Table V.

Selected studies reporting on muscle damage following different approaches to the hip

Author, year	Approach	Type of surgery	Modality	n (hips)	Reported muscle trauma
Lüdemann et al., [32]	Anterior	THA	MRI	32	Comparison of CSA and degree of fatty infiltration pre and post-operative; decreased CSA of the tensor fasciae latae muscle and increased CSA of the sartorius muscle post-operatively; increased degree of fatty infiltration of the tensor fasciae latae and gluteus minimus muscles post-operatively.
Bremer et al., [1]	Anterior versus transgluteal lateral	THA	MRI	50	Using the anterior approach, tears of the gluteus medius and minimus muscles, peritrochanteric bursa fluid, and atrophy of gluteus medius and minimus muscles were less pronounced or frequent.
Meneghini et al., [29]	Anterior versus posterior	THA	Cadaver	12	Using the anterior approach, less damage occurred to the gluteus minimus muscle or tendon; damage to the tensor fasciae latae or indirect head of the rectus femoris muscle occurred only using the anterior approach; the piriformis and conjoined tendon was detached intentionally in all hips with a posterior approach and were damaged in 50% of hips with a anterior approach; damage to the gluteus medius muscle was comparable.
Unis et al., [8]	Modified Watson-Jones	THA	MRI	26	Following a modified Watson-Jones approach, atrophy or fatty infiltration of the tensor fasciae latae was present in 62 or 42%, respectively.
Müller et al., [2]	Anterolateral versus direct lateral	THA	MRI	44	Using the direct lateral approach, the gluteus medius showed increased fatty infiltration and the tensor fasciae latae an increased CSA.
Vasilakis et al., [33]	Anterolateral versus modified Watson-Jones	THA	MRI	37	No difference in fatty infiltration for the gluteus medius and tensor fasciae latae muscles was found.
Pfirrmann et al., [27]	Transgluteal lateral	THA	MRI	64	Comparing patients with and without trochanteric pain following lateral transgluteal THA; abductor tendon defects and gluteus minimus and medius defects are more common in symptomatic patients.
Pellicci et al., [30]	Posterior	THA	MRI	36	Defects of the piriformis tendon in 43%, conjoined tendon in 57% and the quadratus femoris in 3%.
Khan et al., (28)	Posterior versus modified posterior	THA	MRI	20	Comparing fatty infiltration and volume of the piriformis and obturator internus muscles between an approach with piriformis tendon-repair and a piriformis sparing approach; for the approach with piriformis tendon-repair a decreased volume and increased fatty infiltration was found at 3-month follow-up and a comparable volume but increased fatty infiltration at 2-year follow-up for the piriformis muscle; no difference existed for the obturator internus muscle.
Bal et Lowe, [34]	Two-incision versus direct lateral versus posterior	THA	MRI	32	Minimal atrophic changes was found in hips following the two-incision approach, whereas, all hips following the direct lateral or posterior approach showed atrophic changes of gluteus minimus, medius, maximus, tensor fasciae lata, piriformis, or quadratus femoris muscle.
Mardones et al., [35]	Two-incision versus posterior	THA	Cadaver	20	Every two-incision total hip replacement caused measurable damage to the abductors, the external rotators, or both. Damage to the gluteus medius and minimus was substantially greater with the two-incision technique than with the posterior approach.
Van Oldenrijk et al., [36]	Direct lateral, anterior, anterolateral, posterior versus two-incision	THA	Cadaver	25	Four different less-invasive approaches compared with the conventional lateral approach; the less-invasive approaches did not result in less damage to the gluteus medius than the conventional approach; the less-invasive anterior approach has an increased risk of damaging the lateral femoral cutaneous nerve.
Dora et al., [37]	Percutaneous	Antegrade femoral nailing	Cadaver	16	Comparing three different nail entry points; insertion in piriformis fossa results in most damage to muscle and tendons (piriformis and obturator internus).
McConnell et al., [38]	Percutaneous	Antegrade femoral nailing	Cadaver	34	Average disruption of the tendinous portion of the gluteus medius muscle of 27% (range, 15–53%).

THA, total hip arthroplasty; MRI, magnetic resonance imaging; CSA, cross-sectional area.