The goal of this randomized clinical trial is to determine if administration of Exparel via local infiltration for medial patellofemoral ligament (MPFL) reconstruction procedures in pediatric orthopaedic sports medicine patients provides significant pain relief and decreased narcotic use. The main questions it aims to answer are:

• Does Exparel significantly reduce Visual Analog Scale (VAS) pain scores and pain levels up to one week postoperatively?
• Does Exparel significantly decrease narcotic use (number of pills taken) up to one week postoperatively?

Researchers will compare the pain outcomes and narcotic use of patients who receive Exparel and Marcaine via local infiltration to those of patients who receive only Marcaine via local infiltration for their MPFL reconstruction surgery. The goal is to understand if there is a significant difference in patient pain outcomes and narcotic use outside the first 24 hours postoperatively.

Participants will:

• receive either Exparel + Marcaine intraoperatively or Marcaine only intraoperatively during their MPFL reconstruction surgery
• receive and complete questionnaires at postoperative days 1, 4, and 7 regarding their pain scores, levels, and outcomes, effective pain treatments, overall pain interference, narcotic use (number of pills taken), and overall pain treatment satisfaction
• receive and complete secondary outcome measures of functional and psychological outcomes regarding their MPFL reconstruction surgery at postoperative day 1

This is a single institution, prospective, single-blinded (patient) randomized controlled trial to investigate the pain-control efficacy and patient reported pain outcomes of Exparel use in youth receiving MPFL Reconstruction. Participants will be randomized into two groups, Exparel + Marcaine or Marcaine-only. To be included, participants must be aged 10+ years at the time of surgery and present with an injury requiring an isolated MPFL reconstruction. Data will be collected from the patient's electronic medical record and from Oberd. Data collected will include age, height, weight, surgical information, diagnosis, patient reported outcomes (PROs) and patient demographics. 100 participants (50 per treatment group) will be enrolled in the study with a minimum of 80 needed to complete the study. Patients will be approached pre-operatively for participation, after which the surgical team will be informed. Patients will be offered the choice to participate in the study and randomize their treatment group. If patients do not want their treatment to be randomized, they will not be included in the study. Data collection will involve the Wong-Baker Visual Analog Scale (VAS) and VAS 10-centimeter line 0-10 Numeric Pain Intensity Scale, and an institution specific pain questionnaire regarding analgesic medicine intake and complications at postoperative day one, four and seven. A pain management patient satisfaction questionnaire will also be administered on post-operative day seven. Patients' medical records will also be reviewed for readmission, calls to their physician for pain, and other noted complications.

Patients will receive the following anesthesia doses by body weight (BW):

Pre-operatively:

• Regardless of age: 0.5 mg Midazolam per kg BW (intravenous, 15 mg maximum)
• If patient has history of PONV, 0.40 mg Emend per kg BW (pill), and 2 mg Midazolam (intravenous), and/or Scopolamine patch
• If patient has history of anxiety or PTSD, or exhibits anxiety symptoms before surgery: 0.1 mg Valium per kg BW (maximum 10 mg)

Intra-operatively:

• Amounts discretionary by patient vitals 0.5-1.0 mg Lidocaine per kg BW (intravenous -- no maximum) 3-4 mg Propofol per kg BW (no maximum) 1-2 mcg Fentanyl per kg BW (no maximum) 0.35 mg Ketamine per kg BW (no maximum) 0.1 mg Dexamethasone per kg BW (no maximum) If necessary: 0.004 - 0.006 mg Hydromorphone per kg BW (no maximum)
• Optional:

10-20 mcg Dexmedetomidine per kg BW (for persistent tachycardia) <50% Nitrous If intubated/ventilated: 0.5-0.6 mg Rocuronium per kg BW, ~2 mg/kg Sugammadex for reversal If Tranexamic Acid administered: 15 mg per kg BW (10-15 min intravenous, maximum 1 g) For maintenance: 1 Minimum Alveolar Concentration (MAC) Sevoflurane and 15 mg Acetaminophen per kg BW (maximum 1 g) If necessary during emergence: 0.004-0.005 mg Hydromorphone per kg BW, 0.5 mg Ketorolac per kg BW (maximum 30 mg), and 0.1 mg Ondansetron per kg BW (maximum 4 mg)

- If PACU medication required: 0.004-0.006 mg Hydromorphone per kg BW and 0.10- 0.15 mg Oxycodone per kg BW, and Metoclopramide, Dexamethasone, Promethazine, or Ondansetron

Exparel + Marcaine Group:

- Local Infiltration: Regardless of weight: 10 mL Exparel and 10 mL 0.25% Marcaine

Marcaine Only Group:

- Local Infiltration: Regardless of weight: 20 mL 0.25% Marcaine

Post-Operatively:

• Days 1-3: Alternate weight-adjusted Acetaminophen and 10 mg Ketorolac every 3 hours
• Days 4-7: Alternate weight-adjusted Acetaminophen and Ibuprofen every 3 hours
• Days 1-5: 40 mg Famotidine every 12 hours
• Rescue: Weight-adjusted Tramadol taken with Acetaminophen for severe pain (every 6 hours, maximum 8 doses) The investigators will enroll 50 patients in each treatment group with 40 in each group needed for a sufficiently powered analysis. Patients will not be informed of their treatment group until after the study is complete.

Inclusion Criteria:

• Must be aged 13+ years at time of surgery
• Must present with injury requiring an isolated MPFL Reconstruction
• Ability to provide assent, legally appointed representative available to provide informed consent

Exclusion Criteria:

• Patient <13 years old
• Requires fracture repair or another non-standardized surgery
• Any MPFL Reconstruction that requires the use of arthrotomy or a tibial tubercle osteotomy
• Any lower extremity procedure that is not an isolated MPFL Reconstruction
• Patient pregnancy
• Inability to provide assent or legally appointed representative to provide informed consent
• Prior history of hypersensitivity to Exparel or any local anesthesia
• BMI ≥ 40

Patients will be randomized after consent is obtained and will not know if they receive Exparel intraoperatively.