Traumatic rupture of the inferior rectus muscle: clinical presentation and surgical management

Abstract

Traumatic inferior rectus (IR) muscle rupture can occur following orbital trauma or intraoperatively during strabismus surgery. Isolated case reports have been published in the literature.1Yip CC Jain A McCann JD Demer JL. Inferior rectus muscle transection: a cause of diplopia after non-penetrating orbital trauma.Graefes Archive Clinical Exp Ophthalmol. 2006; 244: 1698-1700Crossref PubMed Scopus (9) Google Scholar, 2Paysse EA Saunders RA Coats DK. Surgical management of strabismus after rupture of the inferior rectus muscle.J AAPOS. 2000; 4: 164-167Abstract Full Text Full Text PDF PubMed Scopus (31) Google Scholar, 3Tomasetti P Metzler P Jacobsen C. Isolated inferior rectus muscle rupture after blunt orbital trauma.J Surg Case Rep. 2013; 2013: rjt076https://doi.org/10.1093/jscr/rjt076Crossref Google Scholar, 4Leonardo Landó TdO Jomar Cleison de Rezende. Inferior rectus muscle rupture due to orbital trauma.Rev Bras Oftalmol. 2017; 76: 40-42Google Scholar, 5Sloan B McNab AA. Inferior rectus rupture following blowout fracture.Aust N Z J Ophthalmol. 1998; 26: 171-173Crossref PubMed Scopus (22) Google Scholar, 6Godeiro KD Pinto AG Souza Filho JP Petrilli AM Nakanami CR. Traumatic tear of the inferior rectus muscle treated with inferior oblique anterior transposition.Int Ophthalmol. 2005; 26: 185-189Crossref PubMed Scopus (5) Google Scholar, 7Cuiqin Du KZ Treatment of rupture of the inferior rectus muscle.Chin J Ophthalmol. 1993; 29: 40-41Google Scholar In traumatic injuries of the extraocular muscles, the inferior and medial rectus muscles are most commonly involved, which is thought to be due to the closer proximity of their insertions to the corneoscleral limbus.2Paysse EA Saunders RA Coats DK. Surgical management of strabismus after rupture of the inferior rectus muscle.J AAPOS. 2000; 4: 164-167Abstract Full Text Full Text PDF PubMed Scopus (31) Google Scholar They are also anatomically more exposed during protective reflexes such as blinking and Bell's phenomenon, making them more susceptible to trauma.8Tynan D Dunn H Roberts T. Complete inferior rectus transection following blunt trauma: a case report and novel approach to surgical repair.Ophthalmic Plast Reconstr Surg. 2019; 35: e69-e72Crossref PubMed Scopus (1) Google Scholar, 9Huerva V Mateo AJ Espinet R. Isolated medial rectus muscle rupture after a traffic accident.Strabismus. 2008; 16: 33-37Crossref PubMed Scopus (12) Google Scholar, 10Nitta K Kashima T Miura F Hiroe T Akiyama H Kishi S. A case of blunt trauma of the eyeball associated with an inferior oblique muscle and an inferior rectus muscle rupture.Ophthalmic Plast Reconstr Surg. 2016; 32: e121-e123Crossref PubMed Scopus (1) Google Scholar In addition, the medial and inferior orbital walls are more commonly fractured, making the adjacent muscles more prone to injury.11Hong S Lee HK Lee JB Han SH. Recession-resection combined with intraoperative botulinum toxin A chemodenervation for exotropia following subtotal ruptured of medial rectus muscle.Graefes Arch Clin Exp Ophthalmol. 2007; 245: 167-169Crossref PubMed Scopus (8) Google Scholar The IR muscle functions as the main depressor as well as a secondary adductor of the eye.12Kowal L Wutthiphan S McKelvie P. The snapped inferior rectus.Aust N Z J Ophthalmol. 1998; 26: 29-35Crossref PubMed Scopus (18) Google Scholar Because of this, the diplopia related to rupture of the IR muscle causes significant functional disruption in visual tasks related to reading, walking, descending stairs, and driving. The affected eye develops an incomitant hypertropia in primary position, which increases in downgaze. Most patients have to adopt a chin-down head position to avoid the resulting vertical diplopia.13Cherfan CG Traboulsi EI. Slipped, severed, torn and lost extraocular muscles.Can J Ophthalmol. 2011; 46: 501-509Abstract Full Text Full Text PDF PubMed Scopus (14) Google Scholar Various surgical approaches have been suggested that are aimed at retrieving and strengthening the injured IR muscle or providing muscle force from adjacent extraocular muscles.14Sari A Adigüzel U Ismi T. An unexpected outcome of blunt ocular trauma: rupture of three muscles.Strabismus. 2009; 17: 95-97Crossref PubMed Scopus (10) Google Scholar Ideally, the ruptured muscle is retrieved, and the distal and proximal muscle ends are sutured together.12Kowal L Wutthiphan S McKelvie P. The snapped inferior rectus.Aust N Z J Ophthalmol. 1998; 26: 29-35Crossref PubMed Scopus (18) Google Scholar However, the ruptured muscle cannot always be retrieved, in which case generally the antagonist muscle can be recessed or a complete or modified tendon transposition procedure of the adjacent muscles is performed.12Kowal L Wutthiphan S McKelvie P. The snapped inferior rectus.Aust N Z J Ophthalmol. 1998; 26: 29-35Crossref PubMed Scopus (18) Google Scholar,14Sari A Adigüzel U Ismi T. An unexpected outcome of blunt ocular trauma: rupture of three muscles.Strabismus. 2009; 17: 95-97Crossref PubMed Scopus (10) Google Scholar,15Aguirre-Aquino BI Riemann CD Lewis H Traboulsi EI. Anterior transposition of the inferior oblique muscle as the initial treatment of a snapped inferior rectus muscle.J AAPOS. 2001; 5: 52-54Abstract Full Text Full Text PDF PubMed Scopus (19) Google Scholar Most commonly, a partial or complete total transposition of the rectus muscles with or without concomitant recession of the ipsilateral antagonist is used in patients with ruptured rectus muscles.16MacEwen CJ Lee JP Fells P. Aetiology and management of the “detached” rectus muscle.Br J Ophthalmol. 1992; 76: 131-136Crossref PubMed Scopus (55) Google Scholar Injection of botulinum toxin A has also been used as an adjunct to surgery to minimize the number of muscles operated on and thus the risk of anterior segment ischemia.15Aguirre-Aquino BI Riemann CD Lewis H Traboulsi EI. Anterior transposition of the inferior oblique muscle as the initial treatment of a snapped inferior rectus muscle.J AAPOS. 2001; 5: 52-54Abstract Full Text Full Text PDF PubMed Scopus (19) Google Scholar For anatomic reasons, a ruptured IR muscle is more easily retrieved than a ruptured medial rectus muscle. This is likely due to its attachments to an adjacent oblique muscle unlike the medial rectus.17Scott AB. The Faden operation: mechanical effects.Am Orthopt J. 1977; 27: 44-47Crossref PubMed Google Scholar This paper retrospectively reviews the clinical presentation and surgical management of 9 patients with traumatic rupture of the inferior rectus muscle. A retrospective case review was undertaken for 9 patients seen by 1 strabismus surgeon (M.F.) between 2010 and 2019. The following data were collected from the clinical records of each patient: patient demographics (age and sex), mechanism of injury, associated injuries and time to surgery, number and type of surgical interventions undertaken, preoperative and postoperative measurements of alignment, and motility. A surgical outcome was considered excellent if postoperative primary position and downgaze alignment was restored to 0 prism diopters (PD) of hypertropia and infraduction returned to normal (0= full rotation into downgaze; –1 = 75% of normal rotation; –2= 50% of normal; –3 = 25% of normal; –4 = no rotation beyond the horizontal plane). The outcome was considered good if primary position alignment was less than 4 PD of hypertropia, downgaze alignment was less than 13 PD of hypertropia, and infraduction was 0 to –2 and poor if primary position hypertropia was 4 PD or greater hypertropia, downgaze alignment was greater than 13 PD or greater of hypertropia, and infraduction limitation was greater than –2. Patient demographics and injury details are presented in Table 1. The median patient age was 37 years (range, 22–82 years), and the majority were male (6 of 9). IR muscle rupture was caused by trauma in 7 cases and by an iatrogenic intraoperative event in 2 patients. The former was often caused by a small, sharp object such as a hook, high heel shoe, candlestick, or thumb (Table 1). In traumatic cases, IR muscle rupture was often associated with conjunctival laceration (6 of 9). Other associated injuries included lower eyelid or facial lacerations (2 of 9), orbital floor fracture (2 of 9), and retinal injury (1 of 9). In the first iatrogenic case (patient 5), the rupture occurred during attempted repair of a muscle that had been lacerated initially by trauma from a hook. The second iatrogenic rupture (patient 3) occurred in a patient with significant muscle restriction due to thyroid orbitopathy. All patients complained of diplopia in primary position and downgaze and adopted a chin-down compensatory head position to minimize the diplopia.Table 1Patient demographics and the cause and nature of injuryCaseAge (y)SexMechanism of injuryAssociated findingsTime to surgery (d)122FHigh heel shoe ODConjunctival laceration1232MHigh heel shoe ODOrbital floor fracture, retinal injury5356FStrabismus surgery OD intraoperative ruptureThyroid-related orbitopathy39437MHook injury ODConjunctival and lower lid lacerations12563FHook injury OD intraoperative rupture during repair of lacerated inferior rectusConjunctival laceration95682MCandlestick ODConjunctival lacerations3727MThumb injury OSConjunctival lacerations14839MIron bar ODConjunctival laceration270923MPunch with fist OSOrbital floor fracture, facial lacerationsNot operated Open table in a new tab Pre- and postoperative examination findings and surgical details are summarized in Table 2, and images from all 9 cases are shown in Figure 1(A,B). Eight patients underwent surgical repair of the ruptured IR muscle. The median time from injury to primary repair surgery was 13 days (range, 1–270 days). A secondary surgery was done in 4 cases and a tertiary surgery in 1. In the final patient, spontaneous and near-total improvement of ocular alignment and ductions was observed at follow-up 2 months after the initial injury, negating the need for surgery (Fig. 2). Among patients requiring surgery, preoperatively, the mean (± SD) hypertropia in primary gaze was 16.6 ± 6.2 PD, and the mean limitation in infraduction of the affected eye was –3.0 ± 0.5 PD. Postoperatively, mean hypertropia improved to 0.8 ± 1.4 PD with a mean infraduction limitation of –1.0 ± 0.7. Seven of the 9 patients had no primary position postoperative diplopia. However, 7 of the patients continued to have diplopia in more extreme positions of downgaze. Two patients had an excellent postoperative outcome (1 requiring a secondary surgery), and the remainder of outcomes (6 or 8) were classified as fair.Table 2Alignment, motility, and surgical dataPatientNo. of surgeriesPrimary ADV (mm)Secondary recession/resection (mm)TertiaryHT (PD) preoperatively PP/DGHT (PD) Postoperatively PP/DGDepression (–1 to –4) preoperativelyDepression (–1 to –4) postoperatively12Explore RIR + ADV*Not recorded.RIR resection LIR PFS + recession—17/350/0–3–123Explore RIR + ADV*Not recorded.RSR recessionRIR resectionLLR recessionLMR resection20/403/†Spontaneous resolution by 2 months after injury.–3–231Explore RIR+ ADV (13 to >6.5 mm)——30/700/10–3–1.542Explore RIR + ADV (13 to >10 mm)RIR ADV (11 to >6 mm)RSR recession—10/400/10–3052Explore RIR + ADV (16 to >8 mm)——12/253/10–2–161Explore RIR + ADV (16 to >10 mm)——14/350/0–4071Explore LIR + ADV (18 to >11)——16/350/10–3–1.581Explore RIR + ADV (15 to >9 mm)LIR recession—14/350/12–3–190None——20/350/0*Not recorded.–30*HT = hypertropia; PD = prism diopters; PP = primary position; DG = downgaze; RIR = right inferior rectus; ADV = advancement (millimeters posterior to limbus); LIR = left inferior rectus; PFS = posterior fixation suture Not recorded.† Spontaneous resolution by 2 months after injury. Open table in a new tab Fig. 2Patient 9. Initial computed tomography scans (preoperative repair of orbital floor fracture): (A) coronal view; (B) sagittal view; (C, D) follow-up scans after orbital floor fracture repair.View Large Image Figure ViewerDownload Hi-res image Download (PPT) HT = hypertropia; PD = prism diopters; PP = primary position; DG = downgaze; RIR = right inferior rectus; ADV = advancement (millimeters posterior to limbus); LIR = left inferior rectus; PFS = posterior fixation suture Primary surgical management involved retrieving the proximal end of the ruptured IR muscle, followed by advancement and reinsertion. Most often muscle rupture occurred at or posterior to the tendon–muscle junction. In most cases, the distal muscle stump was dissected off the sclera, and the proximal end of the ruptured muscle was advanced anteriorly on the sclera toward the original insertion site using hang-back sutures, as depicted in Figure 3. On average, the proximal end was found 15 mm posterior to the limbus and advanced to a position 9 mm from the limbus. In 2 cases (patients 2 and 4), secondary surgical management to improve infraduction of the affected eye involved resection or advancement of the previously ruptured IR muscle and recession of the antagonist superior rectus muscle. However, in 2 patients (patients 1 and 8), improving infraduction of the affected eye was achieved by recessing the IR muscle of the contralateral (unaffected) eye. Patient 1, who had 17 PD of right hypertropia, also received a posterior fixation suture on the left IR muscle known as the Faden operation.17Scott AB. The Faden operation: mechanical effects.Am Orthopt J. 1977; 27: 44-47Crossref PubMed Google Scholar,18Harcourt B. Faden operation (posterior fixation sutures).Eye (Lond). 1988; 2: 36-40Crossref PubMed Scopus (19) Google Scholar Isolated rupture of the IR muscle is a rare event. The medial rectus muscle is the most frequently injured extraocular muscle, followed by the IR muscle.19Bloom PA Harrad R. Medial rectus rupture: a rare condition with an unusual presentation.J R Soc Med. 1993; 86: 112-113PubMed Google Scholar,20Chen J Kang Y Deng D Shen T Yan J. Isolated total rupture of extraocular muscles.Medicine (Baltimore). 2015; 94: e1351Crossref PubMed Scopus (9) Google Scholar The reason for this remains unclear, but it can be related to the proximity of the insertion site to the limbus, with the medial and inferior rectus muscles inserting more anteriorly than the lateral or superior rectus.2Paysse EA Saunders RA Coats DK. Surgical management of strabismus after rupture of the inferior rectus muscle.J AAPOS. 2000; 4: 164-167Abstract Full Text Full Text PDF PubMed Scopus (31) Google Scholar In addition, the medial and inferior rectus muscles are more susceptible to trauma because they are more exposed during blinking and other protective reflexes.8Tynan D Dunn H Roberts T. Complete inferior rectus transection following blunt trauma: a case report and novel approach to surgical repair.Ophthalmic Plast Reconstr Surg. 2019; 35: e69-e72Crossref PubMed Scopus (1) Google Scholar, 9Huerva V Mateo AJ Espinet R. Isolated medial rectus muscle rupture after a traffic accident.Strabismus. 2008; 16: 33-37Crossref PubMed Scopus (12) Google Scholar, 10Nitta K Kashima T Miura F Hiroe T Akiyama H Kishi S. A case of blunt trauma of the eyeball associated with an inferior oblique muscle and an inferior rectus muscle rupture.Ophthalmic Plast Reconstr Surg. 2016; 32: e121-e123Crossref PubMed Scopus (1) Google Scholar The medial and inferior orbital walls are also more commonly injured, resulting in more frequent injuries to the adjacent extraocular muscles.11Hong S Lee HK Lee JB Han SH. Recession-resection combined with intraoperative botulinum toxin A chemodenervation for exotropia following subtotal ruptured of medial rectus muscle.Graefes Arch Clin Exp Ophthalmol. 2007; 245: 167-169Crossref PubMed Scopus (8) Google Scholar Similar to previous reports, the etiology of IR muscle rupture in this study is a mix of trauma and intraoperative rupture.1Yip CC Jain A McCann JD Demer JL. Inferior rectus muscle transection: a cause of diplopia after non-penetrating orbital trauma.Graefes Archive Clinical Exp Ophthalmol. 2006; 244: 1698-1700Crossref PubMed Scopus (9) Google Scholar,3Tomasetti P Metzler P Jacobsen C. Isolated inferior rectus muscle rupture after blunt orbital trauma.J Surg Case Rep. 2013; 2013: rjt076https://doi.org/10.1093/jscr/rjt076Crossref Google Scholar,21Kashima T Akiyama H Kishi S. Longitudinal tear of the inferior rectus muscle in orbital floor fracture.Orbit. 2012; 31: 171-173Crossref PubMed Scopus (5) Google Scholar,22Richards R. Ocular motility disturbances following trauma.Adv Ophthalmic Plast Reconstr Surg. 1987; 7: 133-147PubMed Google Scholar Typically, rupture of extraocular muscles occurs at the muscle–tendon junction or at the mid-belly of the muscle.13Cherfan CG Traboulsi EI. Slipped, severed, torn and lost extraocular muscles.Can J Ophthalmol. 2011; 46: 501-509Abstract Full Text Full Text PDF PubMed Scopus (14) Google Scholar,15Aguirre-Aquino BI Riemann CD Lewis H Traboulsi EI. Anterior transposition of the inferior oblique muscle as the initial treatment of a snapped inferior rectus muscle.J AAPOS. 2001; 5: 52-54Abstract Full Text Full Text PDF PubMed Scopus (19) Google Scholar Of note, patient 3 had thyroid-related ophthalmopathy, and the intraoperative rupture may have been related to excessive traction on a very tight muscle to gain access to the muscle. Other identified risk factors for intraocular rupture of a muscle include extraocular muscle pathology.13Cherfan CG Traboulsi EI. Slipped, severed, torn and lost extraocular muscles.Can J Ophthalmol. 2011; 46: 501-509Abstract Full Text Full Text PDF PubMed Scopus (14) Google Scholar,23Dunbar JA Lueder GT. Intraoperative dehiscence of a rectus muscle: report of two cases.J AAPOS. 1997; 1: 175-177Abstract Full Text PDF PubMed Scopus (11) Google Scholar Muscles ruptured intraoperatively or due to trauma are more easily retrieved because of the preserved fascial attachments to the globe and incomplete rupture of fibres.17Scott AB. The Faden operation: mechanical effects.Am Orthopt J. 1977; 27: 44-47Crossref PubMed Google Scholar Because the medial rectus is the only muscle not attached to the globe via an adjacent oblique muscle, it can freely retract into the orbit and thus is more difficult to retrieve than other muscles.17Scott AB. The Faden operation: mechanical effects.Am Orthopt J. 1977; 27: 44-47Crossref PubMed Google Scholar By contrast, other rectus muscles that rupture can be retrieved by tracing attachments to adjacent oblique muscles.17Scott AB. The Faden operation: mechanical effects.Am Orthopt J. 1977; 27: 44-47Crossref PubMed Google Scholar Numerous surgical approaches have been described in the treatment of ruptured extraocular muscles, and the optimal choice depends on the nature of the injury.13Cherfan CG Traboulsi EI. Slipped, severed, torn and lost extraocular muscles.Can J Ophthalmol. 2011; 46: 501-509Abstract Full Text Full Text PDF PubMed Scopus (14) Google Scholar When the proximal and distal ends of the muscle can be identified, a direct end-to-end anastomosis can be done or insertion of the posterior segment of the muscle onto the sclera.13Cherfan CG Traboulsi EI. Slipped, severed, torn and lost extraocular muscles.Can J Ophthalmol. 2011; 46: 501-509Abstract Full Text Full Text PDF PubMed Scopus (14) Google Scholar Repaired ruptures muscles can lose power, and there can be residual postoperative limitation of motility.11Hong S Lee HK Lee JB Han SH. Recession-resection combined with intraoperative botulinum toxin A chemodenervation for exotropia following subtotal ruptured of medial rectus muscle.Graefes Arch Clin Exp Ophthalmol. 2007; 245: 167-169Crossref PubMed Scopus (8) Google Scholar,13Cherfan CG Traboulsi EI. Slipped, severed, torn and lost extraocular muscles.Can J Ophthalmol. 2011; 46: 501-509Abstract Full Text Full Text PDF PubMed Scopus (14) Google Scholar When the proximal muscle end cannot be retrieved, transposition procedures are necessary to improve ocular alignment. In this study, initial surgical management involved retrieving the proximal end of the ruptured IR muscle and reinserting the anterior end of this muscle segment to the globe. The distal part of the muscle that was still attached to the insertion site was excised. In other studies, if the anterior portion of the muscle that was still attached to the globe was not felt to be viable, the retrieved muscle was directly sutured to the sclera.21Kashima T Akiyama H Kishi S. Longitudinal tear of the inferior rectus muscle in orbital floor fracture.Orbit. 2012; 31: 171-173Crossref PubMed Scopus (5) Google Scholar Adjustable sutures were used during the surgeries in this series to improve postoperative alignment control. The secondary operations were undertaken because of residual ocular misalignment due to contracture of the superior rectus or persistent limitation of infraduction. Multiple approaches can be undertaken to further strengthen the IR muscle. Strategies employed in this series to further strengthen the injured muscle included resection at the time of a second procedure of the ipsilateral IR muscle and further advancement of the ipsilateral IR muscle. Further strategies included weakening of the contralateral IR muscle (patients 1 and 8) and weakening of the ipsilateral antagonist (patients 2 and 4). Care was taken to avoid anterior segment ischemia resulting from operating on 3 or more extraocular muscles. Interestingly, patient 9 in this series improved spontaneously. This patient demonstrated a complete tear of the IR muscle on computed tomography (CT) scan prior to undergoing open reduction and internal fixation of an orbital floor fracture. It is suspected that the severed inferior rectus was unconsciously repositioned during fixation of the orbital floor because, as per the operative report, there was no reanastomosis of the IR muscle performed at the time of surgery. The exact interval during which a muscle should be recovered to restore some functionality remains inconclusive.24Minguini N Ikeda KS de Carvalho KM. Traumatic avulsion of extraocular muscles: case reports.Arq Bras Oftalmol. 2013; 76: 124-125Crossref PubMed Scopus (2) Google Scholar When a rupture is suspected, some suggest immediate consideration of surgical exploration to avoid the sequelae of diplopia.9Huerva V Mateo AJ Espinet R. Isolated medial rectus muscle rupture after a traffic accident.Strabismus. 2008; 16: 33-37Crossref PubMed Scopus (12) Google Scholar,20Chen J Kang Y Deng D Shen T Yan J. Isolated total rupture of extraocular muscles.Medicine (Baltimore). 2015; 94: e1351Crossref PubMed Scopus (9) Google Scholar Muscles ruptured intraoperatively should be retrieved immediately for the best postoperative outcomes.17Scott AB. The Faden operation: mechanical effects.Am Orthopt J. 1977; 27: 44-47Crossref PubMed Google Scholar On the other hand, in the absence of an associated orbital wall fracture, surgery may be delayed for more than 6 months to allow time for spontaneous improvement.21Kashima T Akiyama H Kishi S. Longitudinal tear of the inferior rectus muscle in orbital floor fracture.Orbit. 2012; 31: 171-173Crossref PubMed Scopus (5) Google Scholar In our study, time to intervention to retrieve the ruptured IR muscle did not seem to affect surgical outcomes (Table 2): patients 3 and 5 received corrective surgeries 39 and 95 days, respectively, after the injury, and their results were satisfactory. Hence we recommend that initial muscle retrieval should always be attempted regardless of the time to intervention. While age has been identified as a predisposing factor for extraocular muscle rupture, our study saw a diverse age range among patients depending on mechanism of injury.8Tynan D Dunn H Roberts T. Complete inferior rectus transection following blunt trauma: a case report and novel approach to surgical repair.Ophthalmic Plast Reconstr Surg. 2019; 35: e69-e72Crossref PubMed Scopus (1) Google Scholar Traumatic inferior rectus (IR) muscle rupture is a rare event that can occur following orbital trauma or intraoperatively during strabismus surgery. In this case series, the proximal end of the ruptured muscle was retrieved and reattached to the globe. Successfully re-establishing the normal anatomic position of the injured muscle is an effective way to restore function. Reconnecting the proximal segment is quite feasible and avoids using the devitalized distal position in an anastomosis. The remaining 3 rectus muscles are initially preserved and can be selected for secondary surgeries with less risk of anterior segment ischemia. Most patients had good postoperative outcomes regardless of the time to intervention; thus, an initial attempt at retrieval of the ruptured muscle should occur regardless of the time delay to surgery.