Chronic Sclerosing Osteomyelitis of Garré

• Low-virulence organism in a bone with intact host defences produces a chronic reactive rather than destructive response.
• Organisms classically implicated: Actinomyces species (especially mandible, may follow dental extraction), Cutibacterium (Propionibacterium) acnes, coagulase-negative staphylococci, viridans streptococci, occasionally low-inoculum Staphylococcus aureus.
• Route: contiguous odontogenic spread in the jaw; haematogenous seeding in long bones; rarely post-traumatic.
• Chronic cytokine drive (IL-1, IL-6, TNF, RANKL/OPG shifts) stimulates periosteal and endosteal osteoblastic activity — the bone lays down more bone than it resorbs, giving sclerosis rather than lysis.
• Sclerotic, poorly vascularised bone is a pharmacological sanctuary: antibiotic penetration is poor, explaining the need for prolonged therapy and the tendency to relapse.

• CNO/CRMO/SAPHO are innate immune disorders — dysregulated IL-1β and IL-10 signalling in monocytes with excess TNF and IL-6, driving sterile osteitis.
• Monogenic models illuminate the pathway: IL1RN mutations (deficiency of the IL-1 receptor antagonist, DIRA), LPIN2 (Majeed syndrome), PSTPIP1 (PAPA syndrome) — all produce sterile bone inflammation.
• Associations: psoriasis, palmoplantar pustulosis, severe acne, inflammatory bowel disease, HLA-B27-related spondyloarthropathy.
• Osteitis proceeds through an inflammatory oedematous phase, then a reparative sclerotic/hyperostotic phase — hence the mixed lytic-sclerotic appearance evolving to dense sclerosis over years.

• In the mandible, chronic masticatory overload, parafunction and occlusal disharmony are implicated in diffuse sclerosing disease and explain the response to occlusal management.
• In long bones, repetitive loading may sustain periosteal reaction; a stress reaction/fracture must be excluded, as it produces identical fusiform cortical thickening.
• Local venous stasis and raised intraosseous pressure contribute to the deep, boring, night-predominant pain — the rationale behind medullary fenestration providing (often temporary) decompression relief.

Inspection. Patient exposed with both limbs visible (or the face symmetrically lit for mandibular disease). Look for a fusiform expansion of the shaft contour, comparing with the contralateral side. Look specifically for absence of a sinus or scar — a discharging sinus excludes Garré's and means classic chronic osteomyelitis. Inspect palms, soles, scalp and back for pustulosis, psoriasis and acne conglobata.

Palpation. Examiner's flat fingertips run along the subcutaneous border of the tibia or the mandibular body from posterior to anterior. Positive finding: a hard, smooth, non-mobile, tender expansion continuous with bone, without fluctuance and without overlying warmth or erythema. Tenderness is deep, localised to the segment, and reproducible on percussion.

Regional nodes. Palpate for cervical nodes (mandibular disease) or inguinal/popliteal nodes (lower limb). Significant lymphadenopathy raises malignancy or atypical infection.

Adjacent joints. Assess range of movement and effusion in the adjacent joint. Sterile sympathetic effusion may accompany metaphyseal CNO. In SAPHO, examine the sternoclavicular joints and anterior chest wall for hyperostotic swelling — this finding alone reframes the whole case.

Neurovascular. Mandibular disease: test inferior alveolar nerve sensation (lower lip/chin). Numbness (Vincent sign) is a red flag for malignancy or osteonecrosis, not simple sclerosing osteitis. Long bones: document distal pulses and nerve function before any surgery.

Spine and gait. CNO involves the spine in a meaningful minority — assess for a kyphotic angulation from vertebra plana and for antalgic gait.

There is no blood test that makes the diagnosis. Normal markers never exclude low-grade infection, and raised markers never confirm it.

Protocol: T1, fluid-sensitive fat-suppressed (STIR or T2 FS) in two planes, plus post-gadolinium T1 fat-suppressed sequences.

Whole-body MRI (coronal STIR head to toe) is the key investigation when multifocal sterile disease is suspected. It detects clinically silent lesions (clavicle, pelvis, spine, metaphyses), supports a CNO diagnosis pattern-wise, provides a safer biopsy target, and is radiation-free for repeated follow-up in children.

• Bone scintigraphy (Tc-99m): intense uptake in all three phases; sensitive but non-specific. Useful historically for detecting multifocality but largely superseded by whole-body MRI in children.
• FDG-PET/CT: may map multifocal disease and assess treatment response in SAPHO; radiation dose limits paediatric use.
• Ultrasound: limited role — can confirm absence of a subperiosteal collection and guide aspiration in soft-tissue swelling.
• Genetic testing: consider in very early-onset, severe or syndromic disease (IL1RN, LPIN2, PSTPIP1).

1. Aggressive imaging features or diagnostic uncertainty → sarcoma unit staging (local MRI, chest CT, bone scan/PET) and planned biopsy. Everything else waits.
2. CT nidus present → osteoid osteoma → radiofrequency ablation or en-bloc excision. Cure rate is high; recurrence managed by repeat ablation.
3. Sequestrum, abscess or sinus present → this is secondary chronic osteomyelitis, not Garré's → radical debridement, dead space management (antibiotic-loaded carrier), stabilisation and culture-directed antibiotics.
4. Organism recovered from 2 or more deep samples → prolonged culture-directed antibiotics, typically 3 to 6 months, with agents of good bone penetration; consider adjunctive fenestration if pain persists.
5. No organism, compatible histology and course → treat as CNO/SAPHO: NSAIDs first line, escalate medically, rheumatology co-management, whole-body MRI to confirm multifocality.
6. Refractory pain despite medical escalation → consider medullary fenestration/decortication understanding relief is variable and often temporary; document informed consent accordingly.

Principles: intravenous induction followed by oral step-down with high-bioavailability bone-penetrating agents; duration guided by clinical and radiological response and inflammatory markers; infectious diseases co-management mandatory; monitor for hepatotoxicity, marrow suppression, tendinopathy (fluoroquinolones) and C. difficile.

Antibiotics are not a treatment for sterile disease. Empirical prolonged antibiotic courses in culture-negative sclerosing osteitis expose patients to toxicity for no benefit and delay effective anti-inflammatory therapy.

Corticosteroids give short-term relief but are avoided as maintenance in the young.

• Eliminate odontogenic sepsis: extraction of non-restorable teeth, endodontic treatment, periodontal therapy — but be cautious in patients on bisphosphonates because of medication-related osteonecrosis risk.
• Occlusal adjustment, splint therapy and management of parafunction address the mechanical driver.
• NSAIDs first line; intravenous bisphosphonate infusion for refractory diffuse sclerosing osteomyelitis of the mandible has good evidence of analgesic benefit.
• Hyperbaric oxygen has been used adjunctively; evidence is limited and it is not standard of care.
• Decortication (removal of the dense outer cortex and periosteum) is reserved for refractory disease; recurrence is common. Resection with reconstruction is a last resort with substantial morbidity.
• Always exclude osteosarcoma of the jaw and metastatic disease before ascribing mandibular sclerosis to inflammation — lip numbness and rapid growth are red flags.

Position. Supine on a radiolucent table; sandbag under the ipsilateral buttock for the tibia; tourniquet high on the thigh (used but consider deflating before closure to secure haemostasis). Image intensifier from the contralateral side.

Imaging/equipment. Fluoroscopy; preoperative CT reformats on screen defining the sclerotic segment and canal; oscillating saw, fine osteotomes, high-speed burr, flexible reamers, bone biopsy trephine, multiple sterile specimen pots, antibiotic-loaded carrier (calcium sulphate beads) if infection suspected.

Preparation. Confirm no antibiotics given preoperatively unless septic; brief scrub team on the "clean instrument per sample" protocol; consent for possible sarcoma pathway conversion; group and save.

Approach. Tibia — direct anteromedial incision over the subcutaneous border, 1 cm medial to the anterior crest to avoid a wound over bone. Femur — lateral approach splitting the iliotibial band, vastus lateralis elevated anteriorly off the lateral intermuscular septum.

Dissection. Preserve periosteum where possible; incise longitudinally and elevate only the width of the intended window. Excessive stripping devascularises already compromised cortex.

Reconstruction/decompression step. Mark a rectangular window with rounded corners (stress risers at sharp corners cause fracture), typically 1 cm wide and no more than 30 to 50 percent of the bone diameter, sited away from the tension side. Use a drill-hole outline and fine osteotome or saw with continuous irrigation to avoid thermal necrosis. Harvest the cortical block as a specimen. Open the sclerotic medullary canal with a burr and gentle reaming until healthy bleeding bone is seen. Take the five deep samples. Irrigate with saline. Consider local antibiotic carrier if infection confirmed.

At-risk structures. Tibia — saphenous nerve and vein medially, anterior tibial artery deep to the interosseous membrane if over-penetrating laterally. Femur — perforating branches of the profunda femoris along the linea aspera (control with diathermy or ligation before they retract into the septum), sciatic nerve if dissection strays posteriorly.

Fixation. Usually none. If more than 50 percent of the diameter or more than 30 percent of the circumference is removed, or the bone is a weight-bearing femur, prophylactic intramedullary nailing or plating should be considered.

Closure. Layered closure over a drain if bleeding; avoid tight closure over the tibial subcutaneous border.

Aftercare. Protected weight bearing with crutches for 6 to 8 weeks with progressive loading; avoid impact and torsion for 3 months given the cortical window; radiographs at 6 weeks and 3 months to confirm window healing; continue medical therapy — surgery does not replace it.

Pitfalls. Sharp-cornered window causing fracture; over-resection; sampling burnt-out sclerosis giving false-negative histology; performing surgery for sterile inflammatory disease without medical escalation; failing to send tissue for mycobacterial culture.

Salvage of failure. Recurrent pain — repeat imaging to reassess for a missed nidus or malignancy before assuming relapse; escalate medical therapy; postoperative fracture treated with intramedullary nailing; established segmental infection may require resection with bone transport or vascularised fibular reconstruction.