Surgical Approaches to the Elbow Joint

INTRODUCTION

1. Posterior approaches
2. Lateral approaches
3. Medial approach
4. Combined (Global) approach
5. Anterior approach

I. POSTERIOR APPROACHES

A. Campbell's Posterolateral Approach (Technique 1.107)

1. Deepen dissection through fascia, expose the triceps aponeurosis down to its olecranon insertion.
2. Free the aponeurosis in a tongue-shaped flap, reflecting it distally; incise remaining muscle fibers to bone in the midline.
3. Subperiosteal dissection exposes the joint. The ulnar nerve is identified and protected throughout.

B. Extensile Posterolateral Approach - Wadsworth (Technique 1.108)

1. Reflect skin flaps; isolate ulnar nerve proximally, release arcuate ligament, retract with rubber sling.
2. Fashion a distally based tongue of triceps tendon (leaving peripheral tendinous rim for repair), separating anconeus from extensor carpi ulnaris.
3. Reflect the triceps flap distally, divide posterior capsule.

C. Posterior Approach by Olecranon Osteotomy - MacAusland and Muller (Technique 1.109)

1. Straight posterior incision - 5 cm distal to olecranon tip, proximally medial to midline for 10-12 cm above olecranon.
2. Isolate ulnar nerve; retract with Penrose drain.
3. Pre-drill fixation hole (6.5 mm cancellous screw) before osteotomy.
4. Identify the bare zone of the olecranon. Mark a chevron osteotomy (~60 degrees, apex distal) at this bare zone.
5. Divide 3/4 of olecranon depth with thin oscillating saw; fracture the last 1/4 with an osteotome (to avoid cutting through articular surface).
6. Reflect olecranon with attached triceps proximally - excellent exposure of posterior distal humerus achieved.
7. Closure: Reduce and fix with lag screw + tension band wire.

D. Bryan and Morrey Extensile Posterior Approach (Technique 1.110)

1. Identify ulnar nerve at medial border of medial triceps head; dissect free to first motor branch. In TJA, transpose anteriorly into subcutaneous tissue.
2. Elevate medial aspect of triceps from humerus along intermuscular septum to the posterior capsule.
3. Incise superficial forearm fascia distally ~6 cm to periosteum of medial olecranon.
4. Reflect periosteum and fascia as a single unit medially to laterally. The medial junction between triceps insertion and forearm fascia/ulnar periosteum is the weakest point - careful sharp dissection with elbow extended 20-30 degrees.
5. To expose the radial head, reflect anconeus subperiosteally from proximal ulna - entire joint is now widely exposed.
6. Closure: Return triceps to anatomic position; suture through drill holes in proximal ulna. Suture periosteum to superficial forearm fascia.

II. LATERAL APPROACHES

A. Kaplan Lateral Approach (Technique 1.111)

1. Develop the interval between triceps posteriorly and ECRL/brachioradialis anteriorly to expose the lateral border of the humerus.
2. Important: In the proximal angle, avoid the radial nerve which passes between brachioradialis and brachialis.
3. Continue distally onto the condyle and proximal forearm.

B. Kocher Lateral "J" Approach (Technique 1.112)

III. MEDIAL APPROACH

Campbell's Medial Approach with Osteotomy of the Medial Epicondyle - Molesworth and Campbell (Technique 1.113)

1. Isolate ulnar nerve in its groove posterior to the epicondyle; free it and retract posteriorly.
2. Dissect all soft tissues from epicondyle except the common flexor origin; detach the epicondyle with an osteotome and reflect it distally with its attached flexor muscles.
3. Protect branches of median nerve supplying these muscles (entering along lateral margins).
4. Free the medial coronoid process; incise capsule; strip periosteum and capsule anteriorly and posteriorly.
5. Avoid injuring the median nerve passing anterior to the joint.
6. Dislocate the joint with the lateral capsule acting as a hinge - all articular surfaces can now be inspected.

IV. MEDIAL AND LATERAL (COMBINED) APPROACH (Technique 1.114)

V. GLOBAL APPROACH - Patterson, Bain and Mehta (Technique 1.115)

1. Dissect through deep fascia to triceps tendon and subcutaneous border of ulna.
2. Isolate ulnar nerve, open cubital tunnel, transpose anteriorly (protected with Penrose drain throughout).
3. Develop full-thickness medial or lateral fasciocutaneous flaps.

• Develop Kocher interval (anconeus - ECU) to expose capsule and lateral epicondyle.
• Reflect anconeus and triceps medially for olecranon fossa exposure.
• Elevate common extensor origin anteriorly for radial head exposure.
• Arthrotomy along anterior border of lateral ulnar collateral ligament, dividing annular ligament.
• If more radial head exposure needed: chevron osteotomy of lateral epicondyle.
• Forearm pronated to translate the posterior interosseous nerve anteriorly and protect it.

• Release flexor carpi ulnaris and flexor digitorum profundus subperiosteally from ulnar origins.
• Retract anteriorly to expose coronoid process, anterior bundle of medial ligament complex, and anterior joint capsule.

VI. ANTERIOR APPROACH

SUMMARY TABLE

NERVE-AT-RISK SUMMARY

• Ulnar nerve: At risk in ALL posterior and medial approaches. Always identify proximally first, protect with Penrose drain or rubber sling. Transpose anteriorly in arthroplasty.
• Radial nerve (main trunk): At risk proximally in lateral (Kaplan) approach.
• Posterior interosseous nerve (PIN): At risk in Kocher approach distally and in the global approach. Forearm pronation displaces PIN anteriorly, away from the operative field - a key protective maneuver.
• Median nerve: At risk in medial and anterior approaches - it crosses anterior to the joint.

Acid Fast Bacilli (AFB) - MS Ortho 20 Marks Answer

DEFINITION

I. ORGANISM

• Rod-shaped, non-spore-forming, thin, obligate aerobe
• Measures 0.5 μm × 3 μm
• Neutral on Gram staining (appear as "ghost" or "Gram-invisible" organisms)
• High lipid content in cell wall - mycolic acids, arabinogalactan, peptidoglycan form a waxy coat
• This lipid-rich cell wall makes them:
  • Resistant to desiccation
  • Resistant to most antibiotics
  • Responsible for acid fastness
  • Slow growing (doubling time ~20 hours; culture takes 4-8 weeks)

II. BASIS OF ACID FASTNESS

1. Bind the carbol fuchsin dye tightly
2. Form a hydrophobic barrier that resists decolorization with acid-alcohol (3% HCl in 95% ethanol)

• Nocardia (partially acid-fast with modified stain)
• Rhodococcus, Gordonia, Tsukamurella
• Legionella micdadei
• Protozoa: Cryptosporidium, Isospora (Cystoisospora)
• M. leprae (AFB causing leprosy)

III. STAINING METHODS FOR AFB

A. Ziehl-Neelsen (ZN) Stain - Classic Method

1. Flood smear with carbol fuchsin; heat gently to steam (3-5 min) - drives dye through lipid-rich wall
2. Decolorize with 3% acid-alcohol (HCl in 95% ethanol) - washes out dye from non-AFB
3. Counterstain with methylene blue or malachite green

B. Kinyoun Cold Stain (Modified ZN)

• Modification that excludes heating
• Uses higher concentration of carbol fuchsin to compensate
• Easier and safer to perform

C. Auramine-Rhodamine Fluorochrome Stain (Preferred Method)

• AFB fluoresce orange-yellow against a dark background
• More sensitive than ZN stain for screening
• Easier to scan under low magnification
• Requires fluorescence microscope (or LED microscope - now available in resource-limited settings)
• Most laboratories use this as the preferred initial stain for clinical specimens
• Positive fluorochrome smears are confirmed with ZN stain

Sensitivity Comparison:

• AFB smear sensitivity: 50-65%
• Culture sensitivity: 80-85%
• A positive smear indicates presence of mycobacteria but does not confirm species as M. tuberculosis

IV. SPECIMENS FOR AFB DIAGNOSIS IN ORTHOPAEDICS

V. CULTURE

• Gold standard for definitive diagnosis
• Specimens inoculated on:
  • Lowenstein-Jensen (LJ) medium (egg-based) - most widely used
  • Middlebrook 7H10/7H11 (agar-based) - allows colony morphology
  • MGIT (Mycobacteria Growth Indicator Tube) - liquid medium using fluorescent oxygen-sensitive compound; 10 days to 3 weeks positivity; WHO recommended reference standard
• Conventional solid medium: growth in 4-8 weeks at 37°C
• Modern liquid culture methods reduce time to 2-3 weeks

• Slow growing (>3 weeks)
• Buff/cream colored, rough, dry, wrinkled colonies
• "Cauliflower-like" or "serpentine cord" pattern microscopically (due to cord factor - trehalose-6,6-dimycolate)

VI. MOLECULAR DIAGNOSTICS

Xpert MTB/RIF (GeneXpert)

• WHO recommended for rapid diagnosis
• Detects M. tuberculosis DNA and rifampin resistance (rpoB gene mutation) in 2 hours
• For bone and joint TB: pooled sensitivity 81%, specificity 99% vs composite reference standard; 96% sensitivity vs culture
• Can be used on synovial fluid, tissue, pus, CSF

Line Probe Assays (LPA)

• Detects resistance to isoniazid (katG, inhA) and rifampin (rpoB)
• Used for MDR-TB screening

Drug Susceptibility Testing (DST)

• Universal DST recommended by WHO for all TB patients
• Rapid genotypic methods detect resistance to rifampin (rpoB), isoniazid (katG and inhA)

VII. MUSCULOSKELETAL / ORTHOPAEDIC TUBERCULOSIS

• M. tuberculosis disseminates hematogenously after acute or reactivated pulmonary infection
• Preference for metaphyses of long bones due to rich blood supply + scarcity of phagocytic cells
• Infection begins in subchondral region → spreads to cartilage, synovium, joint space
• Results in: metaphyseal erosion, cysts, cartilage loss, joint space narrowing

A. Spinal TB (Pott's Disease)

• Most common orthopaedic TB
• Adults: lower thoracic and upper lumbar vertebrae most commonly
• Children: upper thoracic spine
• Two or more adjacent vertebral bodies involved + intervertebral disc (disc early involvement is characteristic)
• Anterior superior or inferior angle of vertebral body affected first
• Collapse → kyphosis (gibbus deformity)
• Paravertebral cold abscess formation:
  • Upper spine: may track to chest wall
  • Lower spine: presents as psoas abscess tracking to inguinal ligament
• CT/MRI are diagnostic: vertebral body destruction, disc involvement, paravertebral abscess
• Catastrophic complication: Pott's paraplegia (abscess or lesion compressing spinal cord) - medical emergency requiring rapid drainage

B. Hip TB

• Involves head of femur
• Presents with pain and restricted movement
• If unrecognized: joint destruction

C. Knee TB

• Pain and swelling
• Synovial fluid: thick, high protein, variable cell count
• Culture positive in high percentage

D. Solitary vs Multicentric

• Immunocompetent: usually solitary lesion
• AIDS patients: multicentric distribution in ~30%

VIII. TREATMENT

Anti-Tubercular Therapy (ATT) - Standard Regimen

• Cure rate: >90% in drug-susceptible TB
• Daily administration throughout is recommended (intermittent regimens associated with higher failure/relapse/resistance)
• For musculoskeletal TB: extended treatment often used (6-18 months depending on site and response)

Drug Mechanisms

Surgical Indications in Orthopaedic TB

1. Pott's paraplegia (abscess decompression)
2. Failure of conservative management
3. Spinal instability / progressive kyphosis requiring stabilization
4. Large cold abscess requiring drainage
5. Diagnosis (biopsy) when culture/AFB inconclusive
6. Joint destruction requiring arthroplasty/arthrodesis

MDR-TB Treatment

• Defined as resistant to at least rifampin (RR-TB) or both isoniazid + rifampin (MDR-TB)
• Requires second-line agents: bedaquiline, linezolid, levofloxacin, moxifloxacin (Group A); clofazimine, cycloserine (Group B)

IX. EPIDEMIOLOGY

• 10.8 million new TB cases estimated globally in 2023 (WHO)
• 1.25 million TB deaths in 2023
• India accounts for 26% of global TB burden
• India is among 8 high-burden countries accounting for 2/3 of global cases
• Musculoskeletal TB: 1-5% of all TB cases; ~10% of extrapulmonary TB in developed nations

X. DIFFERENTIAL DIAGNOSIS OF AFB-POSITIVE LESIONS

SUMMARY

Acid Fast Bacilli (AFB)

MS Ortho — 20 Marks

I. DEFINITION

II. ORGANISM — MYCOBACTERIUM TUBERCULOSIS

• Rod-shaped, non-spore-forming, thin, obligate aerobe
• Size: 0.5 μm × 3 μm
• Neutral on Gram stain — appears as "ghost" or gram-invisible
• Slow growing — doubling time ~20 hours; culture takes 4-8 weeks
• The M. tuberculosis complex includes: M. tuberculosis, M. bovis, M. africanum, M. caprae, M. microti

1. Peptidoglycan (inner)
2. Arabinogalactan (middle)
3. Mycolic acids — long-chain, cross-linked fatty acids (outer, waxy coat)

• Binds carbol fuchsin tightly and resists acid-alcohol decolorization
• Reduces cell wall permeability → resistance to most antibiotics
• Causes slow growth and resistance to desiccation
• Gives characteristic microscopic "cord factor" appearance (trehalose-6,6-dimycolate causes serpentine cords)

• Nocardia (partially acid-fast, modified ZN stain)
• Rhodococcus, Gordonia, Tsukamurella
• Legionella micdadei
• Protozoa: Cryptosporidium, Isospora (Cystoisospora)
• Mycobacterium leprae (AFB causing leprosy)

III. STAINING METHODS

A. Ziehl-Neelsen (ZN) Stain — Classic Method

B. Kinyoun Cold Stain (Modified ZN)

• No heat required
• Uses higher concentration of carbol fuchsin to penetrate without heating
• Easier and safer to perform; widely used

C. Auramine-Rhodamine Fluorochrome Stain (Preferred for Clinical Specimens)

• AFB fluoresce orange-yellow against a dark background
• More sensitive than ZN for initial screening
• Scanned at lower magnification — faster and easier
• Positive results confirmed by ZN stain
• LED fluorescence microscopes now available in resource-limited settings

• AFB smear: 50-65% sensitivity
• Culture: 80-85% sensitivity
• A positive smear confirms mycobacteria present but does NOT confirm species as M. tuberculosis

IV. CULTURE (GOLD STANDARD)

• Buff/cream-coloured, rough, dry, wrinkled ("breadcrumb-like" or cauliflower appearance)
• Non-pigmented, slow-growing (>3 weeks)

V. MOLECULAR DIAGNOSTICS

Xpert MTB/RIF (GeneXpert)

• Detects M. tuberculosis DNA and rifampicin resistance (rpoB mutation) within 2 hours
• For bone and joint TB specimens: pooled sensitivity 81%, specificity 99% vs composite reference standard
• 96% sensitivity vs culture
• Can be used on synovial fluid, pus, tissue, CSF

Line Probe Assays (LPA)

• Detects resistance to isoniazid (katG, inhA genes) and rifampicin (rpoB)
• Used for rapid MDR-TB identification

Drug Susceptibility Testing (DST)

• WHO recommends universal DST for all TB patients
• At minimum: rifampicin resistance testing on all initial isolates

VI. SPECIMENS IN ORTHOPAEDIC PRACTICE

VII. MUSCULOSKELETAL TUBERCULOSIS

Epidemiology

• 4th most common extrapulmonary manifestation of TB
• Occurs in 1-5% of all TB patients
• <50% have radiographic evidence of pulmonary TB at presentation
• India bears ~26% of global TB burden (WHO 2023: 10.8 million new cases worldwide)

Pathogenesis

1. Droplet inhalation → alveolar macrophage phagocytosis
2. Primary pulmonary focus → hematogenous dissemination to skeletal sites
3. Predilection for metaphyses of long bones (rich blood supply, few phagocytes)
4. Infection begins in subchondral region → spreads to cartilage, synovium, joint space
5. Granuloma formation → central caseation → cold abscess (no signs of acute inflammation — hence "cold")
6. Disc involvement: spread from anterior angle of vertebral body to adjacent vertebra + disc

Distribution of Musculoskeletal TB

VIII. SPINAL TB (POTT'S DISEASE)

Vertebral Levels:

• Adults: lower thoracic + upper lumbar (T10-L2 most common)
• Children: upper thoracic spine

Pathological Stages:

1. Stage I (Synovitis/Pre-destructive): Soft tissue swelling, mild osteopenia
2. Stage II (Early destructive): Anterior wedging, disc space narrowing
3. Stage III (Late destructive): Vertebral collapse, kyphosis
4. Stage IV (Deformity): Gibbus (angular kyphosis), cold abscess, neurological deficit

Cold Abscess Tracking:

• Cervical spine: Retropharyngeal abscess → dysphagia/stridor
• Thoracic spine: Paravertebral abscess → may track along ribs to chest wall
• Lumbar spine: Psoas abscess → inguinal region, groin

Pott's Paraplegia (Catastrophic Complication):

• Abscess or granulation tissue compressing spinal cord
• Medical emergency — requires urgent drainage
• Early (within 2 years): due to abscess/granulation — responds to ATT ± drainage
• Late (>2 years): due to bony collapse/fibrous tissue — often requires surgery

Radiological Features:

• X-ray: Loss of disc space, vertebral end plate erosion, vertebral collapse, paraspinal shadow
• CT: Bony destruction, abscess extent, calcification
• MRI: Most sensitive (100%) and specific (88%) — vertebral body disease, disc destruction, cold abscess, cord compression; allows diagnosis before deformity develops

IX. HISTOPATHOLOGY — THE GRANULOMA

• Central caseous necrosis (cheese-like, acellular)
• Surrounded by epithelioid macrophages (activated macrophages)
• Langhans giant cells (peripheral nuclei in horseshoe arrangement) — pathognomonic
• Rim of lymphocytes
• Outer fibrous capsule

X. DIFFERENTIAL DIAGNOSIS

XI. ANTI-TUBERCULAR THERAPY (ATT)

Standard Regimen: 2HRZE / 4HR

Mechanism of Action

Musculoskeletal TB Duration:

• Spine TB (Pott's disease): 6-9 months (some centres extend to 12-18 months)
• Peripheral joint TB: 6-9 months
• Treatment is primarily conservative (ATT); surgery for specific indications

MDR-TB (Multi-Drug Resistant):

• Defined as resistance to rifampicin ± isoniazid
• Requires Group A drugs: bedaquiline, linezolid, levofloxacin/moxifloxacin
• Plus Group B: clofazimine, cycloserine

XII. SURGICAL INDICATIONS IN ORTHOPAEDIC TB

1. Pott's paraplegia — abscess drainage ± decompression (medical emergency)
2. Spinal instability — fixation and fusion
3. Progressive kyphosis (gibbus) — surgical correction
4. Diagnostic biopsy — when AFB/culture inconclusive
5. Large cold abscess not responding to aspiration
6. Joint destruction — arthroplasty or arthrodesis (after disease control with ATT)
7. Failure of conservative management

SUMMARY TABLE