Key points
The goals are anatomic reduction, restoring ACL tension, treating associated injuries, and fixation stable enough for early motion. [Kushare 2020]
- A tibial spine fracture (TSF) is a bony or chondral ACL avulsion, the paediatric equivalent of an ACL tear. Peak age 8 to 14.
- Get an MRI. Associated injuries are common (meniscus 32% to 59%, entrapment up to 65% in type III). MRI changed the grade in 32.5% of cases.
- Undisplaced fractures and type II fractures that reduce: cast or brace for 4 to 6 weeks with interval imaging.
- Type III and IV, failed reduction, displacement over 5 mm, entrapment, or repairable associated injury: arthroscopic or open reduction and fixation, ideally within 21 days.
- Screws and sutures give similar clinical results. Screws usually need removal (62.9% in one comparative series).
- Clear the block to reduction, usually the anterior horn of the medial meniscus or the intermeniscal ligament.
- Debride the bed and slightly recess the fragment to re-tension the stretched ACL.
- Protect the physis: epiphyseal screws or small (under 4 mm) or all-epiphyseal tunnels.
- Start motion within 4 weeks and avoid a cast after fixation. Arthrofibrosis (about 11%) is the most common complication.
- Warn about later ACL tear: 21.7% after operative treatment at a median of 3 years.
Epidemiology and mechanism
| Feature | Data |
|---|---|
| Incidence | About 3 per 100,000 per year, and rising with youth sport |
| Age | 8 to 14 typically. Mean age 12 (range 3 to 18) in the 2024 meta-analysis. |
| Share of knee injuries | 2% to 5% of children with a knee effusion. About 14% of ACL injuries. [Johnstone 2025] |
| Sex | More males (66.4% in the meta-analysis). The male excess appears only after age 10. Peak 13 to 14 in boys, 11 to 12 in girls. [DeFrancesco 2021] |
| Causes | Organised sport, bicycle falls, road traffic collisions, skiing and skateboarding |
Mechanism
- Forced flexion with tibial external rotation, external rotation on a planted foot, or hyperextension with valgus or rotation.
- The same loads tear the ACL in adults. In children the incompletely ossified tibial eminence is weaker than the ACL, so the bone fails first.
- ACL volume reaches adult values before the growth spurt, which may protect the ligament while the eminence is immature. [Tuca 2016]
- The ACL is usually plastically stretched during the injury, which partly explains residual laxity.
Classification
Both Meyers-McKeever and Green-Tuca are listed as validated systems. [Salvato 2023]
Meyers and McKeever (radiographic, 1959; type IV added by Zaricznyj 1977)
| Type | Description | Share in the meta-analysis |
|---|---|---|
| I | Undisplaced or minimally displaced | 7.2% |
| II | Anterior part elevated, posterior hinge intact | 44.3% |
| III | Completely displaced, no bony contact | 44.5% |
| IV | Displaced and comminuted | 4.0% |
Limit: ignores soft tissue injury and entrapment, which drive management.
Green and Tuca (MRI-based, 2019)
| Grade | Definition |
|---|---|
| I | Undisplaced or minimally displaced: 2 mm or less |
| II | Posterior hinge: anterior displacement over 2 mm, posterior 2 mm or less |
| III | Any of: posterior displacement over 2 mm, meniscal or intermeniscal ligament entrapment, or extension into the weight-bearing tibial plateau |
In the original series, MRI grading changed the grade in 32.5% of cases compared with Meyers-McKeever, changing the treatment recommendation. Interrater reliability among the Tibial Spine Research Interest Group has also been tested. [Ellis 2021]
Associated injuries and imaging
About a third of children have an associated injury. In the meta-analysis, 427 of 1,338 patients (31.9%) did: meniscal injury in 71% of these, ACL tear 11%, entrapment 11%, chondral 3%, collateral ligament injuries in the rest. Up to 69% has been reported in individual series.
| Injury | Data | Source |
|---|---|---|
| Meniscal injury | 32% to 59%, rising with fracture type | Tuca 2019, via Salvato 2023 |
| Meniscal tear pattern | 37% of 54 patients. 90% lateral. Most often posterior horn longitudinal tears, then anterior root detachment of the lateral meniscus (a functional meniscectomy, so reattach it). | Feucht 2017 |
| Entrapment | Anterior horn of the medial meniscus, intermeniscal ligament or anterior horn of the lateral meniscus. 26% of type II and up to 65% of type III. Seen even in type I. | Kocher 2003; Kushare 2020 |
| ACL injury | About 20% have some ACL injury (oedema to tear). Concomitant ACL injury up to 12% to 19%, more in older children. 20% of those later needed ACL reconstruction. | Mayo 2019; Ishibashi 2005 |
| Cartilage and loose bodies | Cartilage injury 7%, loose body 4% (58 patients, ages 5 to 18) | Mitchell 2015 |
Imaging
- Radiographs: first line. Can miss undisplaced fractures and all soft tissue injury.
- MRI: the gold standard for associated injuries, ACL integrity, fragment size and entrapment. It guides grading and surgical planning, and confirms reduction after closed treatment.
- CT: shows bony fragment detail and comminution.
- A passive extension block suggests incarcerated soft tissue.
Timing of surgery
Operate within 21 days. Delay is linked with more meniscal damage at surgery. [Smith 2022]
10 centres, 368 children treated surgically (mean age 11.7). The 21-day threshold came from an inflection point in the data and surgeon consensus.
| Finding | Result |
|---|---|
| Meniscal tear at surgery, under 21 days | 21.0% (61 of 290) |
| Meniscal tear at surgery, 21 days or more | 42.3% (33 of 78), P < .001 |
| Delay and meniscal injury | OR 2.8 (95% CI 1.6 to 5.0) |
| Predictors of delay: MRI 1 week or more after injury | OR 5.8 (95% CI 1.6 to 20.8) |
| Predictors of delay: diagnosis 1 week or more after injury | OR 3.8 (95% CI 1.1 to 14.3) |
| Predictors of delay: public insurance | OR 2.2 |
Nearly a third were diagnosed more than a week after injury. Delayed cases also had longer operations, and arthrofibrosis when surgery exceeded 2.5 hours.
Practical point: a child with a tense post-traumatic effusion or a lipohaemarthrosis should have an MRI within 1 to 2 weeks. [Gupte, BASK 2026, expert opinion]
Management algorithm
Tibial spine fracture management. Displacement and trapped tissue decide treatment; early motion follows fixation.
This is a consensus of expert practice, not a tested protocol. Entrapment is common even in type I and II fractures, so MRI often changes the path.
Closed reduction
Closed reduction can be tried for any displaced fracture. It is more likely to succeed with under 5 mm of anterior displacement in type II, and if done within 48 hours. Fewer than half of North American paediatric surgeons now attempt it for type II. [Kushare 2020]
Technique (Tibial Spine Research Interest Group)
- Analgesia. Aspirate the haemarthrosis and inject intra-articular local anaesthetic (for example ropivacaine 10 ml 0.75%). Supine on a radiolucent table.
- Flex the knee to 90 degrees to mobilise the fragment.
- Extend to about 30 degrees and perform a Lachman manoeuvre, holding anterior tibial translation. This tensions the ACL, draws the eminence posteriorly and frees entrapped tissue anteriorly.
- Keep the translation while fully extending the knee. Hold in terminal extension.
- Confirm on lateral fluoroscopy.
- Long leg cast in extension, not hyperextension.
- MRI after reduction to confirm position and look for associated injury. If reduction is inadequate, or there is a meniscal or ACL injury, proceed to arthroscopic fixation.
- After 3 weeks in cast: physiotherapy for motion, and weight-bearing as tolerated locked in extension for 3 more weeks.
Position of immobilisation
Not agreed. Full extension lets the lateral femoral condyle compress the fragment. About 20 degrees of flexion reduces ACL tension. Either way, interval imaging is mandatory to detect re-displacement. [Salvato 2023]
Operative technique
Arthroscopic (ARIF) and open (ORIF) fixation give similar outcomes. ARIF picks up more associated injuries and is preferred by many for smaller incisions, less pain and earlier motion. [Shimberg 2022, via Salvato 2023]
Arthroscopic steps [Kushare 2020]
- Portals and haematoma. Standard medial and lateral portals. Evacuate the haematoma promptly; long operations increase arthrofibrosis. Trim some fat pad to see the intermeniscal ligament.
- Bed preparation. Lift the fragment lip with a probe or elevator. Debride the bed with shaver, curette or burr until bleeding bone. Remove a little extra so the fragment sits slightly recessed, re-tensioning the stretched ACL.
- Clear the block. Usually the anterior horn of the medial meniscus or the intermeniscal ligament. Retract it with an outside-in suture passed through an 18G spinal needle under the structure.
- Reduce and hold. 0.045-inch K-wire from a superomedial or superolateral entry. The fragment is often translated laterally, so a lateral to medial wire lets you joystick it medially.
- Fix with screws or sutures (below).
- Check. Lachman, full range of motion (screws must clear the condyle in extension), and final fluoroscopy.
Screw fixation
- Best for a single large fragment. Not for small or comminuted fragments, which screws can split.
- Superomedial portal with the knee at 80 to 90 degrees. Two guidewires, then two partially threaded 4.0 mm cannulated screws, with washers if needed. A third screw through a superolateral portal for large fragments.
- Keep screws epiphyseal in skeletally immature patients. Take a true lateral image without moving the knee, to avoid bending the wire.
- Remove screws that cross an open physis. A suture tied to the screw head, or a K-wire through the cannulation, helps retrieval.
- Drawbacks: anterior impingement, cartilage damage and a high removal rate. Up to 66% had a second operation in one series. [Callanan 2019]
- Absorbable (including magnesium) screws avoid removal.
Suture fixation
- Technique of choice for small, chondral or comminuted fragments.
- Pass two or more high-strength sutures around the ACL base, for example with luggage-tag loops or a suture passer.
- Use an ACL guide to drill tunnels from the anteromedial tibia to the fracture bed, medial and lateral (or anterior and posterior) to the footprint. For type III, use three tunnels (centre, anterior and posterior) to create a suture bridge. Anterior tunnels are fine for type II with an intact hinge.
- Tie over a bone bridge at about 30 degrees of flexion, or use a button, or back up with a metaphyseal screw or knotless anchor.
- Physis: all-epiphyseal tunnels with fixation distal to the physis (Anderson principle), or small transphyseal tunnels. Use fluoroscopy to mark the physis first. Absorbable suture can limit tethering.
- Drawbacks: technically demanding, and risk of anterior malreduction.
Other options
Suture anchors, suture bridges, adjustable cortical buttons, K-wires, wire and absorbable nails have all been described. Fixation should withstand cyclic loads of about 300 to 450 N.
Biomechanics of fixation
In adult and porcine bone, sutures outperform screws. In paediatric bone, two screws and two sutures were equal, and sutures tied to metadiaphyseal anchors were strongest. [Johnstone 2025]
| Construct (paediatric cadaver, n = 6 each) | Ultimate failure load |
|---|---|
| Two 4.0 mm cannulated screws with washers | 143.5 ± 42.0 N |
| Two No. 2 sutures tied over a metaphyseal bone bridge | 135.4 ± 47.9 N |
| Two sutures secured to two 2.8 mm metadiaphyseal anchors | 225.5 ± 46.5 N |
- The suture-anchor construct was significantly stronger than both (P = .01 and P = .009).
- In the earlier study, sutures failed by pulling through the metaphyseal bone bridge. Anchors in stronger metadiaphyseal bone address this.
- All paediatric constructs failed at far lower loads than adult and porcine studies report. Adult biomechanical data do not translate directly to children.
- Limits: 6 knees per group (median age 8.5 to 9), a single type III fracture model, time-zero testing with no healing, and different specimen sets compared across studies.
Rehabilitation
There are no evidence-based guidelines. Early motion is the one consistent principle. [Kushare 2020]
- Starting motion within 4 weeks of treatment: arthrofibrosis 0% vs 36%, and full clearance at 103 vs 218 days. Immobilisation beyond 4 weeks gave 12 times higher odds of arthrofibrosis. [Patel 2012]
- After stable fixation, use immediate protected motion in a hinged brace, plus CPM if needed. Avoid a cast.
| Phase | Tibial Spine Research Interest Group (Kushare 2020) | Salvato 2023 |
|---|---|---|
| Range of motion | 0 to 90 degrees for 3 weeks (6 weeks if meniscus repaired) | 0 to 90 degrees for the first 4 weeks |
| Weight-bearing | Foot-flat for 2 weeks (6 weeks with meniscal repair) | Weight-bearing as tolerated from 4 weeks, brace 0 to 50 degrees. Stop crutches when gait is pain-free. |
| Exercises | Closed chain early. No open chain extension for at least 6 weeks. | Isometrics, active flexion with passive extension, hamstring work |
| Return to sport | 4 to 6 months. Healed fracture, full motion, strength within 90% of the other leg, functional tests. | 4 to 6 months after isokinetic and functional testing, with an ACL injury prevention programme |
Managing arthrofibrosis
- Dynamic splinting for extension and flexion, with physiotherapy.
- If that fails, arthroscopic lysis of adhesions plus gentle manipulation. Manipulation alone risks distal femoral physeal fracture: 3 of 32 children manipulated sustained one, with growth arrest. [Vander Have 2010]
- Some advocate routine arthroscopic screw removal and debridement at 3 months. [Parikh 2014]
Outcomes and complications
Outcomes are generally good whatever the approach or fixation. Fixation method made no significant difference to any complication. [Tibial Spine Research Interest Group 2024]
2024 meta-analysis at a glance
47 studies, 1,922 TSFs, mean age 12, all observational (11 level III, 36 level IV). ARIF 1,236, ORIF 291, non-operative 297. Screw 411, suture 586.
| Outcome | Overall | By fracture type (I and II vs III and IV) | Screw vs suture |
|---|---|---|---|
| Nonunion | 13 of 1,683 (0.7%), mostly type III treated non-operatively | 0% vs 1.7%, NS | 0 of 96 vs 1 of 84 |
| Arthrofibrosis | 190 of 1,700 (11.2%) | 8.6% vs 18.9%, NS | 45.3% vs 27.5%, NS (5 studies) |
| ROM loss | Reported in 35 studies | 3.8% vs 12.3%, RR 2.45, P < .001 | 45.3% vs 23.2%, NS |
| Residual laxity | Reported in 36 studies | 17.1% vs 22.6%, NS | 4.1% vs 0% |
| Secondary ACL injury | 63 of 1,476 (4.3%) | 28.9% vs 9.2%, RR 3.7, P = .008 | 8.1% vs 7.5% |
| Symptomatic hardware removal | One comparative study | n/a | 62.9% vs 9% |
ORIF vs ARIF: no significant difference in arthrofibrosis (15.9% vs 21.0%), ROM loss or secondary ACL injury.
Weighted mean Lysholm was about 92 to 97 in all subgroups. In 5 studies (n = 168), only 2 patients failed to return to their previous level. Mean return to sport was 6.5 months (2 studies).
Complications in detail
| Complication | Data |
|---|---|
| Arthrofibrosis | 10% to 29% after surgery. In a 10-centre study of 249 children, 23.3% developed arthrofibrosis and 7.6% needed manipulation. Independent risk factors: concomitant ACL injury (OR 20.0), non-sport trauma (OR 3.8), post-operative cast (OR 2.4), age under 10 (OR 2.2). [Bram 2020] Surgery over 2 to 2.5 hours also adds risk. Fixation method and approach are not risk factors. |
| Non-operative complications | Stiffness 19.4% and laxity 11.1% (systematic review). [Zhang 2021] |
| Residual laxity | Positive Lachman or anterior drawer in 20% to 60%, often up to 5 mm. Pivot shift positive in 8% to 40%. Laxity in up to 70% of displaced fractures treated non-operatively vs 14% treated surgically. Usually well tolerated. Pivot shift may predict function better. |
| Later ACL tear | 21.7% at a minimum of 2 years after operative treatment (median 36.4 months, n = 385), more after type III and IV. [O'Donnell 2021] ACL reconstruction for laxity or new injury in nearly 20%. |
| Nonunion | Under 2%, mostly non-operative or poorly reduced fractures, or entrapment. Presents with pain, extension loss and instability. |
| Growth disturbance | After transphyseal screws, and one case of overgrowth after suture fixation. Leg-length discrepancy in 6 of 420 (1.4%) after ARIF in one study. |
| Repeat fracture | 2 of 41 non-operatively treated type II fractures |
Critical appraisal and gaps
There are no randomised trials. The largest synthesis is 47 observational studies with no level I or II evidence.
Points to notice
| Source | What to notice |
|---|---|
| 2024 meta-analysis | Comparisons rest on small subsets (for example 5 studies, 144 patients, for screw vs suture). Definitions of arthrofibrosis and laxity vary between studies. The secondary ACL finding (more after type I and II) is probably confounded by unrecognised partial ACL injury. More associated injuries in ARIF probably reflect better detection, not more injury. Several authors report industry relationships. |
| Salvato 2023 | Expert narrative review. Its quoted later-ACL-tear rate (21.7%) applies to operatively treated fractures only. One senior author reports Arthrex consultancy and royalties. |
| Kushare 2020 | Technique paper of expert opinion from one research group, not comparative evidence. |
| Johnstone 2025 | Cadaveric, time-zero, 6 specimens per arm, one fracture pattern. Shows strength, not clinical benefit. |
Contradictions to note
- Biomechanics favour sutures in adult and porcine bone, but not in paediatric bone unless anchored to metadiaphyseal cortex.
- Raw rates of arthrofibrosis and ROM loss look higher with screws, but meta-analysis found no significant difference.
- The Green-Tuca classification is labelled validated, but evidence that it improves outcomes is lacking.
Research gaps
- Randomised or large prospective comparisons of screw vs suture, and of ARIF vs ORIF
- Optimal immobilisation position and duration for non-operative care
- Whether a lateral extra-articular procedure reduces residual laxity or later ACL tear after TSF fixation
- Long-term outcomes into adulthood
Expert opinion / unpublished data
Unit practice and data (Imperial, BASK 2026)
This section gives one unit's practice and unpublished results, presented at BASK 2026. It is expert opinion and local audit, not peer-reviewed evidence.
Indications for fixation
- Displacement over 2 mm (Green-Tuca grade II or III)
- Multifragmentary fracture
- Tissue interposition blocking reduction
- Poor compliance with non-operative care
Technique preferences
- Screws: for a single large fragment (over 10 mm). Avoid the physis. Leave in if asymptomatic, but beware impingement limiting extension and chondral abrasion from the condyle.
- Sutures: arthroscopic only and technically demanding, but the choice for multifragmentary fractures. Physeal tunnels under 4 mm. Can add a tibial suture anchor. A lateral extra-articular tenodesis (LET) can be considered to augment the repair.
- After suture fixation, check Lachman under anaesthesia. If still lax, add a suture anchor.
Imperial series (unpublished)
| Type | Fixation | n | Reoperation | Laxity (side-to-side) | Return to sport |
|---|---|---|---|---|---|
| II | Screw | 7 | 2 (impingement) | Under 2 mm | 7.5 months |
| II | Suture | 17 | 2 (arthrofibrosis) | Under 2 mm | 8.5 months |
| III | Suture | 15 | 1 (arthrofibrosis) | 2.45 mm | 7.9 months |
| III | Suture plus LET | 2 | 0 | 2.5 mm | 11.6 months |
Small numbers, non-randomised. Fixation was chosen by fragment type.
Unit rehabilitation protocol (Sportshealing)
| Phase | Content |
|---|---|
| Weeks 0 to 6 | Toe-touch progressing to full weight-bearing as tolerated. Brace locked in extension for walking and sleeping for 6 weeks. 0 to 90 degrees by week 3. Quads sets, straight leg raise. |
| Weeks 6 to 12 | Full weight-bearing, brace off at week 8. Stationary bike, closed chain, proprioception. 0 to 125 degrees by week 12. |
| Weeks 12 to 18 | Treadmill running from week 13. Squats, lunges, step-ups. |
| Weeks 18 to 24 | Plyometrics, agility and sport-specific drills |
| Full return to sport | 9 months |
This is longer than the 4 to 6 months in most published protocols. No plaster after surgery, since a cast is an independent risk factor for arthrofibrosis (OR 2.4). [Bram 2020]
Managing stiffness
- Extension not regained by 6 to 8 weeks: early arthroscopic arthrolysis, burring of any bone boss, and lateral notchplasty, ideally within 3 months.
- Reduced flexion: manipulation with arthroscopic arthrolysis.
Residual laxity and ACL reconstruction
Residual anterior laxity of 13% to 43% is reported, and most patients are asymptomatic. Consider ACL reconstruction after fixation for:
- symptomatic pivot-shift instability despite rehabilitation
- side-to-side difference over 3 mm with functional complaints
- nonunion or malunion with impingement or instability
- a young, high-demand athlete with residual laxity
The slides also quote a 10.6% ipsilateral ACL tear rate and 21% additional procedures at 5 years. Their source (Mayer 2019) could not be verified, so those figures are not used elsewhere on this page.
References
- Written by: [author name, role]
- Reviewed by: [clinical reviewer, role]
- Next review due: Oct 4, 2027
Core sources
- Tibial Spine Research Interest Group (Orellana KJ, Houlihan NV, Carter MV et al). Tibial spine fractures in the child and adolescent athlete: a systematic review and meta-analysis. Am J Sports Med 2024;52(5):1357-1366
- Salvato D, Green DW, Accadbled F, Tuca M. Tibial spine fractures: state of the art. J ISAKOS 2023;8:404-411
- Kushare I, Lee RJ, Ellis HB Jr et al. Tibial spine fracture management: technical tips and tricks from the Tibial Spine Fracture Research Interest Group. J Pediatr Orthop Soc North Am 2020;2(1)
- Johnstone TM, Hollyer I, McFarlane K et al. Improved biomechanical performance of tibial spine fracture repair with suture and anchor fixation in pediatric cadaveric knees. Orthop J Sports Med 2025;13(2):23259671241306194
Cited within the core sources
- Meyers MH, McKeever FM. Fracture of the intercondylar eminence of the tibia. J Bone Joint Surg Am 1959;41-A:209-222
- Green D, Tuca M, Luderowski E et al. A new, MRI-based classification system for tibial spine fractures changes clinical treatment recommendations when compared to Myers and McKeever. Knee Surg Sports Traumatol Arthrosc 2019;27(1):86-92
- Kocher MS, Micheli LJ, Gerbino P, Hresko MT. Tibial eminence fractures in children: prevalence of meniscal entrapment. Am J Sports Med 2003;31(3):404-407
- Feucht MJ et al. Meniscal injuries in children and adolescents undergoing surgical treatment for tibial eminence fractures. Knee Surg Sports Traumatol Arthrosc 2017;25(2):445-453
- Mayo MH et al. Anterior cruciate ligament injury at the time of anterior tibial spine fracture in young patients. J Pediatr Orthop 2019;39(9):e668-e673
- Bram JT et al. Four risk factors for arthrofibrosis in tibial spine fractures: a national 10-site multicenter study. Am J Sports Med 2020;48(12):2986-2993
- Patel NM, Park MJ, Sampson NR, Ganley TJ. Tibial eminence fractures in children: earlier posttreatment mobilization results in improved outcomes. J Pediatr Orthop 2012;32(2):139-144
- Vander Have KL et al. Arthrofibrosis after surgical fixation of tibial eminence fractures in children and adolescents. Am J Sports Med 2010;38(2):298-301
- Callanan M et al. Suture versus screw fixation of tibial spine fractures in children and adolescents: a comparative study. Orthop J Sports Med 2019;7(11):2325967119881961
- O'Donnell R et al. Anterior cruciate ligament tear following operative treatment of pediatric tibial eminence fractures in a multicenter cohort. J Pediatr Orthop 2021;41(5):284-289
- Shimberg JL et al. A multicenter comparison of open versus arthroscopic fixation for pediatric tibial spine fractures. J Pediatr Orthop 2022;42(4):195-200
- Zhang K et al. Management and complications in nonoperative fractures of the tibial spine: a systematic review. J Pediatr Orthop 2021;41(3):e272-e278
- DeFrancesco CJ et al. Pediatric tibial spine fractures: exploring case burden by age and sex. Orthop J Sports Med 2021;9(9):23259671211027237
- Ellis HB et al. Classification and treatment of pediatric tibial spine fractures: assessing reliability among a tibial spine research interest group. J Pediatr Orthop 2021;41(1):e20-e25
Additional sources
- Smith HE, Cruz AI Jr, Mistovich RJ et al. What are the causes and consequences of delayed surgery for pediatric tibial spine fractures? A multicenter study. Orthop J Sports Med 2022;10(3):23259671221078333
- Bram JT, Aoyama JT, Mistovich RJ et al. Four risk factors for arthrofibrosis in tibial spine fractures: a national 10-site multicenter study. Am J Sports Med 2020;48(12):2986-2993
- Gupte CM. Tibial spine fracture fixation. Instructional lecture, British Association for Surgery of the Knee (BASK), January 2026. Includes the unpublished Imperial series and unit rehabilitation protocol.