Running Injuries: The Infrapatellar Fat Pad and Plica Injuries

Total knee arthroplasty: do newer CR implants yield better results? A single center prospective study

The aim of this study was to compare whether the newest TKA prosthesis (Persona) gives improved clinical outcomes due its more anatomical design in comparison to older prostheses (balanSys). This study included a total of 89 patients planned for TKA from June 2018 to September 2019. Outcomes such as Knee Injury and Osteoarthritis Outcome Score (KOOS), range of motion (ROM), numeric pain rating scale (NRS), analgesics and alignment were recorded next to patient characteristics and complications. Our results showed a significant improvement in NRS, ROM and functional scores postoperatively compared to preoperatively for both the Persona and the balanSys implants. Although the flexion ROM for the Persona group was higher at 6 and 12 months postoperative compared to the balanSys, this was mainly a regaining of the preoperative ROM. Throughout all timepoints, there were no statistically significant differences observed in NSAID and opioid usage between the balanSys and Persona groups. Both implants are safe and efficient to use in the treatment of knee osteoarthritis. Although Persona had an improved postoperative flexion, this did not have an impact on any of the patient-reported outcomes.

The Use of Infrapatellar Fat Pad-Derived Mesenchymal Stem Cells in Articular Cartilage Regeneration: A Review

Cartilage is frequently damaged with a limited capacity for repair. Current treatment strategies are insufficient as they form fibrocartilage as opposed to hyaline cartilage, and do not prevent the progression of degenerative changes. There is increasing interest in the use of autologous mesenchymal stem cells (MSC) for tissue regeneration. MSCs that are used to treat articular cartilage defects must not only present a robust cartilaginous production capacity, but they also must not cause morbidity at the harvest site. In addition, they should be easy to isolate from the tissue and expand in culture without terminal differentiation. The source of MSCs is one of the most important factors that may affect treatment. The infrapatellar fat pad (IPFP) acts as an important reservoir for MSC and is located in the anterior compartment of the knee joint in the extra-synovial area. The IPFP is a rich source of MSCs, and in this review, we discuss studies that demonstrate that these cells have shown many advantages over other tissues in terms of ease of isolation, expansion, and chondrogenic differentiation. Future studies in articular cartilage repair strategies and suitable extraction as well as cell culture methods will extend the therapeutical application of IPFP-derived MSCs into additional orthopedic fields, such as osteoarthritis. This review provides the latest research concerning the use of IPFP-derived MSCs in the treatment of articular cartilage damage, providing critical information for the field to grow.

Narrative: Review of Anterior Knee Pain Differential Diagnosis (Other than Patellofemoral Pain)

PURPOSE OF REVIEW

This review presents a framework for constructing a differential diagnosis for chronic anterior knee pain associated with overuse other than patellofemoral pain. Traumatic, systemic, and pediatric injuries will not be covered.

RECENT FINDINGS

From superficial to deep, the anterior knee can be conceptually organized into four layers: (1) soft tissue, (2) extensor mechanism, (3) intracapsular/extrasynovial, and (4) intra-articular. From superficial to deep, diagnoses to consider include bursitis, patellar and quadriceps tendinosis, fat pad impingement, and plica syndromes.

Association Between Self-reported Measures, Physical Examination, and Early Magnetic Resonance Imaging Signs of Osteoarthritis in Patients With Patellofemoral Pain

BACKGROUND

Structural abnormalities associated with osteoarthritis (OA) are found in some patients with patellofemoral pain (PFP).

OBJECTIVES

To investigate the association between early signs of OA on magnetic resonance imaging (MRI) and characteristics from self-reported measures and physical examination in patients with PFP.

METHODS

This exploratory study included data from patients with PFP from a previously published cross-sectional case-control study (n = 64; 55% female; mean ± SD age, 23.4 ± 7.0 years). Structural OA features (osteophytes, bone marrow lesions, cartilage defects, Hoffa synovitis, patellar tendon abnormalities) and quantitative T2 measurements of cartilage composition were extracted from MRI. Associations between characteristics from self-reported measures (pain at rest, pain during stair walking, knee function, duration of complaints, hours of sports participation each week), physical examination (crepitus, quadriceps strength), and early MRI signs of OA were assessed.

RESULTS

Symptom duration was associated with bone marrow lesions in the patella (odds ratio [OR] = 1.1; 95% confidence interval [CI]: 1.0, 1.2). Sports participation (hours per week) was inversely associated with patellar tendon abnormalities on MRI (OR = 0.8; 95% CI: 0.6, 1.0). Crepitus and bilateral nature of the complaints were associated with minor patellar cartilage defects (OR = 12.0; 95% CI: 2.3, 63.6 and OR = 7.6; 95% CI: 1.1, 53.8, respectively). There were no significant associations between clinical characteristics and cartilage T2 relaxation time.

CONCLUSION

Presence of crepitus, bilateral complaints, a long PFP symptom duration, and reduced weekly sport participation were associated with early signs of OA in a young PFP population.

LEVEL OF EVIDENCE

Etiology, level 2c. J Orthop Sports Phys Ther 2019;49(9):634-639. Epub 10 Jul 2019. doi:10.2519/jospt.2019.8889.

How does acute pain influence biomechanics and quadriceps function in individuals with patellofemoral pain?

OBJECTIVES

Beside pathophysiological factors, pain is believed to play a crucial role in the progression of patellofemoral pain (PFP). However, the isolated effect of pain on biomechanics and quadriceps function has not been investigated in PFP. Thus, this study aimed to investigate the effect of pain on quadriceps function and lower limb biomechanics in individuals with PFP.

METHODS

Twenty-one individuals with PFP (11 males and 10 females, age: 29.76 ± 6.36 years, height: 1.74 ± 0.09 m, mass: 70.12 ± 8.56 kg) were measured at two different occasions: when not and when experiencing acute pain. Peak quadriceps torque (concentric, eccentric and isometric) and arthrogenic muscle inhibition (AMI) were assessed. Three-dimensional motion analysis and surface electromyography of the quadriceps and hamstring muscles were collected during running, a single-leg-squat and step-down task. The normality was assessed using the Shapiro-Wilk test and a MANOVA was performed at the 95% confidence interval.

RESULTS

AMI increased significantly in acute pain. The net muscle activation of the knee extensors and flexors decreased during running in acute pain. The lower limb biomechanics and the quadriceps torque did not change in acute pain.

DISCUSSION

It appears that even if individuals with PFP experience pain they can still deliver maximal quadriceps contractions and maintain their moving patterns without biomechanical changes. However, the overall reduced activation of the quadriceps and the increased AMI indicate the presence of quadriceps inhibition in acute pain.

Infrapatellar Fat Pad Stem Cells: From Developmental Biology to Cell Therapy

The ideal cell type to be used for cartilage therapy should possess a proven chondrogenic capacity, not cause donor-site morbidity, and should be readily expandable in culture without losing their phenotype. There are several cell sources being investigated to promote cartilage regeneration: mature articular chondrocytes, chondrocyte progenitors, and various stem cells. Most recently, stem cells isolated from joint tissue, such as chondrogenic stem/progenitors from cartilage itself, synovial fluid, synovial membrane, and infrapatellar fat pad (IFP) have gained great attention due to their increased chondrogenic capacity over the bone marrow and subcutaneous adipose-derived stem cells. In this review, we first describe the IFP anatomy and compare and contrast it with other adipose tissues, with a particular focus on the embryological and developmental aspects of the tissue. We then discuss the recent advances in IFP stem cells for regenerative medicine. We compare their properties with other stem cell types and discuss an ontogeny relationship with other joint cells and their role on in vivo cartilage repair. We conclude with a perspective for future clinical trials using IFP stem cells.