Vol 10 | Issue 2 | July-December 2024 | page: 44-47 | Pavan Patil, Rajeev Joshi, Sahil Sanghavi, Mahavir Dugad, Darshan Sonawane, Ashok Shyam, Parag Sancheti

https://doi.org/10.13107/jmt.2024.v10.i02.252

Author: Pavan Patil [1], Rajeev Joshi [1], Sahil Sanghavi [1], Mahavir Dugad [1], Darshan Sonawane [1], Ashok Shyam [1], Parag Sancheti [1]

[1] Department of Orthopaedics, Sancheti Institute of Orthopaedics and Rehabilitation, Pune, Maharashtra, India.

Address of Correspondence
Dr. Pavan Patil,
Department of Orthopaedics, Sancheti Institute of Orthopaedics and Rehabilitation, Pune, Maharashtra, India.
E-mail: drpavan010@gmail.com

Abstract

Background: Restoring femoral offset and limb length is essential for pain relief, stable gait and patient satisfaction after primary total hip replacement. Small deviations can alter abductor mechanics and affect function.
Methods: We prospectively studied 150 patients undergoing primary total hip replacement at a single centre from October 2019 to December 2021. Preoperative templating used standardized AP pelvic radiographs. Leg-length discrepancy was measured by the Woolson inter-teardrop method and global offset was calculated from acetabular and femoral measurements. Clinical outcomes were recorded before surgery and at postoperative intervals. Data were analysed using appropriate statistical tests for repeated measures.
Results: Most patients achieved postoperative limb-length and global-offset differences within five millimeters of the contralateral hip. Pain scores fell and functional scores rose consistently over the first postoperative year. Radiographic review showed stable components and a low complication rate.
Conclusion: Careful radiographic templating combined with attentive intraoperative technique can reliably restore offset and limb length within clinically acceptable limits in routine primary total hip replacement. This reconstruction is therefore associated with meaningful early gains in pain relief, mobility and quality of life; longer follow-up will clarify effects on implant survivorship.
Keywords: Total hip replacement, Femoral offset, Leg-length discrepancy, Templating, Patient-reported outcomes, Radiographic measurement

Introduction:

Total hip replacement is one of orthopedics’ most successful procedures and has transformed the lives of many patients with end-stage hip disease. To achieve predictable relief of pain and recovery of function, surgeons must do more than insert well-fixed implants — they must also restore the hip’s native geometry so that muscles and soft tissues work efficiently. Restoring femoral offset and the correct limb length are central to rebuilding a balanced hip: femoral offset determines the abductor lever arm and thus affects muscle strength and joint reaction forces, while leg-length inequality can cause limp, back pain and dissatisfaction if not corrected. [1–5]
Small changes in offset or length can influence abductor tension, gait mechanics and patient perception. Decreasing offset tends to shorten the abductor lever arm and can reduce muscular efficiency; increasing offset beyond what is necessary may over-tension soft tissues and cause discomfort. Likewise, even modest leg-length differences can be noticeable to patients, and larger discrepancies frequently lead to symptomatic complaints. Preoperative templating on standardized radiographs and careful intraoperative assessment are practical tools to reduce these risks in routine practice. This study used those methods to examine whether restoration of offset and limb length correlates with better patient-reported outcomes and to evaluate the reliability of plain radiographic measurement in a clinical setting. [1–5]

Review of literature
Earlier biomechanical and clinical work has repeatedly highlighted the importance of femoral offset and limb length in hip arthroplasty. Several studies showed that changes in offset alter abductor mechanics and can translate into measurable differences in gait and muscle strength. Restoration of offset has been associated with improved abductor leverage and, in some series, lower rates of component-related problems. [6–9]
Radiographic templating on AP pelvis films is the standard approach in most centres because it is accessible and practical, though it has recognized limitations: plain radiographs can underestimate true three-dimensional offset when compared with CT and are sensitive to pelvic rotation and magnification. Where available, 3-D planning provides greater accuracy, but for routine primary cases standardized radiography combined with careful technique offers a pragmatic balance of accuracy and convenience. [6–10]
Clinical thresholds vary between studies: some reports suggest that length differences up to about 10–20 mm may be tolerated by many patients, while others note that discrepancies above roughly 5–10 mm are more likely to affect gait symmetry or satisfaction. Gait-analysis studies indicate that combined deviations of length and offset correlate with altered kinematics; however, the effect on patient-reported outcome measures is often modest when deviations are small. Taken together, the literature supports aiming to restore offset and limb length as closely as practical while recognizing that small deviations within accepted limits frequently have limited clinical impact. [11–13]

Materials and Methods
This single-centre prospective study included 150 consecutive patients who underwent primary total hip replacement from October 2019 to December 2021. Exclusion criteria were congenital hip deformity, bilateral symptomatic disease at presentation, ankylosed hips and arthroplasty for acute trauma. Baseline demographic data and preoperative scores (Harris Hip Score, WOMAC, Oxford Hip Score, VAS and SF-36) were recorded.
Preoperative templating was performed on standardized AP pelvic radiographs. Leg length was measured by the inter-teardrop to lesser trochanter distance (Woolson method) and global offset as the sum of acetabular and femoral offsets on the AP film. To reduce radiographic error we used consistent patient positioning and magnification markers. Surgeries were performed predominantly via a posterolateral approach with templated osteotomy and trial reductions to confirm stability and soft-tissue balance. Modular head/neck options were used when intraoperative adjustments were needed.
Postoperative radiographs and clinical evaluations were performed at 6 weeks, 6 months and 12 months. Radiographic assessment included component position and signs of loosening or osteolysis. Continuous variables are presented as medians (IQR) and categorical data as counts (percentages). Repeated measures were analysed with linear mixed-effects models to account for within-patient correlations over time.

Results
The results reflect a large, generally healthy cohort of 151 patients (median age 51 years, IQR 39–60; 68% male). Median hospital stay was 5 days; median height 160 cm, weight 67 kg and BMI 25.7. Comorbidities were present in 58% (hypertension 32%, diabetes 13%, hypothyroid 7%, ischemic heart disease 5%). Radiographically, median global offset on the operated side was 7.24 cm (IQR 6.95–7.68) versus 7.24 cm (IQR 6.83–7.93) on the contralateral side (p = 0.52), while median leg-length measured 4.51 cm (IQR 4.06–4.99) operated versus 4.55 cm (IQR 3.90–4.89) contralateral (p < 0.001), indicating only small, clinically acceptable differences for most patients. Patient-reported outcomes improved markedly from baseline to 12 months: Harris Hip Score median 34 → 84, WOMAC 62 → 12, Oxford Hip Score 15 → 42, VAS pain 8 → 1, and SF-36 physical function 27 → 80 (all trends p < 0.0001). At one year median pain was low (VAS 1, IQR 1–2) and quality-of-life domains rose substantially. Early complications were uncommon: there were no cups with progressive migration at final review and only a few osteolytic lesions. Patients with offset or length differences within small thresholds (approximately ≤5 mm) experienced functional gains comparable to the whole cohort; larger discrepancies were rare and therefore made subgroup analysis limited.

Discussion
This series confirms that careful preoperative templating and attentive intraoperative technique can restore hip geometry — offset and limb length — within clinically acceptable margins for most patients undergoing primary THR. The findings echo prior biomechanical and clinical studies that link accurate offset reconstruction to improved abductor mechanics and suggest that restoring anatomy supports better objective and subjective outcomes. [14–16]
The literature describes a range of acceptable thresholds for offset and length discrepancies. While some degree of variation may be tolerated, deviations above commonly cited thresholds are more likely to alter gait kinematics and provoke symptoms. Where offset cannot be restored by a standard implant configuration, modular components or high-offset stems provide practical intraoperative options to fine-tune reconstruction. Radiographic templating on AP films remains a pragmatic method for routine cases; although CT-based planning is more precise, it is not necessary for every primary THR and is best reserved for complex anatomy or dysplastic hips. [16–18]
Several larger cohort and systematic reviews report similar conclusions: small deviations from native offset or limb length often have little effect on PROMs, but under-correction of offset and larger leg-length inequality are associated with worse functional measures and gait abnormalities in some studies. Surgeons should therefore aim for accurate restoration while recognizing that small residual differences are common and frequently clinically acceptable. [19–20]

Conclusion
In this cohort of 150 primary THR patients, restoration of limb length and global offset to within small, clinically acceptable margins was achieved in the majority. These patients showed consistent improvement in pain, function and health-related quality of life at one year. Standardized radiographic templating and intraoperative verification provide an effective, pragmatic approach to biomechanical reconstruction in routine primary THR. Three-dimensional planning remains valuable in selected complex cases.

References

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Institute Where Research was Conducted: Department of Orthopaedics, Sancheti Institute of Orthopaedics and Rehabilitation, Shivajinagar, Pune, Maharashtra, India.
India.
University Affiliation: Maharashtra University Of Health Sciences (MUHS), Nashik,
Maharashtra, India
Year of Acceptance of Thesis: 2019

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