Phocomelia

                                   Dr. KS Dhillon

Introduction

Phocomelia (fig 1) is a rare congenital disorder. It is defined by the absence of intermediate segments of the extremity. In children with phocomelia, the hands or feet are directly attached to the trunk. Phocomelia is a teratogenic side effect of the drug thalidomide. This drug was first marketed to treat anxiety and morning sickness. There were claims that the drug was safe during pregnancy. It was however removed from the market in the 1960s when doctors noted an association with phocomelia. About 40% of patients affected by the teratogenic effects of thalidomide die near the time of birth. These congenital disabilities had a profound political and social impact on drug regulation and proof of safety (1,2).

Fig 1.

Etiology

Phocomelia is the most notable side effect of thalidomide. In the last 30 years, there have been several cases of phocomelia associated with thalidomide use. Today however the cause of most cases is undetermined. Despite strict regulation worldwide, there have been several cases of phocomelia attributed to thalidomide. Underdeveloped countries and those that are endemic with leprosy where thalidomide remains in use, still report cases of defects caused by thalidomide exposures in pregnancy. In more developed countries with strict regulations, there has been a dramatic decrease in the incidence of phocomelia within the general population (3,4).

Besides the teratogenicity of thalidomide, researchers have hypothesized that phocomelia is associated with anomalous origins of the subclavian artery. This results in a disrupted vascular supply to intermediate limb segments (5,6).

Epidemiology

Bermejo-Sanchez et al (1) examined 22,740,933 live births to study the incidence and presentation of phocomelia to assess the prevalence of true phocomelia. According to reports true phocomelia occurs in 0.62 live births per every 100,000 births. About half (53.2%) of the cases displayed isolated phocomelia, 36.9% had additional major congenital abnormalities, and 9.9% of cases correlated with a clinical syndrome. 

According to the data one limb was involved in 55.9% of the cases, while in 40.2% of cases, two limbs were involved. Of the 141 cases, only four cases had involvement of all four limbs. When single upper limb deficiencies are compared, the left side is more commonly affected (64.9%) than the right side. When two limbs are involved, the upper limbs are involved 58.5% of the time compared to the lower limbs (1,7). 

Pathophysiology

When the extremity develops, the apical ectodermal ridge forms at the most distal end of the limb bud. This apical ectodermal ridge, through its interaction with the underlying progress zone mesoderm, determines the appropriate longitudinal growth of the extremity and differentiation of the limb bud's distal and proximal structures. Cell death due to apoptosis from any cause such as drug toxicity or vascular insufficiency that interrupts this relationship between the apical ectodermal ridge and the progress zone can produce phocomelia (8).

History and Physical Examination

Whenever phocomelia is identified in a newborn, given its correlation with thalidomide, doctors should inquire about medications taken during early pregnancy. Children with phocomelia should undergo a thorough physical examination since one study reported that 36.9% of phocomelia cases have additional major malformations, with 9.9% of cases being attributable to various syndromes (1).

Evaluation

In children when phocomelia is identified, the doctors should complete a thorough search for other associated abnormalities. Other defects are present in approximately half of the patients with this limb anomaly. Doctors should examine the musculoskeletal system, including the heart, vertebrae, and intestines, as dysfunction in these organ systems appears most frequently in conjunction with phocomelia (1).

Management

In the management of children born with phocomelia, it is important to look for other associated abnormalities, especially of the intestines and heart, and address them promptly. Gastroenterologists and pediatric cardiologists should examine the child and recommend a treatment plan for abnormalities encountered.

For patients with hypoplastic limbs, prosthetics may be of some value. Many without concomitant pathology can function quite well. Families of children with severely hypoplastic extremities should work with therapists to meet the unique needs of their children. Caring for a disabled child can be traumatic for some people. Hence, physicians should have a low threshold to recommend mental counseling services to assist in coping mechanisms that may be needed by both the child and the parents.

Differential Diagnosis

Bermejo-Sanchez et al (1) reported that 9.9% of cases of phocomelia are associated with different syndromes. They are listed here in order of decreasing prevalence:

1. Roberts Syndrome: A rare autosomal recessive disorder caused by a mutation in the ESCO2 gene that manifests with severe limb malformations and craniofacial defects (9).

2. Thrombocytopenia with radial aplasia (TAR): A rare autosomal recessive disorder related to the RBM8A gene that presents with thrombocytopenia and limb radial deficiency (10).

3. Syndrome of severe limb defects, vertebral hypersegmentation, and mirror polydactyly: An autosomal recessive disorder resulting in severe limb hypoplasia with polydactyly and hypersegmentation of the spine (11).

Prognosis

In a review study by Bermejo-Sánchez, there were 85 live births to every 24 stillbirths for children with phocomelia. In patients with isolated phocomelia, there were 57 live births to every eight stillbirths (1).

Complications

Children with phocomelia have a higher stillbirth rate as compared to the general population. Children with severe limb hypoplasia may face problems with mobility and activities of daily life. 

Patient Education

The incidence of thalidomide-induced limb hypoplasia has significantly reduced due to increased drug regulatory practices across the world. Thalidomide can be used for the treatment of insomnia, anxiety, and even leprosy. It is important to understand the risks of thalidomide exposure during pregnancy for any woman taking the medication. Patients and doctors should understand the deleterious effects of thalidomide when taken in early pregnancy.

Conclusion

In the regulatory practices of pharmacology, phocomelia and the thalidomide controversy were critical steps forward. The most important responsibility of the healthcare community with regards to phocomelia, is the prevention of prescribing unsafe medications that can cause limb truncation. This can be done through careful prescribing practices and patient education.

For patients born with limb hypoplasia, including phocomelia, an interdisciplinary team of specialists needs to examine the patient. This team can screen patients for associated abnormalities that may be fatal since half of the patients with phocomelia and amelia have associated defects. Many related abnormalities of the vertebrae, heart, or other vital organs may be life-threatening. These anomalies should be addressed promptly by the physicians. If surgical intervention is required, the dedicated OR team must be well-versed with the operative plan and work efficiently to optimize patient outcomes.

A prosthetist and therapist can help a developing child with disabilities to function at a higher level. Families of these disabled children are often under tremendous financial and emotional strain. Hence, appropriate mental health counseling and social work may be necessary to care for the patient and their families.

References

1. Bermejo-Sánchez E, Cuevas L, Amar E, Bianca S, Bianchi F, Botto LD, Canfield MA, Castilla EE, Clementi M, Cocchi G, Landau D, Leoncini E, Li Z, Lowry RB, Mastroiacovo P, Mutchinick OM, Rissmann A, Ritvanen A, Scarano G, Siffel C, Szabova E, Martínez-Frías ML. Phocomelia: a worldwide descriptive epidemiologic study in a large series of cases from the International Clearinghouse for Birth Defects Surveillance and Research, and overview of the literature. Am J Med Genet C Semin Med Genet. 2011 Nov 15;157C(4):305-20. 

2. Ridings JE. The thalidomide disaster, lessons from the past. Methods Mol Biol. 2013;947:575-86.

3. Castilla EE, Ashton-Prolla P, Barreda-Mejia E, Brunoni D, Cavalcanti DP, Correa-Neto J, Delgadillo JL, Dutra MG, Felix T, Giraldo A, Juarez N, Lopez-Camelo JS, Nazer J, Orioli IM, Paz JE, Pessoto MA, Pina-Neto JM, Quadrelli R, Rittler M, Rueda S, Saltos M, Sánchez O, Schüler L. Thalidomide, a current teratogen in South America. Teratology. 1996 Dec;54(6):273-7.

4. Schuler-Faccini L, Soares RC, de Sousa AC, Maximino C, Luna E, Schwartz IV, Waldman C, Castilla EE. New cases of thalidomide embryopathy in Brazil. Birth Defects Res A Clin Mol Teratol. 2007 Sep;79(9):671-2. 

5. van der Horst RL, Gotsman MS. Anomalous origin of the subclavian artery associated with phocomelia. S Afr Med J. 1971 Dec 18;45(48):1397-9. 

6. Bavinck JN, Weaver DD. Subclavian artery supply disruption sequence: hypothesis of a vascular etiology for Poland, Klippel-Feil, and Möbius anomalies. Am J Med Genet. 1986 Apr;23(4):903-18.

7. Källén B, Rahmani TM, Winberg J. Infants with congenital limb reduction registered in the Swedish Register of Congenital Malformations. Teratology. 1984 Feb;29(1):73-85.

8. Knobloch J, Rüther U. Shedding light on an old mystery: thalidomide suppresses survival pathways to induce limb defects. Cell Cycle. 2008 May 01;7(9):1121-7.

9. Ismail S, Essawi M, Sedky N, Hassan H, Fayez A, Helmy N, Shehab M, Farouk D, Elruby M, Otaify G, Eldarsh A, Hosny L, Gaber K, Aboul-Ezz EHA, Ramzy MI, Mehrez MI, Hassib NF, Elhadidi SMA, Aglan MS, Temtamy SA. ROBERTS SYNDROME: CLINICAL AND CYTOGENETIC STUDIES IN 8 EGYPTIAN PATIENTS AND MOLECULAR STUDIES IN 4 PATIENTS WITH GENOTYPE/PHENOTYPE CORRELATION. Genet Couns. 2016;27(3):305-323. 

10. Al-Qattan MM. The Pathogenesis of Radial Ray Deficiency in Thrombocytopenia-Absent Radius (TAR) Syndrome. J Coll Physicians Surg Pak. 2016 Nov;26(11):912-916. 

11. Urioste M, Lorda-Sánchez I, Blanco M, Burón E, Aparicio P, Martínez-Frías ML. Severe congenital limb deficiencies, vertebral hypersegmentation, absent thymus and mirror polydactyly: a defect expression of a developmental control gene? Hum Genet. 1996 Feb;97(2):214-7.

 

            Medial Ulnar Collateral Ligament Injury

                              Dr. KS Dhillon

Introduction

The medial ulnar collateral ligament (MUCL), also referred to as the medial collateral ligament (MCL), ulnar collateral ligament (UCL), and anterior bundle (AB) is the primary restraint to valgus instability of the elbow (1-5). The MUCL is one of three ligaments that comprise the “medial ulnar collateral ligament complex” of the elbow. The posterior bundle (PB) and transverse ligament (TL) are the other two (Fig 1). 

Fig 1.

The MUCL is the primary stabilizer of the elbow during valgus stress, followed by the radial head and dynamic stabilizers of the elbow such as the flexor-pronator muscle mass (6-10). The MUCL is composed of two separate bands (posterior and anterior) that provide reciprocal function with the posterior band tight in flexion, and the anterior band tight in extension. 

The MUCL is commonly injured in overhead-throwing athletes when a valgus moment is placed on the elbow during the early acceleration and late cocking phases (11-15). Incompetence or rupture of the ligament leads to valgus instability of the elbow which has varying clinical presentations. Patients may complain of instability, most however will report pain, reduced accuracy, and decreased velocity. Clinically significant pathology usually requires surgery. Appropriate graft positioning at both the humeral origin and the ulnar insertion is necessary when doing ligament reconstruction. A thorough understanding of the native anatomy of the MUCL facilitates the surgeon’s ability to restore stability and function effectively.

Morrey and An (10) in 1985 were the first to publish the quantitative analysis of the medial ulnar collateral ligament complex. They dissected 10 fresh frozen cadavers and described the dimensions of the AB and PB at various degrees of elbow flexion. Since then, multiple studies have assessed the anatomy and biomechanics of the AB (2,3,6,16,17). In the past general consensus held that the AB inserts solely and directly onto the sublime tubercle. Recent studies however have shown that the AB insertion is in fact broader, tapered, and significantly larger in terms of surface area. 

Anatomy

The MUCL (AB) is the primary restraint to valgus instability of the elbow (1-5). The PB is a soft tissue stabilizer of the elbow with greatest contributions during flexion (17). It is generally believed that the TL does not provide a significant contribution to elbow stability (10). A recent study however has revealed a direct insertion of the TL onto the AB that may potentially play a role in elbow stability (18). The AB, in particular, is the primary stabilizer of the elbow in valgus stress, with the radial head and dynamic stabilizers of the medial elbow also contributing (6-10). It originates on the anterioinferior surface of the medial epicondyle and goes on to insert on the sublime tubercle of the ulna (Fig 1).

Origin

Surface area and footprint center: The origin of the AB is posterior to the elbow’s axis of rotation. It is on the anterior, inferior, and lateral aspect of the medial epicondyle (10). The surface area of the humeral origin has been widely variable. Dugas et al (19) carried out a study in 13 fresh frozen cadavers utilizing a three-dimensional (3-D) electromagnetic tracking and digitalizing device and showed that the AB origin was round with a mean surface area of 45.5 mm2 (range of 25.9-59.4 mm2). A recent study by Camp et al (18) found a mean origin surface area of 32.3 mm2. In contrast to these two studies, Frangiamore et al (20) also studied 10 fresh frozen cadaver specimens and found the measurement to be notably smaller at 17.0 mm2 (range of 14.9-19.1 mm2). It is possible that due to differences in measurement techniques, these studies demonstrated variable results. 

Frangiamore et al (20) and Dugas et al (19) described the center of the ligament origin in different terms. This is of clinical importance when determining the location of humeral tunnel placement during MUCL reconstruction surgery. Dugas et al (19) described the center of the origin in an area on a flat surface anterior and inferior to the medial epicondyle. The mean distance they measured was 13.4 mm from the center of the medial epicondyle to the center of the origin. Camp et al (18) found a similar mean distance of 11.7 mm. Frangiamore et al (20) described this measurement in terms of two separate measurements. They reported the center of the origin to be located, on average, 8.5 mm distal (inferior) and 7.8 mm lateral (anterior) to the medial epicondyle. 

Insertion

Surface area and footprint center: The ulnar footprint of the AB inserts solely onto the sublime tubercle. It serves as the anatomical landmark for surgical repairs and reconstructions. In one early report, the mean AB insertional surface area was 66.4 mm2 (20).

Recently some authors have described the AB insertion as a longer, distally tapered area that follows the ulnar ridge. Dugas et al (19) reported that the surface area of this broader insertion has a mean surface area of 127.8 mm2. They found that the length of the ulnar footprint measured an average of 29.2 mm. Other authors have found similar lengths of tapered insertion with means of 30.2 mm and 29.2 mm (21,22). Camp et al (18) found a tapered insertion with a mean surface area of 187.6 mm2 and an ulnar footprint length averaging 29.7 mm.

Since the footprint center of a broader tapered insertion may not occur in the location previously assumed at the apex of the sublime tubercle, the optimal position of the ulnar tunnel in reconstructive surgery may still need to be elucidated. The clinical relevance of the broader tapered ulnar insertion described in studies by Camp et al (18) and Dugas et al (19) requires further investigation.

A study of 10 cadaveric specimens by Camp et al (18) has shown the mean proximal insertional width to be 9.4 mm which is greater than previously reported (18). This discrepancy in widths leaves room for further investigation. 

Overall ligament dimensions

Length: The AB is the longest ligament of the medial elbow. It spans the inferior aspect of the medial epicondyle to the sublime tubercle and extends distally along the ulnar ridge. The reported average length of AB is between 21.1 mm and 31.4 mm (2,9,10,17,20,23). These lengths were measured from the origin's center to the sublime tubercle's center, based on a direct insertion onto the sublime tubercle without a distal extension. In contrast, more recent reports measured the length from the center of the humeral origin to the most distal point of tapered insertion. They reported mean lengths of 53.9 mm (21) and 51.7 mm (22). The difference in length measured between a non-tapered sublime insertion and a tapered insertion calls for further study to evaluate native AB anatomy. The appropriate length of the ligament component has important implications for ligament reconstruction.

It is important to remember that the AB is not an isometric soft tissue stabilizer. It changes in length throughout flexion. The length of AB changes by 18%, between 2.8 mm and 4.8 mm as the elbow moves from extension to flexion (6,10,24). The dynamic length of the AB must also be kept in mind during reconstruction procedures.

Width: The width of the AB varies. It increases distally to its greatest width at the sublime tubercle before tapering to a point as it inserts distally along the ulnar ridge. Generally, there has been limited variability in widths of the AB, ranging from 4.0 to 7.6 mm (2,5,10,17,25,26).

Surface area: The reported mean surface area of the AB is between 108 mm2 to 135 mm2 (2,10) in studies that did not consider the full distal footprint. Given that Dugas et al (19) have shown the tapered ulnar footprint alone to have a mean surface area of 127.8 mm2, the overall surface area of the ligament will undoubtedly be significantly greater than previously assumed. A more recent study published by Camp et al (18) has shown the mean surface area of the entire AB to be 324.2 mm2.

Biomechanics

Valgus instability

When a valgus stress is applied the MUCL provides a vital contribution to the stability of the elbow. Morrey and An in a fresh frozen cadaveric model showed that with an intact radial head, the MUCL contributes 31% and 54% to valgus restraint at 0° and 90° of flexion, respectively (1). In this study,  varying valgus loads from 0 to 3 nm were applied at 0° and 90° of flexion in 4 fresh frozen cadavers. There was 3° of valgus laxity in full extension and 2° of laxity in flexion with the maximum force applied. There are several studies that have performed similar biomechanical testing at various degrees of flexion and various amounts of force (2,3,5,6,10,25,27). The amount of valgus laxity varies from 2° to 8° when the MUCL is intact.

Callaway et al (3) showed valgus laxity of 3.6° under a 2nm load compared to an unloaded elbow at 30° and 90° of flexion. Safran et al (5) studied 12 cadaveric specimens with a 2Nm load applied at 30 degrees of elbow flexion, and showed a mean alignment of 10.7° of valgus with a neutral forearm rotation. This study did not determine the inherent valgus alignment in an unloaded elbow. Hence it is not possible to compare these studies. With an intact MUCL and a 2 nm load applied, the amount of valgus laxity is generally greatest at 30° of flexion (5).

The effect of transecting the AB on elbow stability has been studied by several authors. In cadaveric models when the AB is disrupted, the amount of valgus instability increases until the point at which secondary osseous stabilizers such as the radial head provide stability. Callaway et al (3) demonstrated the greatest instability at 90° of flexion in the presence of AB deficiency. The study reported a gain of 1.6, 2.8, 3.2, and 3.0 degrees of valgus motion at 30, 60, 90, and 120 degrees of flexion, respectively compared to the intact state. Mullen et al (28) showed that at 90 degrees of flexion, AB transection increases valgus instability by 150%. Floris et al (25) and Søjbjerg et al (29) showed that the greatest instability occurs at 70 degrees of flexion, with recorded valgus angles of 11.8˚ and 14.2˚. Safran et al (5) produced a maximal gain of 6.3˚of laxity under 2 nm of valgus load with a transected AB at elbow flexion of 50˚. Finally, Morrey et al (4) showed a gain of laxity over baseline ranging from 3.3˚ to 4.8˚ in cadaver specimens at 20 degrees of elbow flexion. An intact AB is vital in maintaining valgus stability of the elbow throughout the flexion range.

Rotational instability

Forearm internal rotation is constrained by the soft tissue stabilizer of the medial elbow. While there is inherent internal rotation of the forearm during flexion, the degree of rotation is limited between 2.8˚-6˚ in an uninjured elbow (4,6,25). Transection of the AB allows internal rotation of the forearm to increase to 18.5˚ at 60˚ of joint flexion (25). A correct understanding of these biomechanics is important in repair and reconstruction since rotatory moment is part of the mechanism of injury.

Tissue strength

The AB is the most frequently injured ligament in overhead throwing athletes, although it has been shown to have the most inherent strength and stiffness (6,17). This shows that significant loads are placed on the medial side of the elbow during the late cocking and early acceleration phase (30,31). In a cadaveric model when each soft tissue stabilizer was evaluated under stress, the AB was found to be the strongest with an average load to failure of 260.9 N (17). During overhead throwing, the elbow experiences 64nm of mean valgus torque and 290N of tensile force on the medial side which is greater than the threshold for failure of 260.9N (30,31). A maximal mean valgus load of 90Nm has been reported (32-34). In a recent study of 81 professional baseball pitchers (MLB and MiLB), over 82000 throws showed a mean valgus torque of 60 nm with individual participant means ranging from 41 nm to 94 nm (35). Hence, it is evident why the AB fails in this subset of athletes based on the load to failure being below the force imparted on the elbow.

Conclusion

The AB of the medial ulnar collateral ligament complex plays a crucial role in elbow stability, especially as a valgus and rotational constraint. The AB originates on the humerus. It inserts onto the sublime tubercle of the ulna. Based on recent studies, the ulnar footprint has a broader insertion that is more tapered and elongated than previously thought. The data regarding the centers of the ulnar and humeral footprints guides proper tunnel placement during reconstructive procedures. 

Although the ligament is quite strong, the amount of force placed across the elbow in elite overhead-throwing athletes routinely exceeds the ligament's average load to failure. Hence it is not surprising why MUCL injuries are so common amongst baseball players and pitchers.

Understanding the native anatomy and biomechanics of the MUCL is clinically important to help understand the pathoanatomy and also to guide surgical techniques when treating MUCL injuries.

References

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2. Alcid JG, Ahmad CS, Lee TQ. Elbow anatomy and structural biomechanics. Clin Sports Med. 2004;23:503–517, vii. doi: 10.1016/j.csm.2004.06.008. 

3. Callaway GH, Field LD, Deng XH, Torzilli PA, O’Brien SJ, Altchek DW, Warren RF. Biomechanical evaluation of the medial collateral ligament of the elbow. J Bone Joint Surg Am. 1997;79:1223–1231. doi: 10.2106/00004623-199708000-00015. 

4. Morrey BF, Tanaka S, An KN. Valgus stability of the elbow. A definition of primary and secondary constraints. Clin Orthop Relat Res. 1991;265:187–195. 

5. Safran M, Ahmad CS, Elattrache NS. Ulnar collateral ligament of the elbow. Arthroscopy. 2005;21:1381–1395. doi: 10.1016/j.arthro.2005.07.001.

6. Bryce CD, Armstrong AD. Anatomy and biomechanics of the elbow. Orthop Clin North Am. 2008;39:141–154, v. doi: 10.1016/j.ocl.2007.12.001. 

7. Cohen MS, Bruno RJ. The collateral ligaments of the elbow: anatomy and clinical correlation. Clin Orthop Relat Res. 2001;383:123–130. doi: 10.1097/00003086-200102000-00014. 

8. Ahmad CS, Park MC, Elattrache NS. Elbow medial ulnar collateral ligament insufficiency alters posteromedial olecranon contact. Am J Sports Med. 2004;32:1607–1612. doi: 10.1177/0363546503263149. 

9. Eygendaal D, Valstar ER, Söjbjerg JO, Rozing PM. Biomechanical evaluation of the elbow using roentgen stereophotogrammetric analysis. Clin Orthop Relat Res. 2002;396:100–105. doi: 10.1097/00003086-200203000-00017. 

10. Morrey BF, An KN. Functional anatomy of the ligaments of the elbow. Clin Orthop Relat Res. 1985;201:84–90.

11. Bruce JR, Andrews JR. Ulnar collateral ligament injuries in the throwing athlete. J Am Acad Orthop Surg. 2014;22:315–325. doi: 10.5435/JAAOS-22-05-315.

12. Jones KJ, Osbahr DC, Schrumpf MA, Dines JS, Altchek DW. Ulnar collateral ligament reconstruction in throwing athletes: a review of current concepts. AAOS exhibit selection. J Bone Joint Surg Am. 2012;94:e49. doi: 10.2106/JBJS.K.01034. [DOI] 

13. Rohrbough JT, Altchek DW, Hyman J, Williams RJ 3rd, Botts JD. Medial collateral ligament reconstruction of the elbow using the docking technique. Am J Sports Med. 2002;30:541–548. doi: 10.1177/03635465020300041401. 

14. Conway JE, Jobe FW, Glousman RE, Pink M. Medial instability of the elbow in throwing athletes. Treatment by repair or reconstruction of the ulnar collateral ligament. J Bone Joint Surg Am. 1992;74:67–83. 

15. Singh H, Osbahr DC, Wickham MQ, Kirkendall DT, Speer KP. Valgus laxity of the ulnar collateral ligament of the elbow in collegiate athletes. Am J Sports Med. 2001;29:558–561. doi: 10.1177/03635465010290050601.

16. O’Driscoll SW, Jaloszynski R, Morrey BF, An KN. Origin of the medial ulnar collateral ligament. J Hand Surg Am. 1992;17:164–168. doi: 10.1016/0363-5023(92)90135-c. [DOI] 

17. Regan WD, Korinek SL, Morrey BF, An KN. Biomechanical study of ligaments around the elbow joint. Clin Orthop Relat Res. 1991;271:170–179.

18. Camp CL, Jahandar H, Sinatro AM, Imhauser CW, Altchek DW, Dines JS. Quantitative Anatomic Analysis of the Medial Ulnar Collateral Ligament Complex of the Elbow. Orthop J Sports Med. 2018;6:2325967118762751. doi: 10.1177/2325967118762751. [DOI] 

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20. Frangiamore SJ, Moatshe G, Kruckeberg BM, Civitarese DM, Muckenhirn KJ, Chahla J, Brady AW, Cinque ME, Oleson ML, Provencher MT, et al. Qualitative and Quantitative Analyses of the Dynamic and Static Stabilizers of the Medial Elbow: An Anatomic Study. Am J Sports Med. 2018;46:687–694. doi: 10.1177/0363546517743749.

21. Farrow LD, Mahoney AJ, Stefancin JJ, Taljanovic MS, Sheppard JE, Schickendantz MS. Quantitative analysis of the medial ulnar collateral ligament ulnar footprint and its relationship to the ulnar sublime tubercle. Am J Sports Med. 2011;39:1936–1941. doi: 10.1177/0363546511406220.

22. Farrow LD, Mahoney AP, Sheppard JE, Schickendantz MS, Taljanovic MS. Sonographic assessment of the medial ulnar collateral ligament distal ulnar attachment. J Ultrasound Med. 2014;33:1485–1490. doi: 10.7863/ultra.33.8.1485. 

23. Beckett KS, McConnell P, Lagopoulos M, Newman RJ. Variations in the normal anatomy of the collateral ligaments of the human elbow joint. J Anat. 2000;197 Pt 3:507–511. doi: 10.1046/j.1469-7580.2000.19730507.x.

24. Armstrong AD, Ferreira LM, Dunning CE, Johnson JA, King GJ. The medial collateral ligament of the elbow is not isometric: an in vitro biomechanical study. Am J Sports Med. 2004;32:85–90. doi: 10.1177/0363546503258886.

25. Floris S, Olsen BS, Dalstra M, Søjbjerg JO, Sneppen O. The medial collateral ligament of the elbow joint: anatomy and kinematics. J Shoulder Elbow Surg. 1998;7:345–351. doi: 10.1016/s1058-2746(98)90021-0.

26. Timmerman LA, Andrews JR. Histology and arthroscopic anatomy of the ulnar collateral ligament of the elbow. Am J Sports Med. 1994;22:667–673. doi: 10.1177/036354659402200515. 

27. Rooker JC, Smith JRA, Amirfeyz R. Anatomy, surgical approaches and biomechanics of the elbow. Orthop Trauma. 2016;30:283–290.

28. Mullen DJ, Goradia VK, Parks BG, Matthews LS. A biomechanical study of stability of the elbow to valgus stress before and after reconstruction of the medial collateral ligament. J Shoulder Elbow Surg. 2002;11:259–264. doi: 10.1067/mse.2002.122622. [DOI] 

29. Søjbjerg JO, Ovesen J, Nielsen S. Experimental elbow instability after transection of the medial collateral ligament. Clin Orthop Relat Res. 1987;218:186–190. 

30. 30.Werner SL, Fleisig GS, Dillman CJ, Andrews JR. Biomechanics of the elbow during baseball pitching. J Orthop Sports Phys Ther. 1993;17:274–278. doi: 10.2519/jospt.1993.17.6.274. [DOI] 

31. Fleisig GS, Andrews JR, Dillman CJ, Escamilla RF. Kinetics of baseball pitching with implications about injury mechanisms. Am J Sports Med. 1995;23:233–239. doi: 10.1177/036354659502300218.

32. Fleisig GS, Kingsley DS, Loftice JW, Dinnen KP, Ranganathan R, Dun S, Escamilla RF, Andrews JR. Kinetic comparison among the fastball, curveball, change-up, and slider in collegiate baseball pitchers. Am J Sports Med. 2006;34:423–430. doi: 10.1177/0363546505280431. 

33. Fleisig GS, Escamilla RF. Biomechanics of the elbow in the throwing athlete. Oper Techn Sport Med. 1996;4:62–68. 

34. Loftice J, Fleisig GS, Zheng N, Andrews JR. Biomechanics of the elbow in sports. Clin Sports Med. 2004;23:519–530, vii-viii. doi: 10.1016/j.csm.2004.06.003. 

35. Camp CL, Tubbs TG, Fleisig GS, Dines JS, Dines DM, Altchek DW, Dowling B. The Relationship of Throwing Arm Mechanics and Elbow Varus Torque: Within-Subject Variation for Professional Baseball Pitchers Across 82,000 Throws. Am J Sports Med. 2017;45:3030–3035. doi: 10.1177/0363546517719047.

 

Osteochondritis Dissecans

                             Dr. KS Dhillon

Introduction

Osteochondritis dissecans (OCD) was first described in 1888 by the German surgeon Franz König (1). Osteochondritis dissecans is also known as an osteochondral lesion. It is not a fully understood process, though it is believed to be multi-factorial in etiology. OCD is an idiopathic condition that can develop from childhood through adult life. The majority of patients present in their teenage years. The severity of these lesions can range from being asymptomatic to mild pain or in advanced cases having symptoms of joint instability and locking. The lesions can progress from stable to fragmentation of the overlying cartilage with the formation of a loose body in the joint space. Eventual early onset osteoarthritic changes of the joint can occur at any level of severity if not diagnosed and adequately treated. Therefore, early recognition and treatment are important to achieve good long-term outcomes.

Etiology

The etiology of osteochondritis dissecans has yet to be fully elucidated. It is believed to be multi-factorial. Postulated etiologies include spontaneous avascular necrosis, genetic predisposition, inflammation, and repetitive microtrauma. Originally it was believed to be related to osseous inflammation, hence the term osteochondritis. Multiple studies have failed to prove inflammation as the underlying cause. Spontaneous osteonecrosis is believed to occur during the maturation of the overlying cartilage during adolescence. At this time, the vascular supply to the subchondral bone moves from a juvenile perichondrial supply to mature supply from the medullary cavity. It is believed that during this transition period, the epiphyseal bone is predisposed to avascular necrosis. A higher prevalence of OCD in young athletes also suggests an etiology of repetitive microtrauma.  These theories have been studied with varying success in coming to a conclusion about the cause of this disease. The most commonly accepted etiology is that of repetitive microtrauma, with or without an inciting event. (2,3).

Epidemiology

The incidence of osteochondritis dissecans is approximately 15 to 29 per 100,000 patients (4). The majority of patients are 10 to 20 years of age although it can occur from childhood through adult life (5). Males are affected twice as often as females (5). There is a higher incidence in young athletes. The knee, particularly the lateral aspect of the medial femoral condyle, is the most affected joint. The elbow (capitellum) and ankle (talus) are also affected to a lesser degree (2,6).

Pathophysiology

Osteochondritis dissecans is an idiopathic focal joint disorder affecting the subchondral bone regardless of the etiology. Fragmentation of a small focus of subchondral bone creates a defect between the osteochondral lesion and the parent bone. This leads to decreased vascularization and osteonecrosis of the fragment. Fragments that are held in place by intact overlying articular cartilage are stable. Progression of the defect to involve the overlying cartilage is possible. This will lead to instability of the fragment. If lesions become unstable, they may displace from the parent site and become a loose body within the joint. In a large percentage of these affected patients, early-onset osteoarthritis occurs due to the altered articular surface caused by the osteochondral lesion.

History and Physical

Discovery and presentation of osteochondral lesions are variable. Patients can be asymptomatic. The lesion may be incidentally detected at imaging. This is true in patients who have been asymptomatic or those who never presented for evaluation but had remote chronic mild pain that resolved without treatment. Other patients present when they have chronic mild pain of the affected joint, with or without an acute injury. Typically these patients present several months to a year after the onset of symptoms. When there is a loose fragment, symptoms are generally more severe, with marked joint pain, swelling, locking, and joint instability (2,3).

Examination shows that these patients may have joint tenderness with painful or decreased range of motion of the involved joint, and swelling or effusion. Other injuries, such as ligamentous injuries and fracture has to be excluded (3).

Evaluation

Imaging plays a key role in the evaluation and treatment of these patients. Routine radiographs of the affected joint are obtained. Radiographs will show an ovoid lucency in the subchondral bone with adjacent sclerotic bone. Occasionally the bony fragment can be seen within the subchondral defect or, if displaced, elsewhere within the joint. Radiographs cannot determine the osseous fragment's stability and underestimate the lesion size. An MRI is usually used to confirm the diagnosis when an abnormality is detected on radiographs. It helps to differentiate a developmental ossification variation from OCD and aids in treatment planning, and helps to determine if the lesion is likely to be stable at the time of arthroscopy.  An MRI is highly sensitive and specific in the evaluation of fragment stability. Therefore, it is recommended for patients in whom stability is a clinical concern.

According to De Smet, the following four signs on MRI are associated with OCD lesion instability (7): 

• A discrete round focus of hyperintense signal deep to the OCD lesion measuring 5 mm or more

• Line of hyperintense signal equal to the fluid at the fragment bone interface measuring 5 mm or more in length

• Focal defect in the overlying cartilage measuring 5 mm or more

• Hyperintense signal equal to the fluid that traverses the articular cartilage and the subchondral bone which extends to the lesion.  

To evaluate for stability these same findings can be applied to any joint with an OCD lesion. These criteria have high specificity and sensitivity in the determination of OCD lesion stability.  MRI arthrography can be useful in difficult cases. Although CT arthrography is not as sensitive, it can be used in the patient when MRI is contraindicated.

MRI is also useful in monitoring treatment of the patients if conservative or surgical treatment is chosen.  The recommended time interval to perform an MRI to evaluate healing depends on the institutional protocol and surgeon. MRI findings that suggest healing following conservative management include: 

• Decrease or resolution in the surrounding bone marrow edema pattern

• A decrease in lesion size

• Decrease or the resolution of the hyperintense T2 signal rim or cyst-like foci

• Ingrowth of bone within the bed of the OCD lesion with osseous bridging.

After surgery, an MRI allows for noninvasive evaluation of the repair of the articular surface and the bone cartilage interface (7).

Treatment

The patient’s age, presentation time, severity of symptoms, and lesion stability will dictate treatment. Several systems to classify the lesions have been developed. The important feature is the degree of overlying cartilage involvement and mobility of the lesion fragment. In stable lesions, conservative management is the treatment of choice. Immobilization is carried out and protected weight-bearing is done for a length of time, depending on which joint is affected. When conservative treatment fails in patients with stable lesions they may be treated with drilling techniques (retroarticular or transarticular drilling). These drilling procedures have shown healing rates and symptom improvement in 92% to 100% of the patients. Transarticular drilling has slightly higher success rates. When lesions are displaced or unstable, surgical intervention is necessary. The drilling is typically performed arthroscopically. The knee lesions most often require surgery. Fifty-eight percent of procedures for OCD lesions are performed on the knee. There are various modalities and techniques that exist, such as debridement, fixation, microfracture, and cartilage grafting/transplantation. In situ fixation of lesions can be done using various types of bioabsorbable implants, metallic screws, or osteochondral plugs. Metallic screw fixation shows high successful healing rates of 84% to 100%. The disadvantage of using metallic screws is that there is a need for a second procedure to remove the screws. Bioabsorbable implants do not require a second procedure for removal. They show successful healing rates of around 90%. These implants however show higher rates of complications. Osteochondral autograft or allograft plugs can also be used. The clinical outcomes are “good to excellent” in 72% of patients receiving allograft plugs. The overall aim of surgery is to promote cartilage reformation and/or repair of the articular surface to prevent early-onset osteoarthritis (8).

Differential Diagnosis

Meniscus injury

Osteoarthritis

Prognosis

Stable osteochondral lesions have a better outcome as compared to unstable lesions. Spontaneous healing typically occurs when stable lesions are treated with conservative treatment alone. There is no single uniform grading scale for lesions treated surgically. Unstable lesions and those that fail conservative management undergo surgical treatment which has a success rate of 30% to 100% depending on the technique utilized (8). However, a large majority of patients treated surgically will still develop early-onset osteoarthritis. Patients presenting during adolescence tend to have a better outcome than adult patients.

Complications

Chronic pain

Arthritis

Nonunion

Conclusion

The diagnosis and management of osteochondritis dissecans is carried out by an interprofessional team that consists of a radiologist, orthopaedic surgeon, physical therapist, and primary caregiver. The treatment is dictated by the patient’s age, time of presentation, the severity of symptoms, and stability of the lesion. There are several systems that have been developed to classify the lesions. The important feature is the degree of overlying cartilage involvement and mobility of the lesion. In stable lesions, conservative management is preferred with immobilization and protected weight-bearing for a length of time, that depends on which joint is involved. When conservative treatment fails the patient can be treated with drilling techniques (retroarticular or transarticular drilling). These procedures have shown healing rates and symptom improvement ranging from 92% to 100%. Transarticular drilling has slightly higher success rates. When lesions are unstable or displaced, surgical intervention is necessary. The outcomes of stable lesions are better than unstable lesions (9,10). 

References

1. Kessler JI, Jacobs JC, Cannamela PC, Shea KG, Weiss JM. Childhood Obesity is Associated With Osteochondritis Dissecans of the Knee, Ankle, and Elbow in Children and Adolescents. J Pediatr Orthop. 2018 May/Jun;38(5):e296-e299.

2. Edmonds EW, Polousky J. A review of knowledge in osteochondritis dissecans: 123 years of minimal evolution from König to the ROCK study group. Clin Orthop Relat Res. 2013 Apr;471(4):1118-26. 

3. Zanon G, DI Vico G, Marullo M. Osteochondritis dissecans of the talus. Joints. 2014 Jul-Sep;2(3):115-23.

4. Andriolo L, Candrian C, Papio T, Cavicchioli A, Perdisa F, Filardo G. Osteochondritis Dissecans of the Knee - Conservative Treatment Strategies: A Systematic Review. Cartilage. 2019 Jul;10(3):267-277. 

5. Michael JW, Wurth A, Eysel P, König DP. Long-term results after operative treatment of osteochondritis dissecans of the knee joint-30 year results. Int Orthop. 2008 Apr;32(2):217-21. 

6. Kubota M, Ishijima M, Ikeda H, Takazawa Y, Saita Y, Kaneko H, Kurosawa H, Kaneko K. Mid and long term outcomes after fixation of osteochondritis dissecans. J Orthop. 2018 Jun;15(2):536-539.

7. Zbojniewicz AM, Laor T. Imaging of osteochondritis dissecans. Clin Sports Med. 2014 Apr;33(2):221-50.

8. Bauer KL, Polousky JD. Management of Osteochondritis Dissecans Lesions of the Knee, Elbow and Ankle. Clin Sports Med. 2017 Jul;36(3):469-487.

9. Cheng C, Milewski MD, Nepple JJ, Reuman HS, Nissen CW. Predictive Role of Symptom Duration Before the Initial Clinical Presentation of Adolescents With Capitellar Osteochondritis Dissecans on Preoperative and Postoperative Measures: A Systematic Review. Orthop J Sports Med. 2019 Feb;7(2):2325967118825059. 

10. Yamagami N, Yamamoto S, Aoki A, Ito S, Uchio Y. Outcomes of surgical treatment for osteochondritis dissecans of the elbow: evaluation by lesion location. J Shoulder Elbow Surg. 2018 Dec;27(12):2262-2270.