A Systematic Review of the Systematic Utilitarian Procedure for Extremity Reconstruction of the Hip (SUPERhip) for Congenital Femoral Deficiency with Reference to Recent Extra-network Cohort Findings

Abstract

Aims and background

Congenital femoral deficiency (CFD) is a rare limb anomaly requiring Hip reconstruction before femoral lengthening. The Systematic Utilitarian Procedure for Extremity Reconstruction of the Hip (SUPERhip), introduced by Paley in 1997, is the principal protocol for type Ib and type II CFD. No systematic review has consolidated outcomes in this population. This review synthesised radiographic outcomes, complications and protocol fidelity.

Materials and methods

PubMed, Google Scholar, Literatura Latino-Americana e do Caribe em Ciências da Saúde (LILACS) and China National Knowledge Infrastructure (CNKI) were searched in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 [International Prospective Register of Systematic Reviews (PROSPERO) CRD420261386450]. Eligible studies were peer-reviewed cohorts of three or more patients with Paley type Ib or type II CFD (subtypes IIa and SUPERhip-eligible IIb) treated with the full SUPERhip protocol. Single-arm narrative synthesis was performed; meta-analysis was not feasible due to outcome reporting heterogeneity.

Results

Two cohorts met the inclusion criteria: Paley et al. (106 procedures, 1997–2012) and Violante Júnior et al (26 patients, 2005–2020). Outcome reporting was structurally asymmetric: Paley et al. (pooled n = 106) reported reduction with bone morphogenic protein 2 (BMP2) – delayed ossification (41% → 13%) and recurrent varus (37% → 11%) (p < 0.005 for both); Violante Júnior et al. reported radiographic indices [neck-shaft angle (NSA): 72° → 133°; centre-edge angle (CEA): 17° → 34°; and acetabular index (AI): 28° → 16°, all p < 0.001]. Neither cohort reported medial proximal femoral angle (MPFA). Protocol fidelity ranged from canonical practice through within-network variants to extra-network adaptations.

Conclusion

The SUPERhip procedure achieves substantial radiographic correction in Paley type Ib CFD; a within-cohort signal from a single primary dataset suggests that fixed-angle fixation with intra-osseous BMP2 may reduce late complications. Outcomes are reported asymmetrically; no peer-reviewed type-II-specific cohort outcomes exist; MPFA is reported in no cohort; and the evidence base remains concentrated within a single methodological lineage.

Clinical significance

Hip reconstruction before femoral lengthening is supported by comparator literature for both type Ib and type Ia CFD. Within this limited evidence base, canonical SUPERhip with fixed-angle fixation and BMP2 is the best-evidenced approach for type Ib; a within-network supply-constrained variant achieved comparable radiographic correction. Late Hip instability is a post-lengthening risk in type Ia CFD.

Introduction

Congenital femoral deficiency (CFD) is a rare congenital limb anomaly with an estimated incidence of 1–2 per 1,00,000 live births.¹ The condition is characterised by shortening, abnormal development and pathological Hip and knee joints, with clinical presentations ranging from mild proximal femoral varus to complete absence of the femur.^2–4 Paley's classification, introduced in 1998 and now the most widely used framework, stratifies CFD by the development and ossification of the proximal femur into types I (continuous femur with normal or delayed ossification), II (absent femoral neck), III (absent proximal femur) and IV (absent distal femur).^2,5 Type Ia denotes normal proximal femoral ossification; type Ib denotes delayed ossification of the femoral neck (Ib₂), subtrochanteric region (Ib₁) or both (I₃); type IIa, IIb and IIc denote a mobile, fused or absent femoral head, respectively.^2,6

Treatment of types Ib and II requires Hip joint reconstruction before femoral lengthening,⁷ since lengthening across an unstable or malformed Hip carries a substantial risk of subluxation and dislocation.^8–12 The Systematic Utilitarian Procedure for Extremity Reconstruction of the Hip (SUPERhip), introduced by Paley in 1997, addresses this requirement through four integrated components: Extra-articular soft-tissue releases [tensor fascia lata (TFL), rectus femoris, iliopsoas and piriformis], abductor relative lengthening via iliac shortening (the Soutter–Campbell-derived abductor slide),¹³ subtrochanteric multiplanar realignment osteotomy correcting varus, flexion and retroversion, and pelvic osteotomy to address acetabular dysplasia.^2,14,15 The procedure has evolved over three decades to incorporate fixed-angle fixation constructs and, more recently, intra-osseous bone morphogenic protein 2 (BMP2) for cases with persistent femoral neck delayed ossification.^14,16,17

Despite the SUPERhip procedure's central place in CFD reconstruction, no systematic review has consolidated its outcomes specifically in the Paley type Ib and type II populations for which it was designed. Existing reviews of CFD treatment are typically cohort-level reports of lengthening outcomes or narrative chapters synthesising the developing technique.^2,8,14,18,19 A formal systematic review is warranted because (1) multiple primary cohorts have now been published from different centres, (2) the procedure has undergone substantive technical evolution within the originating institution, and (3) extra-network adaptations have emerged whose outcomes warrant comparison against the canonical protocol.

This review aimed to synthesise the available evidence on radiographic outcomes, range of motion, complications and protocol fidelity of the SUPERhip procedure in Paley type Ib and type II CFD.

Materials and Methods

Protocol and Registration

This systematic review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 statement.²⁰ The protocol was registered prospectively with the International Prospective Register of Systematic Reviews (PROSPERO) (CRD420261386450, registered 4 May 2026).

Eligibility Criteria

Studies were eligible for inclusion if they met all of the following criteria: (1) peer-reviewed publication; (2) cohort of three or more patients with Paley type Ib or type II CFD (type II restricted to subtypes IIa and SUPERhip-eligible IIb and type IIc excluded as it is treated with pelvic support osteotomy rather than the SUPERhip protocol); (3) treatment with the full SUPERhip protocol comprising all four canonical components – extra-articular soft-tissue releases, abductor slide via iliac shortening, subtrochanteric multiplanar realignment osteotomy and pelvic osteotomy; and (4) report of at least one outcome of interest (radiographic indices, range of motion, complications or downstream lengthening outcomes). No language or date restrictions were applied. Studies reporting type Ia cohorts only, partial-fidelity SUPERhip variants, technique descriptions without cohort outcomes, case reports of fewer than three patients and conference abstracts without full publication were excluded. Type Ia cohorts were retained as adjacent literature for the discussion.

Information Sources and Search Strategy

PubMed, Google Scholar, Literatura Latino-Americana e do Caribe em Ciências da Saúde (LILACS) and China National Knowledge Infrastructure (CNKI) were searched from inception to 4 May 2026. The search strategy combined medical subject headings and free-text terms for CFD, proximal focal femoral deficiency (PFFD), SUPERhip and related procedures. Reference lists of all included studies, identified narrative reviews and adjacent-literature publications were hand-searched. Author networks and expert recommendations were canvassed for unpublished or in-press cohorts.

Selection Process

Records were de-duplicated and screened in Rayyan.²¹ Title and abstract screening was undertaken independently by two reviewers; full-text review followed for any record passing initial screening or with ambiguous classification. Disagreements were resolved by discussion. The final inclusion set, exclusion reasons and screening counts are presented in the PRISMA flow diagram (Fig. 1).

Fig. 1.

PRISMA 2020 flow diagram

Data Extraction and Risk of Bias

A pre-specified extraction form captured study identifiers, cohort characteristics (sample size, age range, sex distribution, Paley subtype distribution and follow-up duration), surgical technique (soft-tissue release components, fixation construct, pelvic osteotomy variant and BMP2 use), radiographic outcomes [neck-shaft angle (NSA), centre-edge angle (CEA),²² acetabular index (AI),²³ medial proximal femoral angle (MPFA), Sharp–Ullmann index²⁴ and antetorsion angle], range of motion, complications and downstream lengthening outcomes where available. Risk of bias was assessed at the cohort level using a structured framework adapted from the Joanna Briggs Institute checklist for case series, with explicit attention to (1) whether radiographic indices were reported in canonical pairs (NSA with MPFA per Paley's framework), (2) whether outcome ascertainment captured both during-lengthening and late-post-lengthening endpoints and (3) whether the cohort was independent of, or methodologically affiliated with, the originating Paley Institute network.

Synthesis Methods

Single-arm narrative synthesis was undertaken in accordance with the Synthesis Without Meta-analysis (SWiM) guideline.²⁵ Quantitative pooling was not feasible due to outcome reporting heterogeneity between included cohorts. Cohort independence was verified through institutional affiliation, surgeon attribution and direct correspondence with the senior authors of included studies. Where the same outcome was reported in multiple cohorts, descriptive comparison was undertaken without pooling. Protocol-fidelity assessment was undertaken across the included cohorts and across extra-network adaptations identified through citation chasing, with each cohort coded against eight canonical SUPERhip technical axes.

Results

Search Results

The database search yielded 199 records after deduplication. Following title and abstract screening, 47 reports were assessed for eligibility. Citation searching of included full texts and hand-searching of identified review reference lists did not identify additional eligible reports beyond those already retrieved. After full-text review, two cohort studies met the inclusion criteria for synthesis (Fig. 1).

Study Characteristics

Paley et al. reported on 122 primary SUPERhip procedures performed at the Paley Institute between 1997 and 2012, of which 72 procedures in 72 patients met that paper's inclusion criteria for the type Ib₂/Ib₃ ‘neck’ group; together with 34 revision procedures, the analysed denominator was 106 procedures.¹⁴ Mean age at primary surgery was 3.6 years (range: 16 months–23.5 years); mean follow-up was 5.5 years (range: 6 months–12.8 years). Violante Júnior et al. reported on 26 patients with type Ib CFD treated at the Associação de Assistência à Criança Deficiente (AACD) and Instituto de Assistência Médica ao Servidor Público Estadual (IAMSPE) in São Paulo, Brazil, between October 2005 and March 2020.¹¹ Mean age was 7 years (range: 1–18 years), with 17 female and nine male patients. Twenty patients (76.9%) underwent primary procedures; six had undergone previous surgery.

Patient independence between the two cohorts was confirmed. Paley et al. explicitly state that all procedures were performed by the senior author at the Paley Institute, whereas Violante Júnior et al.'s procedures were performed in São Paulo by the AACD/IAMSPE team.¹⁴

Radiographic Outcomes

Radiographic outcomes are summarised in Table 1. Violante Júnior et al. reported significant pre/post improvement in all three measured indices: NSA increased from 72.3° ± 7.1° to 133.1° ± 12.7° (mean change: +60.8°, p < 0.001); CEA increased from 16.8° ± 9.8° to 33.5° ± 14.1° (p < 0.001); AI decreased from 27.8° ± 6.9° to 16.4° ± 6.8° (p < 0.001).¹¹ The MPFA, the second of Paley's canonical dual-target indices for proximal femoral correction, was not reported.¹² Range of motion improved significantly in abduction (32.1°–44.3°, p < 0.001), internal rotation (3.0°–31.2°, p < 0.001) and external rotation (corrected from 80.8° to 51.3°, p < 0.001). The pre/post indices and the Sheffield 2025 comparator values are displayed in Figure 2. Paley et al. did not report any radiographic indices or range-of-motion outcomes for the synthesis cohort.¹⁴

Table 1.

Radiographic and range-of-motion outcomes (Violante Júnior et al.). Paley et al. did not report any radiographic indices or range-of-motion data; cells are omitted accordingly

Index	Preoperative (mean ± SD)	Postoperative (mean ± SD)	p-value
NSA (°)	72.3 ± 7.1	133.1 ± 12.7	<0.001
CEA (°)	16.8 ± 9.8	33.5 ± 14.1	<0.001
AI (°)	27.8 ± 6.9	16.4 ± 6.8	<0.001
MPFA (°)	Not reported	Not reported	–
Hip abduction (°)	32.1 ± 9.3	44.3 ± 13.3	<0.001
Internal rotation (°)	3.0 ± 10.2	31.2 ± 17.1	<0.001
External rotation (°)	80.8 ± 10.0	51.3 ± 17.4	<0.001

AI, acetabular index; CEA, centre-edge angle; MPFA, medial proximal femoral angle; NSA, neck-shaft angle; SD, standard deviation

Fig. 2.

Radiographic outcomes – preoperative vs postoperative

Complications and Stratified Outcomes

Complications are summarised in Table 2. Paley et al. stratified the primary cohort (n = 72) into three sequential technique eras based on fixation construct and BMP2 use: Non-fixed angle without BMP2 (n = 34, 1997–2002), fixed angle without BMP2 (n = 11, 2002 onwards) and fixed angle with BMP2 (n = 27, later cases). The incidence of recurrent varus deformity decreased across the three groups (53%, 9% and 7%; non-fixed vs fixed without BMP2, p = 0.027); the incidence of persistent delayed ossification decreased across the three groups (53%, 36% and 4%; fixed without BMP2 vs fixed with BMP2, p = 0.045). Pooled across primary and revision procedures (n = 106), the incidence of delayed ossification fell from 41% (28/68) without BMP2 to 13% (5/38) with BMP2 (p = 0.0034); recurrent varus fell from 37% (25/68) to 11% (4/38) (p = 0.004).¹⁴ The within-cohort effect is shown in Figure 3.

Table 2.

Complications by cohort. Paley et al. values are extracted from the pooled (primary + revision) analysis (Table 6 of the original publication); within-primary-cohort era stratification is shown separately in Figure 3. The era-stratified subtotals (G1 + G2 + G3) sum to 21 recurrent varus and 23 delayed ossification cases and could not be fully reconciled with the primary-cohort totals reported in the source (26 and 25); the internally consistent pooled figures are therefore used here

Complication	n (%)	Notes
Paley et al. (n = 106 pooled)
Recurrent varus	25 (37%) → 4 (11%)	Reduced from 37% (without BMP2, n = 68) to 11% (with BMP2, n = 38); p = 0.004
Persistent delayed ossification	28 (41%) → 5 (13%)	Reduced from 41% (without BMP2, n = 68) to 13% (with BMP2, n = 38); p = 0.0034
Subluxation/dislocation	Not reported	Mean follow-up: 5.5 years; 6-month minimum may underdetect late instability
Violante Júnior et al. (n = 26)
Total complications	4 (15.4%)	All in patients ≤5 years at surgery; 0 in patients >5 years (p = 0.011)
Non-union	2 (7.7%)
Wound dehiscence	1 (3.8%)
Implant failure (broken plate)	1 (3.8%)	120° LCP
Subluxation during the SUPERhip phase	0 (0%)	Late lengthening-phase outcomes not reported

BMP2, bone morphogenic protein 2; LCP, locking compression plate; SUPERhip, systematic utilitarian procedure for extremity reconstruction of the hip

Fig. 3.

Complications by fixation construct and BMP2 use

Violante Júnior et al. reported four complications in 26 patients (15.4%): Two non-unions, one wound dehiscence and one broken plate. No subluxations occurred during the SUPERhip phase. Complications were age-stratified: 4 of 11 patients ≤5 years vs 0 of 15 patients >5 years (p = 0.011). Recurrent varus and persistent delayed ossification were not reported as separate outcomes. Notably, fixation construct in the AACD São Paulo cohort was supply-constrained: 20 of 26 patients (77%) received a 120° locking compression plate (LCP) rather than the canonical 130° blade plate (used in only three patients), with the authors explicitly attributing this to availability of materials in the Brazilian public health system.²⁶ Bone morphogenic protein 2 was not used in any case.

Risk of Bias

Both included cohorts are single-centre retrospective case series, conferring inherent risk of selection and reporting bias. Three convergent risk-of-bias signals are notable. First, neither cohort reports MPFA (Paley's own published framework specifying the dual NSA + MPFA target for proximal femoral correction); this omission is shared by all comparator literature reviewed and represents an empirical finding from the synthesis.²⁷ Second, both cohorts rely on antero-posterior (AP) radiograph assessment without routine cross-sectional imaging, a methodology shown by Tschurl et al. to underestimate posterior acetabular deficiency.^28,29 Third, both cohorts originate from centres methodologically affiliated with the Paley Institute network through training, collaboration or co-authorship; while patient independence is confirmed, methodological independence cannot be assumed.

Discussion

Principal Findings

The central caveat of this synthesis must be stated at the outset: Only two cohort studies (n = 2) met the inclusion criteria, and every observation below should be read within that constraint. The principal contribution of this review is accordingly less a pooled effect estimate than a structured account of what the published evidence does, and does not yet, establish. This systematic review identified two peer-reviewed cohort studies meeting the inclusion criteria for the SUPERhip procedure in Paley type Ib and type II CFD: Paley et al. (n = 106 procedures) and Violante Júnior et al. (n = 26 patients).^14,26 Outcome reporting was structurally asymmetric, precluding meta-analysis: Paley reports complications stratified by technique era but no radiographic indices, while Violante Júnior et al. report radiographic indices and range of motion but limited complication data. The most clinically actionable within-cohort signal in the synthesis is the Paley demonstration that fixed-angle fixation combined with intra-osseous BMP2 reduces recurrent varus from 53 to 7% and delayed ossification from 53 to 4% in primary procedures. The most clinically relevant external-validity finding is that no peer-reviewed cohort outcomes specific to Paley type II (subtypes IIa or SUPERhip-eligible IIb) currently exist. The published evidence base is concentrated within the Paley Institute methodological lineage, with Violante Júnior et al. representing a within-network supply-constrained adaptation rather than independent external validation.

Comparison with the Historical Lengthening-era Literature

The clinical motivation for pre-lengthening Hip reconstruction is established by historical lengthening cohorts in which subluxation rates were substantial. Eidelman et al. reported a 36% subluxation rate in their Paley type Ib subset; Bowen et al. reported acetabular and femoral indices that thresholded the radiographic criteria still in widespread use today (NSA > 120°, AI < 25° and CEA > 20°); Saldanha et al. (cited via the Sheffield protocol description) reported 11 of 47 subluxations during lengthening at the same institution that subsequently introduced standardised pre-lengthening reconstruction; and Shahcheraghi et al. reported a 17.9% (7/39) instability rate in a mixed Aitken-classified cohort that included patients with prior SUPERhip preparation.^8,9,30–32 Against this background, the Sheffield 2025 report of 0 subluxations during subsequent lengthening in 23 patients who had received combined bony and soft-tissue Hip stabilisation represents the strongest single-cohort evidence in support of the principle that pre-lengthening Hip reconstruction reduces during-lengthening instability. Figure 4 displays these comparator rates.³⁰

Fig. 4.

Hip subluxation rates during femoral lengthening

Comparison with Alternative Reconstructive Approaches

Alternative reconstructive pathways exist for CFD patients in whom biological lengthening is not pursued or is contraindicated. Rotationplasty (van Nes procedure) and Syme amputation followed by prosthetic fitting remain the principal ablative options, particularly for Paley type III and type IIc CFD.^33,34 Within the biological-reconstruction pathway, two non-canonical SUPERhip variants warrant comparison. Tschurl et al. reported a Poznań cohort of 33 type Ia CFD patients (20 of whom underwent SUPERhip), constituting the first independent non-Paley-network SUPERhip cohort published, with 21% late Hip instability identified at a mean of 637 days after external fixator removal.²⁸ The Sheffield protocol described by Dhital et al. represents the most thoroughgoing protocol divergence in the literature, reporting a combined bony and soft-tissue reconstruction in which the iliac shortening is replaced by an abductor periosteal slide without iliac resection, sartorius release is added as a standard component, a three-incision approach replaces the canonical single-incision approach, fixation is by Coventry screw plate plus tension band wiring, and the postoperative NSA target is ≥120° (per Bowen et al.) rather than 130°.^28,35

Protocol-fidelity Divergence

Protocol fidelity was assessed across five cohorts on eight canonical technical axes. Three observations follow. First, the synthesis cohorts (Paley et al. and Violante Júnior et al.) sit close-to-canonical practice, with three divergent axes each – including, for Violante, a supply-constrained substitution of the 120° LCP for the canonical 130° blade plate. Second, two extra-network cohorts now exist (Tschurl et al. and Dhital et al.), bracketing the protocol-fidelity range that surgeons outside the Paley Institute network adopt: Tschurl is close to canonical with three divergent axes (NSA target, modified Dega pelvic osteotomy³⁶ with posterior reorientation and BMP2 omission); Sheffield is far divergent with seven divergent axes. Third, the only canonical SUPERhip element on which both extra-network cohorts converge is BMP2 – Sheffield uses it selectively in later years, while Tschurl omits it. The divergence pattern indicates that the abductor slide via iliac shortening, the single-incision approach and the 130° NSA target are the principal points of contention when surgeons outside the Paley network adapt the protocol to their local context.

Type Ia Adjacent Literature

Although Paley type Ia CFD is outside the synthesis scope, three recent peer-reviewed type Ia SUPERhip cohorts inform the discussion. Tschurl et al. (Poznań, n = 20 SUPERhip, 22 lengthenings) reported 0% subluxation during lengthening but 21% late Hip instability at mean of 637 days post-fixator removal (range: 127–1447 days), with coxa vara before lengthening [NSA < 120°; odds ratio (OR) = 10, p < 0.05] and abnormal antetorsion (OR = 6, p = 0.099) as the principal risk factors.²⁸ Critically, computed tomography (CT) in the five available instability cases showed posterior acetabular deficiency that was not visible on AP radiograph (CT posterior AI: 28.3° vs AP-radiograph AI: 19.8°, p < 0.01). Sheffield 2025 – although a mixed-type cohort (16 type Ia, three type Ib, three type IIa and one type IIb) – provides the principal extra-network outcome data, with NSA improving from 89.3° to 119.5° (p < 0.0001), AI decreasing from 31.2° to 17.1° (p = 0.0003), postoperative CEA of 25.9° (preoperative not measurable in patients aged <3 years) and 0/23 subluxations during subsequent lengthening.³⁰ Simpson-White et al. (2013) reported a 19-year follow-up of King's procedure in a Sheffield type IIa case.³⁷ The Tschurl et al.'s finding that Hip morphology appearing normal on AP radiograph at the end of lengthening did not preclude late instability, and that the failure mode was posterior acetabular and visible only on CT, provides a methodologically important caution for cohorts (including both synthesis cohorts) that rely on AP radiograph alone.

Type II Evidence Gap

No peer-reviewed cohort outcomes specific to Paley type II (subtypes IIa or SUPERhip-eligible IIb) currently exist. Paley explicitly excluded type II from its analysis; Violante Júnior et al. report a type Ib cohort only; Sheffield 2025 includes four type II patients embedded in its 23-patient mixed cohort but does not present subtype-stratified outcomes.^14,26,30 The absence of peer-reviewed type-II-specific outcomes is a clinically significant evidence gap, given that type IIa and SUPERhip-eligible type IIb CFD are recognised indications for the procedure and that surgical decision-making for these subtypes currently relies on extrapolation from type Ib data and on personal communication or unpublished case series. This gap should be addressed by future cohort studies that report type II outcomes either as a stratified subset within type Ib/II cohorts or as dedicated type-II-specific case series.

Methodological Observations

Three methodological observations from this synthesis warrant attention in future research. First, the absence of MPFA reporting across all cohorts examined – synthesis cohorts and comparator cohorts alike – is striking given that MPFA is the second of Paley's canonical dual-target indices for proximal femoral correction.²⁷ Standardised radiographic reporting of NSA paired with MPFA, using the dual-target framework Paley himself published, would substantially improve cohort comparability. Second, the during-lengthening/late-post-lengthening endpoint distinction is poorly handled in the existing literature. The Sheffield 0/23 subluxation finding applies to the during-lengthening endpoint only; mean follow-up beyond fixator removal is not reported separately.³⁰ Tschurl et al. demonstrate that 21% of type Ia CFD patients develop late instability at a mean of 637 days post-fixator removal – an endpoint that conventional 6-month minimum follow-up (Paley et al.) and 3-year minimum follow-up (Violante Júnior et al.) protocols may underdetect.²⁸ Future cohorts should report subluxation and dislocation rates separately for these two endpoints. Third, the AP-radiograph reliance shared by all synthesis and comparator cohorts may systematically miss posterior acetabular deficiency identified on CT; selective CT or magnetic resonance imaging (MRI) in cases with abnormal antetorsion or coxa vara before lengthening is supported by Tschurl et al.'s evidence.²⁸

Implications for Clinical Practice and Research

Five implications follow from this synthesis. First, the Paley data provide a within-cohort signal, derived from a single primary dataset rather than generalisable external evidence, consistent with adding fixed-angle fixation and intra-osseous BMP2 to the canonical SUPERhip protocol for type Ib₂/Ib₃ cases; the era confound in the Paley design (calendar-time-correlated technique evolution) further limits clean attribution to BMP2 alone, although it does not undermine the directional signal. Second, no peer-reviewed type-II-specific cohort outcomes exist, and surgeons treating type IIa or SUPERhip-eligible type IIb CFD should be aware that current decision-making relies on extrapolation. Third, future cohort studies should adopt standardised radiographic reporting (NSA paired with MPFA) and should report subluxation rates separately for during-lengthening and late-post-lengthening endpoints. Fourth, the empirical evidence from Tschurl et al. supports the addition of preoperative cross-sectional imaging in cases with abnormal antetorsion or coxa vara before lengthening, given the demonstrated risk of posterior acetabular deficiency that is not visible on an AP radiograph.²⁸ Fifth, the substantial protocol-fidelity divergence demonstrated by the Sheffield cohort and the close-to-canonical adaptation by the Poznań cohort together establish that extra-network SUPERhip implementations are feasible and produce clinically acceptable outcomes; future work should compare specific protocol elements (notably the abductor slide via iliac shortening, the single-incision approach and the 130° NSA target) against modified alternatives in adequately powered prospective designs.^28,30

Limitations

This review is limited by the small number of included studies (n = 2), reflecting the rarity of the underlying condition and the concentration of CFD reconstructive practice in a small number of specialist centres. The two included studies are single-centre retrospective case series with the inherent biases that designation entails. Outcome reporting heterogeneity precluded meta-analysis. Patient independence between the two synthesis cohorts has been confirmed, but methodological independence cannot be: Both cohorts originate from centres within the Paley Institute methodological lineage, and the supply-constrained variants reported in the work by Violante Júnior et al. are an adaptation of canonical Paley practice rather than independent external validation.

Conclusion

The SUPERhip procedure achieves substantial radiographic correction of proximal femoral and acetabular pathoanatomy in Paley type Ib CFD. A within-cohort signal from the originating institution is consistent with adding fixed-angle fixation and intra-osseous BMP2 to the canonical protocol to reduce recurrent varus and persistent delayed ossification, but, resting on a single primary dataset, it requires independent external validation before it can be regarded as generalisable. Synthesised from only two eligible cohorts, the principal contribution of this review is to delineate the gaps in the present evidence base: It remains concentrated within a single methodological lineage, reports outcomes asymmetrically, reports MPFA in no cohort and contains no peer-reviewed type-II-specific cohort outcomes. Standardised radiographic reporting (NSA paired with MPFA), separation of during-lengthening from late-post-lengthening endpoints, dedicated type II cohort studies and methodologically independent external cohorts are the priorities for future research.

Clinical Significance

Hip joint reconstruction before femoral lengthening is supported by the empirical comparator literature for both type Ib and type Ia CFD. Within type Ib, and based on within-cohort data from a single principal dataset, the canonical SUPERhip protocol with fixed-angle fixation and BMP2 is currently the best-evidenced approach; a within-network supply-constrained variant (e.g., 120° LCP substituted for the 130° blade plate) achieved comparable radiographic correction and acceptable complication rates and may be appropriate where the canonical material is unavailable. Late Hip instability is a recognised post-lengthening risk for type Ia CFD and should be specifically counselled to families and tracked in long-term follow-up.

Declarations

Ethical Approval

No ethical approval is needed, as a systematic review uses already published data.

Data Availability Declaration

All data can be sourced from the cited literature. The protocol of this systematic review (SR) is public and published on PROSPERO (CRD420261386450).

Artificial Intelligence (AI) Disclosure

During the preparation of this work, the authors used Claude (Anthropic) for language editing and prose smoothing. The authors reviewed and edited the content as needed and take full responsibility for the content of the publication.

Acknowledgement

The authors thank James Fernandes of the Sheffield Children's NHS Foundation Trust for his support and for allowing us to integrate his in-press data.

Authors' Contributions

ND: Conceptualisation, methodology and writing (review and editing, equal). JAA: Formal analysis (lead), writing (original draft, supporting) and writing (review and editing, equal). DT: Writing (original draft, lead) and writing (review and editing, equal).

Orcid

Jakob A Adolf https://orcid.org/0009-0006-0385-3940