Study the Reconstructive Rearfoot/Ankle Part I by practicing planal decomposition: for every deformity vignette, name the classification, assign each finding to the transverse, sagittal, or frontal plane, state what is fixed versus flexible, and map one corrective procedure to each plane. Confirm current exam format and administration details directly with ABFAS.
Why Planal Analysis Should Organize Your Flatfoot Review
Treat every rearfoot deformity as a three-plane problem: hindfoot valgus sits in the frontal plane, forefoot abduction in the transverse plane, and arch collapse with forefoot position in the sagittal plane. Each plane then points to specific corrective procedures.
Decomposition begins with the exam description in the vignette. Hindfoot valgus means an everted calcaneus relative to the lower leg. Forefoot abduction at the transverse tarsal joint produces the too-many-toes sign and talonavicular uncoverage on weight-bearing films. Midfoot collapse is sagittal, and correcting the hindfoot may unmask a forefoot varus that must then be addressed in its own right. Throughout, separate flexible from fixed deformity: passively correctable components can be handled by realignment through mobile joints, while fixed components demand osteotomies or fusion of the joints that are deformed.
Attach named gait-analysis concepts to each finding. The single-heel-rise test probes posterior tibial tendon function: inability to invert and rise implicates the tendon rather than only the bones. The transverse tarsal joint locks when the hindfoot is everted and unlocks when it is inverted, which is why a valgus hindfoot transmits abduction forces into the midfoot. Then map procedures to planes: a medializing calcaneal osteotomy addresses frontal-plane valgus, a lateral column lengthening addresses transverse-plane abduction, and a plantarflexion correction of the medial column addresses the sagittal forefoot component. A plan missing one plane leaves that deformity behind.
Staging Adult-Acquired Flatfoot: What Changes at Each Stage
The Johnson and Strom flatfoot staging, modified by Myerson, separates tendon-only disease from flexible deformity, then fixed deformity, then ankle involvement. The stage determines which joints are addressed, so stage the patient before selecting procedures.
Stage I is posterior tibial tendon dysfunction with normal alignment: the tendon is painful and dysfunctional, but the single-heel rise is preserved and the foot is not yet deformed. Stage II is a flexible deformity, with later subdivisions distinguishing lesser forefoot abduction from severe abduction and subtalar joint involvement; check your reference text for the exact subdivision criteria rather than memorizing a single summary. Stage III adds a fixed hindfoot deformity with subtalar joint involvement, and Stage IV extends the deformity to the ankle with valgus talar tilt. The vignette clues that matter are passive correctability, degree of talonavicular uncoverage, subtalar motion, and any ankle valgus.
The practical consequence is joint-preserving versus joint-sacrificing logic. Stages I and II preserve mobile joints, so correction relies on osteotomies and soft-tissue procedures matched to each plane of deformity. Stage III involves joints that are themselves deformed and stiff, so realignment fusion of the involved joints becomes the reasoning path. Stage IV means the ankle cannot be ignored and must be incorporated into the plan. When you read a vignette, force yourself to state the stage aloud and explain which finding moved the patient into that stage before you write a single procedure.
| Stage | Deformity character | Joint involvement | Simplified corrective logic |
|---|---|---|---|
| I | Tendon pain and dysfunction with preserved alignment | None | Tendon-focused management |
| II | Flexible deformity; subdivisions by abduction severity and subtalar findings | Mobile joints; forefoot abduction, hindfoot valgus | Osteotomy plus tendon transfer matched to each plane |
| III | Fixed hindfoot deformity | Subtalar joint involved | Realignment fusion of the involved joints |
| IV | Deformity extends to the ankle with valgus tilt | Ankle joint involved | Ankle addressed alongside hindfoot reconstruction |
Worked Scenario: Sequencing a Flexible Stage II Flatfoot Reconstruction
In a flexible stage II flatfoot, the stronger decision is to map each finding to a plane-specific procedure instead of defaulting to one osteotomy or reaching for fusion. The scenario below shows the mapping and the mistake to avoid.
Paper scenario: a flexible stage II flatfoot with hindfoot valgus, substantial forefoot abduction with marked talonavicular uncoverage, a positive too-many-toes sign, and no arthritis on imaging. When the examiner passively corrects the hindfoot, a forefoot varus appears, meaning the medial column needs plantarflexion once the hindfoot is realigned. The subtalar joint is mobile and painless. This is the profile in which joint preservation is the reasoning target: every joint remains mobile and every deformity component can be addressed by realigning bone while keeping joints intact.
A plausible mistake is recommending an isolated flexor digitorum longus transfer. A soft-tissue transfer substitutes lost tendon power, but it does not correct the osseous components of valgus and abduction in this scenario, so the deformity persists under load. The better decision maps each finding: a medializing calcaneal osteotomy for frontal-plane valgus, a lateral column lengthening for transverse-plane abduction, the flexor digitorum longus transfer to restore the sagittal-spanning invertor power, a gastrocnemius recession for equinus contribution, and a medial column plantarflexion procedure for the unmasked forefoot varus. It matters because the same patient could have been pushed toward fusion unnecessarily or left with residual abduction.
Ankle Fractures: Using Weber and Lauge-Hansen Together
The Danis-Weber system classifies the fibula fracture by level relative to the syndesmosis; Lauge-Hansen describes the injury mechanism and ligament sequence. Use Weber for quick communication, then reason with Lauge-Hansen to anticipate medial and syndesmotic injury.
Danis-Weber places the fibula fracture below the syndesmosis (A), at its level (B), or above it (C). Lauge-Hansen names the foot position at injury and the deforming force: supination-adduction, supination-external rotation, pronation-external rotation, and pronation-abduction, each with numbered stages that describe the order in which bony and ligamentous structures fail. A Weber B fibula pattern corresponds broadly to a supination-external rotation mechanism, but the fibular level alone does not tell you the status of the deltoid ligament or the syndesmosis. That gap is exactly why the two systems are taught together rather than as substitutes for each other.
Worked scenario: an ankle injury described as a Weber B fibula fracture, with tenderness extending proximally along the medial side and a widened medial clear space on the injury radiographs. The mistake is stopping at the Weber label and assuming the injury stops at the fibula. The better decision recognizes the supination-external rotation pattern with medial-side failure, and plans to assess syndesmotic stability after fibular fixation, since a stable construct with an unstable syndesmosis changes the fixation plan. It matters because the classification is not a final answer; it predicts which structures you must evaluate and in what sequence the injury likely progressed.
The Ankle Arthritis Decision Ladder: Preservation Before Fusion
Sort ankle arthritis into a reasoning ladder: arthroscopic debridement for limited disease, realignment through the joint for asymmetric arthritis with salvageable cartilage, then fusion or arthroplasty for end-stage disease. Justify each rung by joint condition, not preference.
Build the ladder from the condition of the joint rather than from a list of operations. Localized disease with preserved motion supports arthroscopic debridement reasoning. Asymmetric arthritis, such as varus or valgus collapse with focal cartilage loss on one side and a correctable deformity, supports supramalleolar osteotomy reasoning: realign the weight-bearing axis so remaining cartilage carries load. End-stage, global cartilage loss moves the discussion to fusion or arthroplasty, where the deciding factors in a vignette are deformity correctability, adjacent joint arthritis, and the demands described in the case. Practice stating which rung a vignette lands on and why the rungs below it were excluded.
Train the boundary conditions with contrast pairs. A vignette describing medial-sided ankle pain, varus malalignment, and a joint that corrects passively with the heel in a neutral position pushes reasoning up the ladder toward realignment. A vignette describing global joint space loss, stiff painful motion, and arthritis in the subtalar or neighboring joints pushes reasoning toward fusion, with the arthroplasty question hinging on deformity and adjacent-joint status. Rehearsing these contrasts builds the habit of connecting the radiographic description to the joint-preservation argument, which is the reasoning the scenario format rewards rather than a memorized single answer.
Tendon Disorders: Transfer Logic Versus Lengthening Logic
Tendon decisions turn on two distinct questions: a contracture driving deformity calls for a lengthening at the correct level, and a lost or weakened tendon calls for a transfer that substitutes its function. Distinguish the two before planning.
The Silfverskiold test separates isolated gastrocnemius tightness from Achilles-level contracture: dorsiflexion that improves with the knee flexed localizes the tightness to the gastrocnemius, while limited dorsiflexion in both knee positions implicates the Achilles complex. That finding chooses the level of recession. On the deforming-force side, posterior tibial tendon insufficiency produces progressive valgus and collapse, while peroneal involvement shapes varus and cavus patterns, with peroneus longus overpull plantarflexing the first ray. Naming the tendon, its deforming direction, and its flexibility status gives you the inputs for the operative logic.
Transfer logic then has three parts worth rehearsing. First, the donor should be in phase with the muscle it replaces and have compatible excursion and strength, which is the usual reasoning for the flexor digitorum longus substituting the posterior tibial tendon. Second, a transfer substitutes muscle power but does not correct fixed bone position, so it follows osseous realignment rather than replacing it. Third, in neuromuscular patterns, balancing is part of the plan: removing a deforming force without restoring opposing balance invites recurrence. Practice explaining each part for one transfer you choose, using the tendon anatomy rather than a memorized procedure list.
Cavovarus Sequencing With the Coleman Block, Plus Your Self-Check Rubric
In cavovarus deformity, the Coleman block test separates forefoot-driven from hindfoot-driven varus, and that result sequences the plan. Use the exercise and rubric below to turn planal decomposition into a repeatable, timed skill.
The Coleman block reasoning: place the lateral forefoot and heel on a block so the first ray hangs free. If the hindfoot varus corrects, the deformity is forefoot-driven, typically through a plantarflexed first ray, and correction begins with the first ray, such as a dorsiflexion procedure of the first metatarsal, with peroneus longus transfer reasoning available where the longus overpull is part of the pattern. If the hindfoot stays varus, the deformity is hindfoot-driven or fixed, pointing to a lateralizing calcaneal osteotomy with any first-ray correction layered by findings. In neuromuscular cavovarus, such as Charcot-Marie-Tooth patterns, imbalance between strong invertors and weakening evertors drives the deformity, so tendon balancing accompanies the bony plan.
Exercise: take five deformity vignettes from your question bank, ideally two flatfoot, one ankle fracture, one arthritis, and one cavovarus. For each, within five minutes, write five lines: the named classification, the planal decomposition, the fixed-versus-flexible call, one procedure mapped to each plane, and a joint-preservation statement. Expected observations: your first attempts will probably name procedures without a plane assignment, or miss the forefoot component unmasked by hindfoot correction; that is the habit to break. Rubric, two points per line, ten total: reach eight or more on two consecutive vignettes before moving topics. These scores are learning milestones only, not predictions of exam performance.
Readiness checks before you sit the exam: you can stage a flatfoot from a written description and say which finding set the stage; you can give both a Weber and a Lauge-Hansen reading of a fracture and name what each adds; you can state where an arthritis vignette sits on the preservation ladder and why the lower rungs fail; you can predict Coleman block results from the first-ray findings; and you can complete the five-line mapping for a new vignette in under five minutes without notes.
References and further reading
Use these references to explore the concepts and check the latest information from the relevant organizations.