Vancomycin Oral Tablet / Capsule

Drug Class

Key Principle: Why Oral?

Vancomycin is poorly absorbed from the GI tract - this is actually the therapeutic rationale for oral use. The drug stays in the gut lumen at high concentrations, acting locally on intestinal pathogens.

• IV vancomycin is NOT effective for intestinal infections (does not reach the gut lumen in sufficient concentrations)
• Oral vancomycin is NOT effective for systemic infections (not absorbed)

FDA-Approved Oral Indications

Mechanism of Action

Dosing (Oral)

C. difficile Treatment Hierarchy (Current Guidelines)

1. Fidaxomicin - preferred first-line (lower relapse rates vs. oral vancomycin)
2. Oral Vancomycin - alternate first-line; preferred when cost is a concern
3. Metronidazole - no longer recommended as monotherapy (inferior cure rates)

Pharmacokinetics

Adverse Effects (Oral Route)

Resistance

• VRE (Vancomycin-Resistant Enterococci): Major concern; mediated by vanA and vanB gene transposons that alter the D-Ala-D-Ala target to D-Ala-D-Lac
• VISA / VRSA (S. aureus): Emerging resistance; isolated in patients with prolonged vancomycin therapy
• Resistance does not emerge rapidly from C. diff itself

Contraindications & Cautions

• Known hypersensitivity to vancomycin
• Not indicated for systemic infections when given orally
• Use with caution in inflammatory bowel disease (increased absorption)
• Avoid prophylactic use without clear evidence (routine prophylaxis during antibiotic therapy is discouraged due to microbiome disruption)

Available Formulations

Arthroscopic Fixation of AC Joint Subluxation / Dislocation

Anatomy & Mechanism of Injury

• Acromioclavicular (AC) ligaments - provide horizontal (anteroposterior) stability; the superior and posterior capsule are most important
• Coracoclavicular (CC) ligaments - the conoid (posteromedial) and trapezoid (anterolateral) provide vertical stability

Rockwood Classification

Three Requirements for Any AC Repair/Reconstruction

1. The AC joint must be exposed and debrided
2. The CC and AC ligaments must be repaired or reconstructed
3. Stable reduction of the AC joint must be achieved

Surgical Options: Three Categories of Reconstruction

Arthroscopic / Arthroscopically-Assisted Techniques

A. Suture Button (TightRope / EndoButton) Fixation

1. Patient in beach-chair position; arthroscopic portals established (posterior, anterolateral, anteromedial)
2. Arthroscopic exposure and identification of the coracoid base (subcoracoid space)
3. A guide pin is drilled from the superior clavicle (approximately 2.5 cm medial to the lateral end) down through the base of the coracoid
4. Tunnel is dilated over the guide pin
5. A suture tape or FiberWire is passed through the tunnel carrying a small titanium button (e.g., EndoButton, TightRope)
6. The subcoracoid button flips and seats under the coracoid base; the supraclavicular button is tightened and seated on the superior clavicle
7. The AC joint is reduced and the construct is tensioned
8. Optional: biologic graft augmentation (gracilis or semitendinosus allograft) is added to recreate conoid and trapezoid bundles for long-term stability

• Single-bundle - one device (1 tunnel in coracoid, 1 in clavicle)
• Double-bundle (EndoButton) - two separate corocoid-to-clavicle constructs to recreate conoid and trapezoid separately
• Triple-bundle - adds AC ligament reconstruction for horizontal stability

B. Arthroscopic Coracoacromial Ligament Transfer (Modified Weaver-Dunn)

• The coracoacromial ligament is detached from the acromion (arthroscopically) and transferred to the resected distal clavicle
• Historically popular but now largely replaced by anatomic CC reconstruction
• Meta-analyses show inferior functional and radiographic outcomes vs. CC ligament reconstruction

C. Anatomic Double-Bundle CC Reconstruction (Open/Arthroscopic-Assisted)

• Uses the coracoacromial ligament + conjoined tendon, or semitendinosus/gracilis allograft
• Tunnels are placed to recreate the conoid (4 cm from lateral clavicle) and trapezoid (2.5 cm from lateral clavicle) footprints anatomically
• Graft tails are used to recreate the anterosuperior and posterosuperior AC capsular ligaments

Why Avoid Bone Tunnels?

Complications of Arthroscopic AC Fixation

Hook Plate vs. Suture Button

Postoperative Care (General Principles)

• Sling immobilization for 4-6 weeks
• Pendulum exercises at 2 weeks
• Active ROM at 6 weeks
• Return to sport at 4-6 months (biologic healing of graft required)

Clavicle Fracture Classification

Epidemiology

• Most common fracture of the shoulder girdle
• 80% middle third, 15% distal third, 5% proximal (medial) third
• Most common fracture in children; 90% of obstetric fractures involve the clavicle

Classification Systems

1. Allman Classification (1967) - Anatomical / Location-Based

2. Craig / Neer Classification - Distal Third (Group II) Subclassification

3. Robinson Classification (1998) - Prognostic / Edinburgh System

• 2B2 (comminuted middle-third) = highest risk of nonunion and malunion
• 3B1 (displaced distal = Neer Type II) = highest nonunion risk in lateral fractures (~25%)
• Displacement >2 cm and comminution are the strongest predictors of poor outcome

4. OTA/AO Classification (Updated 2018)

Note: AO metaphyseal segments are shorter than one-third of the bone length (uses the "AO rule of squares" - the segment defined by a square whose side = widest dimension of the metaphysis).

Cross-Reference Summary Table

Key Clinical Points by Location

• Usually treated non-operatively (sling or figure-of-eight splint)
• Operative indications: open fracture, neurovascular injury, displacement >2 cm, shortening >1.5-2 cm, floating shoulder, polytrauma
• Nonunion rate: 1-3% (higher with displacement/comminution)
• Union expected: 6-8 weeks

• Type I and III - conservative (ligaments intact or intra-articular without instability)
• Type II - often operative due to ~25% nonunion risk (proximal fragment displaced upward by sternocleidomastoid; distal fragment held down by weight of arm)
• Methods: hook plate, CC screw, suture button, open reduction + ligament repair

• Rare; may mimic sternoclavicular dislocation clinically
• Plain radiographs unreliable - CT is mandatory to define fracture type and posterior displacement
• Posterior displacement can threaten mediastinal structures (great vessels, trachea, esophagus) - requires urgent evaluation

Bone Healing Types

TYPE 1: Indirect (Secondary) Bone Healing - with Callus

Phases of Indirect Bone Healing

Phase 1 - Inflammatory Phase (Days)

• Fracture causes haematoma - blood fills the fracture gap and forms a fibrin clot
• Bone necrosis occurs at the cut ends of fragments
• Platelets degranulate; cytokines released: TNF-α, IL-1, IL-6, IL-11, IL-18
• Neutrophils infiltrate → followed by macrophages
• Fibroblasts and capillaries proliferate → granulation tissue replaces haematoma (contains collagen type III and II)
• Mesenchymal stem cells arrive from periosteum, endosteum, and bone marrow
• Tissue at this stage tolerates up to 100% strain (maximum deformability)

Phase 2 - Reparative Phase (Weeks)

• Periosteal cells differentiate into chondroblasts → lay down fibrocartilage matrix
• Fibrocartilage soft callus forms at the fracture site - binds and stabilizes the ends
• Soft callus is flexible; tolerates 10-12% strain; tensile strength 4-19 N/mm²
• The extramedullary callus contributes far more to stability than intramedullary callus (bending stiffness increases with the 4th power of distance from the neutral axis)

• Osteoprogenitor cells from periosteum differentiate into osteoblasts → deposit woven bone on the outer surface (intramembranous)
• Simultaneously, the fibrocartilage calcifies and undergoes endochondral ossification → replaced by woven bone
• Hard callus: tolerates only 2% strain; tensile strength ~130 N/mm²
• Hard callus formation marks the end of the healing process and the beginning of the remodeling phase

Phase 3 - Remodeling Phase (Months)

• Woven bone is remodeled into lamellar (mature) bone by osteoclast/osteoblast units
• Callus volume decreases (visible on X-ray as callus index falls)
• Medullary canal is restored; cortical architecture is re-established
• Bone remodels along lines of mechanical stress (Wolff's law)
• Can continue for months to years until bone returns to original shape

Perren's Strain Theory (Key Concept)

"A little movement is good; too much movement is bad." - Bailey & Love

TYPE 2: Direct (Primary) Bone Healing - without Callus

Two subtypes of primary healing:

a) Contact Healing

• Fracture surfaces are in direct contact with < 0.01 mm gap
• Osteoclastic cutting cones tunnel directly across the fracture line
• Following osteoblasts lay down lamellar bone within the tunnel (osteons cross the fracture line)
• Bone is remodeled directly without an intermediate callus stage
• Requires compression forces and rigid fixation

b) Gap Healing

• Small gaps exist (0.01-1 mm) between fragments, too large for contact healing
• Gap is first filled with woven bone by direct osteoblastic deposition (intramembranous-like process)
• The woven bone is subsequently remodeled into lamellar bone by Haversian remodeling
• Occurs in areas where cutting cones have not yet bridged the gap

How Primary Healing Is Achieved Clinically

• Absolute compression at the fracture interface (e.g., lag screw, compression plate)
• No callus appears on post-op X-ray - this is normal and expected
• Rigid internal fixation that fails to achieve bone-to-bone contact (leaving a gap without compression) does not support primary healing

Comparison Summary

Failure of Healing: Terminology