High-yield overview
4 typesType I undisplaced through Type IV comminuted
Paediatric ACL equivalenttibial spine avulsion = the child's ACL tear
Types III–IVrequire reduction and fixation (arthroscopic or open)
Peak age 8–14the intercondylar eminence fuses by the late teens
Critical Must-Knows
- The Meyers-McKeever classification grades tibial intercondylar eminence (spine) fractures by displacement and is the essential decision-making tool for the paediatric knee.
- Type I is undisplaced, Type II has a hinged posterior cortex, Type III is fully displaced (often rotated), and Type IV (Zaricznyj addition) is comminuted. Types I and II are managed non-operatively in a cast or brace; Types III and IV almost always require surgical reduction and fixation.
- A tibial spine fracture in a child is biomechanically equivalent to an ACL tear in an adult — the ligament fails by avulsing its bony attachment rather than by mid-substance rupture because the incompletely ossified tibial eminence is the weak link.
- Residual laxity and stiffness are the two main complications. Over-reduction must be avoided (entrapment of the anterior horn of the meniscus or the intermeniscal ligament can block reduction and cause extension loss).
The threshold examiners want
Types I and II can be treated non-operatively in a cylinder cast or hinged brace in extension (or near-extension) for 4 to 6 weeks. Types III and IV almost always require operative reduction and internal fixation — arthroscopic suture fixation or screw fixation is the modern standard. If a Type II fracture fails to reduce or maintain reduction on follow-up imaging, it escalates to operative management. Always check for entrapment of the anterior horn of the medial meniscus or the intermeniscal ligament — this blocks reduction and is the commonest reason a Type II or III fails closed management.
The Meyers-McKeever Classification (with Zaricznyj Type IV)
The tibial intercondylar eminence (spine) is an unossified or partially ossified ridge in the child. An acute valgus-external rotation or hyperextension force avulses the ACL from its tibial footprint. The classification is based on the degree of displacement of the fracture fragment.
| Type | Description | Displacement | Management |
|---|---|---|---|
| I | Undisplaced or minimally displaced | Fragment in anatomic position | Non-operative: cylinder cast or brace in extension for 4–6 weeks |
| II | Hinged — posterior cortex intact | Anterior third to half elevated; posterior hinge intact | Trial of extension casting; if residual gap on lateral X-ray, consider operative fixation |
| III | Fully displaced | Complete separation from the tibial bed; may be rotated | Arthroscopic (or open) reduction and fixation — suture or screw |
| IV | Comminuted (Zaricznyj addition) | Multiple fragments | Arthroscopic reduction and fixation; often suture-based as screw purchase is poor in comminuted bone |
Mnemonic
UHDC — Undisplaced, Hinged, Displaced, Comminuted (U Have Done Correctly when you fix III and IV)The four types
Clinical Pearl
The posterior horn of the medial meniscus and the intermeniscal ligament can become interposed between the fragment and the tibial bed — this is the commonest cause of a failure to reduce a Type II or III fracture. If the lateral radiograph shows a persistent gap despite extension casting or intra-operative extension, suspect soft-tissue interposition and explore arthroscopically.
Anatomical and Biomechanical Rationale
- Why children avulse bone rather than tear the ACL. The incompletely ossified tibial eminence is the weakest point in the ligament-bone complex in the skeletally immature knee. The ACL itself has superior tensile strength to its chondroepiphyseal insertion, so the failure mode is bony avulsion rather than mid-substance rupture.
- Peak incidence is 8 to 14 years. The eminence ossifies progressively; before approximately 8 years the cartilaginous eminence rarely fractures in isolation, and after the mid-teens the ossified eminence is strong enough that the ligament itself tears (adult-pattern ACL injury).
- Mechanism of injury is classically a hyperextension or valgus-external rotation force — the same mechanism as an ACL tear. A fall from a bicycle, a sporting twisting injury, or a direct blow to the flexed knee are typical presentations.
- Associated injuries include meniscal tears (up to a quarter of cases in some series), chondral damage, and collateral ligament injury. Always image and examine the entire knee, not just the spine.
Mnemonic
Child's bone gives way before the ligament — C-B-G-W-B-T-L — Cartilage Before Growth, Weaker Bone Than LigandWhy bone avulses in children
Clinical Presentation and Imaging
- Presentation. A child or adolescent with an acute traumatic haemarthrosis of the knee, pain, inability to weight-bear, and a positive Lachman test or anterior drawer. The haemarthrosis may be tense.
- Plain radiographs. Lateral view is the key film — it demonstrates the elevation of the fragment and the degree of displacement. The AP view may show the eminence fragment superimposed on the intercondylar notch. A tunnel (notch) view can also be helpful.
- CT is useful for surgical planning in Types III and IV to assess fragment size, comminution, and displacement direction. It is not mandatory for Types I and II.
- MRI identifies associated soft-tissue injuries (meniscal tears, chondral damage, partial ACL tears of the remnant) and confirms the integrity of the posterior cortex hinge in Type II. It is increasingly recommended for Types II–IV.
Key X-ray finding
The lateral radiograph shows elevation of the tibial spine fragment from the tibial plateau. Measure the gap between the fragment and its bed — a gap of more than 2 mm is considered displaced (Type II or III).
Pitfall
An ossifying tibial eminence in a younger child can appear irregular on X-ray and mimic a fracture. Correlate with clinical examination (haemarthrosis, instability) and compare with the contralateral knee if in doubt.
Management by Type
| Type | Initial Management | If Reduction Fails / Persistent Gap | Rehabilitation |
|---|---|---|---|
| I | Cylinder cast or hinged brace in extension or near-extension for 4–6 weeks | Not applicable (already reduced) | Range-of-motion at 4–6 weeks; progressive weight-bearing; physiotherapy for quadriceps and proprioception |
| II | Trial of extension casting or hyperextension manoeuvre; repeat lateral X-ray to confirm reduction | If gap persists or fragment does not reduce: arthroscopic reduction and fixation | Same timeline as Type I if non-operative; post-operative protocol if fixed |
| III | Arthroscopic reduction and fixation (suture or screw); check for meniscal or intermeniscal ligament interposition | If fragment is rotated or soft tissue is interposed: remove the block, reduce, and fix | Hinged brace; range-of-motion from 2 weeks; weight-bearing as tolerated in brace by 4–6 weeks |
| IV | Arthroscopic reduction and suture fixation (screw fixation often unsuitable due to comminution) | If fragments are too comminuted for fixation: debride small loose pieces and reattach the ACL remnant to the tibial bed with sutures through transosseous tunnels | Same as Type III post-operative protocol; may need slower progression if fixation tenuous |
Caution
Never accept persistent displacement in Type III/IV fractures. Unreduced tibial spine fractures heal in a raised position, producing a bony block to full extension and residual ACL laxity. Late reconstruction is more complex and yields inferior results compared with early anatomical reduction.
Complications and Outcomes
- Residual ACL laxity. Reported in a significant minority of patients even after anatomical reduction and fixation. Mechanisms include plastic deformation of the ACL before avulsion, interposed tissue healing in a lengthened position, and insufficient fixation. Patients and families should be counselled about this possibility up front.
- Loss of extension (arthrofibrosis). The most common complication after surgical fixation, particularly if immobilisation is prolonged or rehabilitation is delayed. Early range-of-motion in a hinged brace reduces the risk.
- Meniscal injury. The anterior horn of the medial meniscus or the intermeniscal ligament can be trapped beneath the fragment, blocking reduction. This must be identified and released at the time of surgery.
- Growth disturbance. Rare, because the fracture is through the chondroepiphyseal region rather than the physis itself. However, in very young children or with transphyseal fixation techniques, the risk must be considered. Avoid transphyseal hardware when possible in the skeletally immature.
- Non-union or malunion. Uncommon with operative management of displaced fractures; non-operative management of Type II with a persistent gap carries a higher risk of malunion in a displaced position.
Mnemonic
Laxity, Arthrofibrosis, Meniscal entrapment, Extension loss — LAMEComplications — LAME
Evidence Base
Evidence
Fracture of the intercondylar eminence of the tibia
Meyers MH, McKeever FM • J Bone Joint Surg Am (1959)
Key Findings:
- Original classification of tibial intercondylar eminence fractures into three types based on displacement
- Recommended non-operative treatment for undisplaced fractures and operative reduction for displaced fractures
- Established the clinical and radiographic criteria still used today
Clinical implication: The foundational classification for tibial spine fractures in children that remains the standard for clinical decision-making.
Limitation: Small retrospective case series; no long-term functional outcomes reported.
Source: J Bone Joint Surg Am 1959;41-A(2):209-220
Evidence
Avulsion fracture of the tibial eminence: treatment by open reduction and pinning
Zaricznyj B • J Bone Joint Surg Am (1977)
Key Findings:
- Proposed the Type IV (comminuted) addition to the Meyers-McKeever classification
- Recognised that comminuted fragments require a different fixation strategy to the original three types
- Described outcomes with open reduction and pinning techniques
Clinical implication: Extended the classification to include comminuted fractures, recognising that these need special consideration for fixation method.
Limitation: Expert opinion and case report; no comparative data.
Source: J Bone Joint Surg Am 1977;59(8):1111-1114
Evidence
Tibial eminence fractures in children: prevalence of meniscal entrapment
Kocher MS, Micheli LJ, Gerbino P, Hresko MT • Am J Sports Med (2003)
Key Findings:
- Identified meniscal or intermeniscal ligament entrapment in a high proportion of displaced tibial eminence fractures requiring operative intervention
- Meniscal entrapment was the commonest cause of failed closed reduction in Type II and III fractures
- Recommended arthroscopic assessment for all displaced fractures to identify and release interposed soft tissue
Clinical implication: Highlighted the importance of checking for meniscal interposition — the commonest cause of irreducible tibial spine fractures — and the need for arthroscopic evaluation in displaced types.
Limitation: Retrospective review; single-centre experience.
Source: Am J Sports Med 2003;31(3):404-407
Evidence
Biomechanical comparison of four different fixation techniques for pediatric tibial eminence avulsion fractures
Mahar AT, Duncan D, Oka R, Lowry A, Gillingham B, Chambers H • J Pediatr Orthop (2008)
Key Findings:
- Compared four fixation techniques (suture, screw, and others) biomechanically in a paediatric tibial eminence fracture model
- Suture fixation provided equivalent or superior load-to-failure compared with screw fixation
- Supports the use of physeal-sparing suture techniques that avoid transphyseal hardware in skeletally immature patients
Clinical implication: Biomechanical evidence supports suture fixation as a robust alternative to screw fixation, avoiding hardware-related complications and respecting the physis.
Limitation: Biomechanical study (porcine or sawbone model); no clinical outcome data.
Source: J Pediatr Orthop 2008;28(2):159-162
Guidelines, Registries and Global Practice
- No single universal guideline. Management of paediatric tibial spine fractures is guided by the Meyers-McKeever classification and institutional protocols rather than a single society-level guideline. The AO Foundation and POSNA (Pediatric Orthopaedic Society of North America) teaching broadly follow the classification-based algorithm described above.
- Fixation technique varies by region. Arthroscopic suture fixation is increasingly the global standard, particularly for Types III and IV, because it avoids hardware-related complications and respects the physis. Screw fixation remains common in centres with established expertise, particularly for large single fragments (Type III). Open reduction is reserved for irreducible or complex comminuted fractures.
- Non-operative vs operative threshold. There is broad international consensus that Types I and II are managed non-operatively (with the caveat that a Type II that does not reduce or maintain reduction is elevated to operative management). Types III and IV are almost universally treated operatively. This consensus spans North American (POSNA), European (EPOS), and Australasian practice.
- Rehabilitation protocols. Centres vary in the timing of range-of-motion initiation (immediate vs 2 weeks post-operative) and weight-bearing progression (4 vs 6 weeks). Early motion is increasingly favoured to reduce arthrofibrosis risk.
Exam Viva
Practise clinical reasoning and management decisions out loud
Viva scenarioStandard
Clinical prompt
“A 12-year-old boy fell from his bicycle and landed on his right knee. The knee is swollen and tense. Lachman test demonstrates anterior laxity with a soft endpoint. The lateral radiograph shows the tibial spine fragment elevated approximately 5 mm from its bed with a posterior hinge intact. How would you classify and manage this injury?”
Practical approach
This is a Meyers-McKeever Type II tibial spine fracture — the fragment is hinged posteriorly with elevation of the anterior portion. I would first assess for associated injuries (meniscal tear, chondral damage) with an MRI. For a Type II fracture, the initial management is a trial of closed reduction by extending or hyperextending the knee under sedation or in theatre, followed by a cylinder cast or hinged brace in extension. I would obtain a lateral radiograph in the cast to confirm the fragment has reduced anatomically. If the fragment reduces and maintains position, I would manage non-operatively with 4 to 6 weeks of immobilisation followed by rehabilitation. If the fragment does not reduce, if there is a persistent gap on the lateral film, or if MRI demonstrates meniscal interposition blocking reduction, I would proceed to arthroscopic reduction and fixation — typically suture fixation through transosseous tunnels. I would counsel the family about the risk of residual ACL laxity and stiffness.
Key clinical points
Classify as Meyers-McKeever Type II (hinged, partially displaced)
Trial of closed reduction with extension casting; confirm reduction on lateral X-ray
Escalate to arthroscopic fixation if reduction fails or meniscal tissue is interposed
Counsel about residual laxity and arthrofibrosis risk
Common pitfalls
Assuming all Type II fractures can be managed non-operatively — a persistent gap or meniscal entrapment requires surgery
Forgetting to check the lateral radiograph in the cast to confirm reduction
Not counselling the family about the possibility of residual ACL laxity even after successful reduction
Further questions
“How would your management change if the fragment were fully displaced and rotated (Type III)?”
“What are the fixation options for a Type III fracture and what are the relative advantages of each?”
“How do you manage residual ACL laxity after a healed tibial spine fracture?”
Viva scenarioAdvanced
Clinical prompt
“You are asked to see a 10-year-old girl with a fully displaced, rotated tibial spine fracture (Meyers-McKeever Type III). At arthroscopy, the anterior horn of the medial meniscus is interposed between the fragment and the tibial bed and cannot be reduced. How would you proceed?”
Practical approach
This is a common operative finding in Type III fractures — the anterior horn of the medial meniscus or the intermeniscal ligament is trapped beneath the fragment, blocking reduction. I would first gently retract the meniscus to expose the fragment and the tibial bed. I would clear the bed of any haematoma or fibrous tissue to create a raw surface for healing. I would then reduce the fragment anatomically, confirming reduction under direct vision and with image intensifier. For fixation, I would use arthroscopic suture fixation — passing non-absorbable sutures through the ACL remnant near its insertion on the fragment, then through transosseous tunnels drilled across the proximal tibial epiphysis, tying the sutures over the anterior tibial cortex. This avoids screw-related complications such as hardware irritation and the need for a second procedure for removal, and it avoids transphyseal hardware. I would carefully inspect the meniscus for any peripheral tear that may have resulted from the entrapment and repair it if found. Post-operatively, I would place the knee in a hinged brace and begin gentle range-of-motion at approximately 2 weeks to minimise arthrofibrosis, with progressive weight-bearing. I would follow up with serial radiographs to confirm maintenance of reduction and union.
Key clinical points
Identify and release the interposed meniscus — the commonest block to reduction in Type III
Clear the fracture bed to allow anatomical reduction
Suture fixation through transosseous tunnels avoids hardware complications and respects the physis
Inspect the meniscus for associated tears and repair if needed
Early mobilisation to reduce arthrofibrosis
Common pitfalls
Attempting to force reduction without releasing the interposed meniscus — this can damage the meniscus or ACL remnant
Using screw fixation in a small or comminuted fragment that may not hold screw threads
Forgetting to check for an associated meniscal tear — the entrapment mechanism can cause a peripheral meniscal injury
Prolonged immobilisation post-operatively increases arthrofibrosis risk
Further questions
“What are the advantages of suture fixation over screw fixation for tibial spine fractures?”
“How would you manage a patient who develops significant residual ACL laxity 12 months after a healed Type III fracture?”
“What is the risk of growth disturbance with transphyseal fixation techniques?”
Exam day cheat sheet
Meyers-McKeever Classification — Exam Cheat Sheet
The four types
- Type I: undisplaced — cast or brace in extension for 4 to 6 weeks
- Type II: hinged (posterior cortex intact), anterior third to half elevated — trial extension casting; fix if persistent gap
- Type III: fully displaced, may be rotated — arthroscopic reduction and fixation (suture or screw)
- Type IV: comminuted (Zaricznyj addition) — arthroscopic reduction and suture fixation
Key decision points
- Types I and II: non-operative (with the caveat that a Type II that does not reduce needs surgery)
- Types III and IV: operative — arthroscopic reduction and internal fixation
- Always check for meniscal or intermeniscal ligament interposition — the commonest cause of irreducible fracture
- Counsel families about residual ACL laxity even after anatomical reduction
Complications and pitfalls
- Residual ACL laxity: common even with good reduction (plastic deformation of the ACL before avulsion)
- Arthrofibrosis: most common post-operative complication; early range-of-motion reduces risk
- Meniscal entrapment: blocks reduction; must be identified and released at surgery
- Growth disturbance: rare but consider with transphyseal fixation in the skeletally immature