of 52 years old (range 30-69 years) and one or more previous partial meniscectomies at a median of 34 months (range 5-430 months) before trial entry. Among 127 subjects treated with either MMR (n = 61) or non-surgical care (n = 66), 11 withdrew from the trial or were lost to follow-up (MMR, n = 0; non-surgical care, n = 11). The magnitude of improvement from baseline to 1 year was significantly greater in subjects who received MMR in both primary outcomes of KOOS Pain (P = 0.013) and KOOS Overall (P = 0.027). Treatment cessation was reported in 14.5% of non-surgical care subjects and only 4.9% of MMR subjects (n.s.). CONCLUSION: Treatment with the synthetic MMR implant resulted in significantly greater improvements in knee pain, function, and quality of life at 1 year of follow-up compared to treatment with non-surgical care alone. LEVEL OF EVIDENCE: I.

Patellofemoral joint cartilage restoration with particulated juvenile allograft in patients under 21 years old.

BACKGROUND: Patellofemoral joint cartilage defects are difficult to treat due to their unique thickness and topography. PURPOSE: To report the postoperative outcomes of patients age 21 and younger treated with particulated juvenile allograft cartilage (PJAC) for full-thickness cartilaginous defects of the patellofemoral joint. The primary aim was to report surgical outcomes and complication rates, as well as return to sport activity. A secondary aim was to provide objective scores of defect restoration by magnetic resonance imaging (MRI) assessment. METHODS: A retrospective review of all PJAC cases conducted between 2012 and 2019 at a single tertiary care urban musculoskeletal institution was conducted. Patients 21 years old or younger with minimum clinical follow up of 1 year and postoperative MRI at a minimum of 6 months were included. Cartilage restoration by MRI was independently assessed using the International Cartilage Repair Society's (ICRS) standardized system. RESULTS: Thirty four patients, 36 knees, were included, with mean age 16.1 ± 3.1 years old. Return to sport rate among patients who participated in a sport preoperatively was 100%. On independent MRI assessment, two thirds of defects achieved an overall grade of normal or nearly normal, while 28 patients (78%) had majority defect fill. Primary graft failure occurred in two cases and one patient experienced a surgical complication. CONCLUSION: Restoration of patellofemoral chondral defects in young patients with particulated juvenile allograft results in satisfactory short-term outcomes and postoperative MRI appearance, along with high rates of return to sport and low rate of complications and graft failure. What is known about the subject: Patellofemoral joint cartilage defects are difficult to treat due to their unique thickness and topography. Several cartilage restoration techniques are available, but these rarely achieve the same mechanical properties as native hyaline cartilage. PJAC is a cell-based technique that has demonstrated promise since its introduction in 2007. WHAT THIS STUDY ADDS TO EXISTING KNOWLEDGE: This series of patients adds the largest single cohort of pediatric and adolescent patients who receive PJAC for defects of the patellofemoral joint. Surgeons treating patients in this age group should be aware of every technique, and their respective outcomes.

Management of Chondral Defects Associated with Patella Instability.

Cartilage defects of the patellofemoral joint are commonly found in association with patellar instability owing to abnormal biomechanics. Strategies to address chondral defects of the patellofemoral joint secondary to instability should first address causes of recurrent instability. Most patellofemoral chondral defects associated with instability are less than 2 cm2 and do not generally require intervention beyond chondroplasty. Larger defects of the patella and/or the trochlea can be repaired with osteochondral or surface cartilage repair.