Background and aimsPrevious systematic reviews have reported manifestations of pain sensitisation as a feature of painful knee disorders, in particular osteoarthritis, with moderate evidence for pain sensitisation in patellofemoral pain (PFP). However, despite past studies recruiting female mostly adolescent PFP patients, it is unclear if sex or age plays a role. Investigation is required to determine if altered pain processing is a key feature of PFP and if a subgroup of patients is at an increased risk to help provide targeted management. The primary aim of this systematic review was to examine evidence investigating pain processing in PFP. Secondary aims were to evaluate the relationship between pain processing and (1) sex, (2) age and (3) symptom duration.MethodsThe protocol was prospectively registered with PROSPERO (CRD42019129851). PubMed, CINAHL, Web of Science and EMBASE were systematically searched from inception to April 2019 for studies investigating pain processing in PFP patients compared to controls using quantitative sensory testing. Each included paper was assessed for methodological quality using a modified version of Downs and Black. Means and standard deviations were extracted to calculate standardised mean differences (SMD) and 95% confidence intervals (95% CI). Where possible meta-analysis and meta-regression were performed using a random effects model.ResultsEleven studies were identified, two medium and nine high quality. Meta-analysis indicates moderate evidence for decreased pressure pain thresholds (SMD −0.68, 95% CI −0.93 to −0.43), increased tactile detection thresholds (SMD 1.35, 95% CI 0.49–2.22) and increased warmth detection thresholds (SMD 0.61, 95% CI 0.30–0.92) in PFP patients compared to controls. Secondary analysis indicates moderate evidence for decreased pressure pain thresholds in female compared to male patients (SMD −0.75, 95% CI −1.34 to −0.16). Meta-regression indicates a moderate correlation between decreasing local and distal pressure pain thresholds and decreasing patient age (local R2 = 0.556, p = 0.0211; distal R2 = 0.491, p = 0.0354) but no correlation with symptom duration (p > 0.05).ConclusionsEvidence from this systematic review with meta-analysis and meta-regression appears to suggest the presence of altered pain processing and sensitisation in patients with PFP with increased sensitivity indicated in female patients and younger patients.ImplicationsWith evidence of altered pain processing and sensitisation in PFP, it may be beneficial for clinicians to consider management approaches that aim specifically at adressing neuropathic pain, for example neuroscience education, to improve patients outcomes. With female patients and younger patients indicated as experiencing greater degree of sensitivity, this may be a good demographic to start screening for sensitisation, in order to better identify and treat those most affected.

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OBJECTIVE: To determine the effects of nonsurgical treatments on pain and function in people with patellofemoral pain (PFP). DESIGN: Systematic review with meta-analysis. LITERATURE SEARCH: We searched MEDLINE, Web of Science, and Scopus databases from their inception until May 2022 for interventional randomized controlled trials (RCTs) in people with PFP. STUDY SELECTION CRITERIA: We included RCTs that were scored ≥7 on the PEDro scale. DATA SYNTHESIS: We extracted homogenous pain and function data at short- (≤3 months), medium- (>3 to ≤12 months) and long-term (>12 months) follow-up. Interventions demonstrated primary efficacy if outcomes were superior to sham, placebo, or wait-and-see control. Interventions demonstrated secondary efficacy if outcomes were superior to an intervention with primary efficacy. RESULTS: We included 65 RCTs. Four interventions demonstrated short-term primary efficacy: knee-targeted exercise therapy for pain (standardized mean difference [SMD], 1.16; 95% CI: 0.66, 1.66) and function (SMD, 1.19; 95% CI: 0.51, 1.88), combined interventions for pain (SMD, 0.79; 95% CI: 0.26, 1.29) and function (SMD, 0.98; 95% CI: 0.47, 1.49), foot orthoses for global rating of change (OR = 4.31; 95% CI: 1.48, 12.56), and lower-quadrant manual therapy for function (SMD, 2.30; 95% CI: 1.60, 3.00). Two interventions demonstrated short-term secondary efficacy compared to knee-targeted exercise therapy: hip-and-knee-targeted exercise therapy for pain (SMD, 1.02; 95% CI: 0.58, 1.46) and function (SMD, 1.03; 95% CI: 0.61, 1.45), and knee-targeted exercise therapy and perineural dextrose injection for pain (SMD, 1.34; 95% CI: 0.72, 1.95) and function (SMD, 1.21; 95% CI: 0.60, 1.82). CONCLUSIONS: Six interventions had positive effects at 3 months for people with PFP, with no intervention adequately tested beyond this time point. J Orthop Sports Phys Ther 2022;52(11):750–768. Epub: 8 September 2022. doi:10.2519/jospt.2022.11359

Background and aims Patellofemoral pain (PFP) and patellofemoral joint osteoarthritis (PFJOA) are common non-self-limiting conditions causing significant pain and disability. The underlying pain pathologies lack consensus with evidence suggesting reduced pressure pain thresholds (PPTs) in adolescent females with PFP and individuals with knee osteoarthritis. A paucity of evidence exists for mixed-sex adults with PFP and PFJOA in isolation. Exploring if pain sensitisation is a dominant feature of PFP and PFJOA may have important implications for the delivery of a patient centred management approach. The primary aim was to measure local and remote PPTs in PFP and PFJOA patients compared to matched controls. Secondary aims were to evaluate the relationship between PPTs and (1) condition severity and (2) knee function. Methods 13 PFP patients plus 20 matched controls and 15 PFJOA patients plus 34 matched controls were recruited from a UK mixed-sex adult population. Controls were matched on age, sex and activity level. Demographic details, Tegner activity level score, symptom duration, condition severity (Kujala and KOOS-PF scores for PFP and PFJOA, respectively) and knee function (Modified Whatman score rating of five single leg squats) were recorded. PPTs were measured at six sites: five local around the knee, one remote on the contralateral leg. Between-group differences were tested using a two-way mixed model analysis of variance with repeated measures. Strength of association between PPTs and condition severity and knee function were tested using Spearman’s rank order correlation. Results No statistically significant difference in PPTs were observed between the PFP patients [F(1,31) = 0.687, p = 0.413, η2 = 0.022] or PFJOA patients [F(1,47) = 0.237, p = 0.629, η2 = 0.005] and controls. Furthermore, no correlation was found between PPTs and condition severity or knee function in PFP or PFJOA (p > 0.05). Conclusions Results suggest mechanical pain sensitisation is not a dominant feature of UK mixed-sex adults with PFP or PFJOA. Implications PFP and PFJOA remain persistent pain complaints which may not be well explained by objective measures of sensitivity such as PPTs. The findings suggest that peripheral pain processing changes leading to pain sensitisation is not a key feature in PFP or PFJOA. Instead the underlying pain pathway is likely to remain primary nociceptive, possibly with a subgroup of patients who experience pain sensitisation and might benefit from a more targeted management approach.