Restricted accessResearch articleFirst published online 2026
Histopathological characterization of the hip joint capsule: Comparative study of patients with hip osteoarthritis versus patients with femoral neck fracture
We aimed to delineate the histological characteristics of the hip joint’s capsule of patients undergoing hip arthroplasty (HA) for primary osteoarthritis (OA) versus femoral neck fracture (FNF).
Methods:
86 patients were included: 39 with OA and 47 with FNF. A 2×2 cm capsular sample was harvested near the transverse ligament. Sections (4 µm thick) were stained with haematoxylin and eosin. Outcomes included capsular thickness (mm), fibrosis percentage, vascularization grade, inflammatory infiltrate, and cartilaginous metaplasia.
Results:
Inflammatory infiltrates were present in 25.6% of OA cases and 12.8% of FNF (p = 0.127). Superficial degenerative changes were more common in OA (48.7%) than FNF (10.6%) (p < 0.01). Cartilaginous metaplasia was higher in OA (35.9%) versus FNF (6.4%) (p = 0.01). Vascular density showed no significant difference (p = 0.104). Severe fibrosis was more frequent in OA (46.2%) than FNF (8.5%) (p < 0.01). Mean capsular thickness was greater in OA (5 mm; IQR 4.3–7.1) than FNF (3.1 mm; IQR 2–4) (p < 0.01).
Conclusions:
The hip capsule in OA showed greater thickness, fibrosis, and cartilage metaplasia. These structural differences may influence joint stability and could partly explain differing postoperative outcomes between elective THA for OA and urgent THA for FNF.
JohnsonVLHunterDJ.The epidemiology of osteoarthritis. Best Pract Res Clin Rheumatol2014; 28: 5–15.
2.
ChenDShenJZhaoW, et al. Osteoarthritis: toward a comprehensive understanding of pathological mechanism. Bone Res2017; 5: 16044.
3.
AbramoffBCalderaFE.Osteoarthritis: pathology, diagnosis, and treatment options. Med Clin North Am2020; 104: 293–311.
4.
NiggemeyerOSteinhagenJDeuretzbacherG, et al. Amyloid deposition in osteoarthritis of the hip. Arch Orthop Trauma Surg2011; 131: 637–643.
5.
RakhraKSBonuraAANairnR, et al. Is the hip capsule thicker in diseased hips?Bone Joint Res2016; 5: 586–593.
6.
RemstDFGBlaney DavidsonENvan der KraanPM. Unravelling osteoarthritis-related synovial fibrosis: a step closer to solving joint stiffness. Rheumatology (Oxford)2015; 54: 1954–1963.
7.
Lloyd-RobertsGC.The role of capsular changes in osteoarthritis of the hip joint. J Bone Joint Surg Br1953; 35-B: 627–642.
8.
ScanzelloCRGoldringSR.The role of synovitis in osteoarthritis pathogenesis. Bone2012; 51: 249–257.
9.
GalaLClohisyJCBeauléPE.Hip dysplasia in the young adult. J Bone Joint Surg Am2016; 98: 63–73.
10.
SlullitelPACoutuDButtaroMA, et al. Hip preservation surgery and the acetabular fossa. Bone Joint Res2020; 9: 857–869.
11.
DombBGStakeCELindnerD, et al. Arthroscopic capsular plication and labral preservation in borderline hip dysplasia: two-year clinical outcomes of a surgical approach to a challenging problem. Am J Sports Med2013; 41: 2591–2598.
12.
BowmanKFJrFoxJSekiyaJK.A clinically relevant review of hip biomechanics. Arthroscopy2010; 26: 1118–1129.
13.
NgKCGJeffersJRTBeauléPE.Hip joint capsular anatomy, mechanics, and surgical management. J Bone Joint Surg Am2019; 101: 2141–2151.
14.
ElkinsJMStroudNJRudertMJ, et al. The capsule’s contribution to total hip construct stability–a finite element analysis. J Orthop Res2011; 29: 1642–1648.
15.
AbdelMPvon RothPJenningsMT, et al. What safe zone? The vast majority of dislocated THAs are within the Lewinnek Safe Zone for acetabular component position. Clin Orthop Relat Res2016; 474: 386–391.
16.
AströmJBeertemaJ.Reduced risk of hip fracture in the mothers of patients with osteoarthritis of the hip. J Bone Joint Surg Br1992; 74: 270–271.
17.
Aguado-MaestroIPanteliMGarcía-AlonsoM, et al. Hip osteoarthritis as a predictor of the fracture pattern in proximal femur fractures. Injury2017; 48(Suppl. 7): S41–S46.
18.
FranklinJEnglundMIngvarssonT, et al. The association between hip fracture and hip osteoarthritis: a case-control study. BMC Musculoskelet Disord2010; 11: 274.
19.
DequekerJGorisPUytterhoevenR.Osteoporosis and osteoarthritis (osteoarthrosis). Anthropometric distinctions. JAMA1983; 249: 1448–1451.
20.
KazleyJMBanerjeeSAbousayedMM, et al. Classifications in brief: Garden Classification of femoral neck fractures. Clin Orthop Relat Res2018; 476: 441–445.
21.
BusseJGasteigerWTönnisD.[A new method for roentgenologic evaluation of the hip joint–the hip factor]. Arch Orthop Unfallchir1972; 72: 1–9.
22.
TibboMELimbergAKSalibCG, et al. Anti-fibrotic effects of the antihistamine ketotifen in a rabbit model of arthrofibrosis. Bone Joint Res2020; 9: 302–310.
23.
ScanzelloCRMcKeonBSwaimBH, et al. Synovial inflammation in patients undergoing arthroscopic meniscectomy: molecular characterization and relationship to symptoms. Arthritis Rheum2011; 63: 391–400.
24.
KrennVMorawietzLBurmesterGR, et al. Synovitis score: discrimination between chronic low-grade and high-grade synovitis. Histopathology2006; 49: 358–364.
25.
SongCXuXWuY, et al. Study of the mechanism underlying hsa-miR338-3p downregulation to promote fibrosis of the synovial tissue in osteoarthritis patients. Mol Biol Rep2019; 46: 627–637.
26.
LimbergAKTibboMESalibCG, et al. Reduction of arthrofibrosis utilizing a collagen membrane drug-eluting scaffold with celecoxib and subcutaneous injections with ketotifen. J Orthop Res2020; 38: 2474–2483.
27.
KallioE.Skin arthroplasty of the hip joint and corresponding alloplastic methods in the light of a clinical study. Acta Orthop Scand Suppl1958; 30: 1–99.
28.
KettunenKO.Cartilaginous metaplasia of connective tissue in clinical skin arthroplasty. Acta Orthop Scand1959; 28: 190–197.
29.
CouttsRDAmielDHarwoodFL, et al. Characterization of arthroplasty tissue after 14 years post-cup arthroplasty: a morphological and biochemical assessment. J Orthop Res1984; 2: 425–431.
30.
KamelMFornasierVLPetersW.Cartilaginous metaplasia in the capsule of a Dacron-backed silicone gel breast prosthesis. Ann Plast Surg1999; 42: 202–206.
31.
ZhangKde SaDYuH, et al. Hip capsular thickness correlates with range of motion limitations in femoroacetabular impingement. Knee Surg Sports Traumatol Arthrosc2018; 26: 3178–3187.
32.
ShawCWarwickHNguyenKH, et al. Correlation of hip capsule morphology with patient symptoms from femoroacetabular impingement. J Orthop Res2021; 39: 590–596.
33.
TurnerEHGMarkhardtBKCotterEJ, et al. Patients with generalized joint hypermobility have thinner superior hip capsules and greater hip internal rotation on physical examination. Arthrosc Sports Med Rehabil2022; 4: e1417–e1427.
34.
QinCDHelfrichMMFitzDW, et al. The Lawrence D. Dorr Surgical Techniques & Technologies Award: differences in postoperative outcomes between total hip arthroplasty for fracture vs osteoarthritis. J Arthroplasty2017; 32: S3–S7.
35.
SchairerWWLaneJMHalseyDA, et al. The Frank Stinchfield Award: Total hip arthroplasty for femoral neck fracture is not a typical DRG 470: a propensity-matched cohort study. Clin Orthop Relat Res2017; 475: 353–360.
36.
WandJSHillIDReeveJ.Coxarthrosis and femoral neck fracture. Clin Orthop Relat Res1992; 88–94.
37.
BiyaniASimisonAJKlenermanL.Intertrochanteric fractures of the femur and osteoarthritis of the ipsilateral hip. Acta Orthop Belg1995; 61: 83–91.
38.
CalderazziFGroppiGRicottaA, et al. Does hip osteoarthritis have a protective effect against proximal femoral fractures? A retrospective study. Hip Int2014; 24: 231–236.
39.
WolfOStrömHMilbrinkJ, et al. Differences in hip bone mineral density may explain the hip fracture pattern in osteoarthritic hips. Acta Orthop2009; 80: 308–313.
40.
DretakisEKSteriopoulosKAKontakisGM, et al. Cervical hip fractures do not occur in arthrotic joints. A clinicoradiographic study of 256 patients. Acta Orthop Scand1998; 69: 384–386.
41.
MalutaTTosoGNegriS, et al. Correlation between hip osteoarthritis and proximal femoral fracture site: could it be protective for intracapsular neck fractures? A retrospective study on 320 cases. Osteoporos Int2019; 30: 1591–1596.
42.
BayramBLimbergAKSalibCG, et al. Molecular pathology of human knee arthrofibrosis defined by RNA sequencing. Genomics2020; 112: 2703–2712.
43.
PearleADScanzelloCRGeorgeS, et al. Elevated high-sensitivity C-reactive protein levels are associated with local inflammatory findings in patients with osteoarthritis. Osteoarthritis Cartilage2007; 15: 516–523.
44.
BenitoMJVealeDJFitzGeraldO, et al. Synovial tissue inflammation in early and late osteoarthritis. Ann Rheum Dis2005; 64: 1263–1267.
