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Lumbar Spine Stress Fractures — Spondylolysis
The Bone Stress Injury of Pars Interarticularis & Spondylolisthesis in Tennis & Cricket
Spondylo from spóndylos(Greek): Vertebrae
Lysis(Latin) from lusis(Greek): Loosening
Summary
- Spondylolysis involves a lesion at the Pars Interarticularis, a small bony bridge in the lumbar vertebrae. It can develop into a fracture and cause a vertebral slippage (‘Spondylolisthesis’).
- Spondylolysis mainly occurs in very active athletes, especially in adolescence when the athlete is immature skeletally.
- You can develop spondylolysis without pain.
- Sports involving repetitive lumbar hyperextension/hyperflexion (eg: gymnastics) or combined lumbar extension/rotation/side-flexion are most at risk (eg: tennis serve, cricket fast bowler etc.).
- Different cricket bowling actions and the tennis serve actions load the lumbar spine differently.
- Subjective history is key to diagnosis, objective clinical tests are not specific enough to rule in diagnoses however it will provide some ideas of deficits in strength, mobility, flexibility and stability that you can focus on during treatment.
- Diagnostic imaging (Xrays, PBS/SPECT imaging, CT Scans and/or MRIs) is required to rule out sinister pathology and to rule in a stress fracture, it aids prognosis (how long to rest the athlete for) but radiation exposure from different imaging types has to be managed/limited as much as possible.
- An active Spondylolysis will resolve with rest, anywhere from 2 weeks for stress reactions to 6 months for stress fractures,
- Load management is crucial in preventing stress fractures and overuse injuries.
- Whilst the athlete is resting (relative rest) there are many things that can be addressed such as technique education, strength and conditioning/cardiovascular fitness etc.
Overview
A Lumbar Spondylolysis is a defect of the Pars Interarticularis (Pars) (Niggemann et al., 2012). The Pars is a bony bridge in the spinal vertebrae and is the second most common site of overload injuries in tennis (shoulder is overuse enemy #1) (Alyas, Turner, & Connell, 2007). Pars injuries occur in up to 47% of adolescent athletes with low back pain (LBP) (Hollenberg, Beattie, Meyers, Weinberg, & Adams, 2002). Lumbar stress injuries have the highest prevalence in cricket fast bowlers and result in more games missed than any injury in cricket (J. W. Orchard, James, & Portus, 2006).
“If an active adolescent athlete develops backpain and stops their sport due to focal back pain, a spondylolysis should be considered until proven otherwise.”
(Herring, 2017) https://soundcloud.com/bmjpodcasts/low-back-pain-in-adolescents-professor-stanley-herring-talks-spondylolysis
A symptomatic spondylolysis is a significant injury due to the time away from sport required for it to resolve, which could be anywhere from 5–12 months (Debnath et al., 2007; Iwamoto, Takeda, & Wakano, 2004), however LBP is most often self-limiting and is easily managed conservatively (Trainor & Trainor, 2004).
An injury to the ‘Pars’ occurs on a stress fracture continuum over time, commencing with a stress reaction (early spondylolysis), stress fracture (late spondylolysis), fracture and slippage (spondylolisthesis) and finally spondyloptosis. This occurs when there is insufficient rest and bony remodelling following repetitive overload and bony breakdown (Boden, Osbahr, & Jimenez, 2001; Niggemann et al., 2012). Structural changes to the Pars, evident on diagnostic imaging, can often be asymptomatic but with repetitive loading and a high training load has potential to become symptomatic and metabolically active (Debnath et al., 2007).
Repetitive ballistic trunk movements in tennis and other sports with repetitive trunk rotation (eg: cricket bowlers) have been linked with a high frequency of pars stress reactions (D Foster, John, Elliott, Ackland, & Fitch, 1989). Pars defects are also common in any sport requiring hyperflexion and/or hyperextension of the low back including gymnastics, figure skating, diving and soccer (Kraft, 2002; Sassmannshausen & Smith, 2002).
A ‘Pars Stressy’ is a ‘low-risk’ stress fracture, with early detection, rest, and conservative treatment it is likely to completely heal (Boden et al., 2001; Iwamoto et al., 2004; Morita, Ikata, Katoh, & Miyake, 1995). However, it is often difficult to rest in sports with congested competitive calendars such as Cricket where a summer season now includes one-day matches, test matches and T20 matches, possibly related to the recent increase in injury rates to fast bowlers(J. Orchard, James, Kountouris, & Portus, 2010). Tennis in particular has one of the most congested calendars of any spot with very little ‘off-season/recovery’. The below graph demonstrates the length of the season/off-season between the EPL (football), NBA (basketball), NFL (American football/grid iron) and the ATP (tennis).
Functional Anatomy — What & Where it the Pars Interarticularis
All engineers who love Star Trek know where the structural vulnerabilities of the Starship Enterprise lie ….in the small links of the starship structure between big parts of the starship… duh!
It’s similar in the spinal segments, a big vertebral body at the front and a big spinous process at the back with a tiny pedicle bony bridge to the superior articular facets and a tiny pars bony bridge to the inferior articular facets and the spinous process. Add to this compression onto the pars of the bony inferior articulating process of the segment above when in extension and the structures gets challenged.
Spondylolysis Pathophysiology
What causes the pain? It is unknown whether the increasing separation of the Pars defect causes symptoms or if it is the torsional load on the intervertebral discs as a result of the separation (Debnath et al., 2007). Interestingly, in fast bowlers, pain may be more prevalent during the stress reaction stage of the injury but once the injury has progressed passed spondylolysis, pain may settle (Johnson, Ferreira, & Hush, 2012).
“Just because you see a pars defect, doesn’t mean it is the source of pain. This is an unusual fracture. What other fracture can occur without symptoms? Can be present by the age of 6 and has a hereditary predisposition?”(Herring, 2017) https://soundcloud.com/bmjpodcasts/low-back-pain-in-adolescents-professor-stanley-herring-talks-spondylolysis
Stress Fractures
Stress fractures are a non-traumatic injury, they occur from repeated exposures to loads below the ‘fracture threshold’ (Ohta-Fukushima, 2002). When the bony load exceeds the bony capacity there is an imbalance between bone resorption (by ‘osteoclasts’) and bone formation (by ‘osteoblasts’). Fitness plays a role in its development, there is general consensus that once surrounding muscles become fatigued there is increase load transmitted into the bone, this occurs as the shock-absorbing effect of bones is lessened leading to microdamage accumulation (Boden et al., 2001; Pepper, Akuthota, & McCarty, 2006).
Bone modelling during adolescence is vitally important for bony health/bone mineral density for later in life. More than 50% of adult bone calcium is acquired during adolescence (Loud, Gordon, Micheli, & Field, 2005).The “Bone & Tendon Bank” takes deposits and withdraws during adolescence but, post-puberty, only withdrawals. Females in particular are at greater risk of early development of Osteoporosis/Osteopaenaia if they don’t have an active childhood.
Non-mechanical factors increasing the risk of stress fractures include nutritional deficiencies, oral contraceptive use, hormonal imbalances, collagen abnormalities and metabolic bone disorders. Female athletes (especially female gymnasts, distance runners and figure skaters) are also at risk of the ‘female athlete triad’, particularly those with low body fat percentage, the triad includes an eating disorder, amenorrhea and osteoporosis (Loud et al., 2005). Additional risk factors include smoking, white race, and a family history of osteoporosis. Absent or less frequent menstural periods reduce oestrogen production, decreasing bone mineral density, increasing the risk of stress fractures (Boden et al., 2001). Males aren’t off the hook however, decreased testosterone levels following vigourous training can increase osteoclast production and bone resorption.
Boden et al. (2001) have classified stress fractures into low-risk and high-risk categories based on prognosis.
As stress fractures result from repetitive stress loading, training volume is a key component in the development of stress fractures, therefore load monitoring is critical. In the general population, there is an increased risk of stress fractures with > 16hrs/week of moderate or vigour activity (Loud et al., 2005).
The concept of a ‘weak 3rd week’ is known around sports medicine circles and involves the period after a spike in external load (eg: rapid increase in tennis serves/week or cricket overs bowled/week) where new repair tissue is laid down and the tissue is too immature 3–4 weeks after this spike to deal with further load (Johnson et al., 2012).
Orchard (2009) proposes that during an overload, immature tissue is damaged, mature tissue continues to function for short time but once the natural tissue turnover results in breakdown of the mature tissue, the previously damaged immature tissue is not able to replace it (J. W. Orchard, James, Portus, Kountouris, & Dennis, 2009).
Stress Injuries to the Pars
Cadaveric studies found that full flexion and extension movement bend the inferior articular process enough to cause a fatigue fracture of the pars Interarticularis (Green, Allvey, & Adams, 1994).
The pars is the weak link in the vertebrae due to its small size. Pars fractures occur most frequently (70%+) at L5, likely due to the amount of flexibility required at the lumbosacral junction and the quick changes of direction that can occur between the spine and the pelvis. Due to the relatively elastic nature of the intervertebral disc in adolescence, the shearing forces instead loads the bony structures in the lumbar spine. These bony structures (pars interarticularis, transverse process, neural arch) are underdeveloped at this time and this increases the increases the risk of bony failure (D Foster et al., 1989).
It is generally agreed that the pars is vulnerable to damage from repetitive lumbar side flexion, rotation and hyperextension (eg: tennis serve, tennis open stance ground stroke and cricket fast bowling action).
Once a fracture has developed at the Pars, the vertebra may translate anteriorly (slip forwards) over the vertebrae beneath it, become an spondylolisthesis.
Thre are 6 types of spondylolisthesis, first described by Wiltse in 1976 (Wiltse, Newman, & Macnab, 1976):
1. Degenerative — natural ageing misalignment of vertebrae
2. Isthimic — Pars fracture causing vertebra anterior translation — most common in athletes
3. Congenital — birth defect at L5-S1, ‘dysplastic spondylolisthesis)
4. Traumatic — Pars fracture or neural arch fracture from sudden impact/injury
5. Pathologic — bony disease, such as Paget’s disease, leading to vertebral instability
6. Iatrogenic — slippage due to surgical removal of large portions of the spine
A common Spondylolisthesis grading system is also used in orthopaedics and was first proposed by Meyerding in 1932 (Meyerding, 1932), it measures the severity of vertebral slippage:
Grade 1- 1–25%
Grade 2 - 26–50%
Grade 3 - 51–75%
Grade 4 - 76–100%
Grade 5 ‘Spondyloptosis’, L5 completely slipped over S1
A non-bony union of a pars defect doesn’t always lead to instability, fibrous healing can occur and have good long-term outcomes (Iwamoto et al., 2004).
A controversial idea from Millson et al. (2004) suggests that pars stress fractures are possible an advantageous physiological adaptation to fast bowling and reduce mechanical pressure on the vertebra and avoid pain (Millson, Gray, Stretch, & Lambert, 2004). This follows a similar ‘pathoanatomical-advantage theory’ to that of asymptomatic SLAP lesions in the shoulders of baseball pitchers helping to increase shoulder mobility.
Incidence of Pars injuries
General population studies found males to have twice as many lumbar stress injuries than females (Beutler et al., 2003).
Spondylolysis is most common in children 5–10yo or in athletic adolescence (Wiltse, Widell Jr, & Jackson, 1975), however only occurs in 5% of the general population and is mostly asymptomatic.
Incidence — Cricket
Cricket fast bowlers can be required to bowl up to 50 overs (50x6balls) or more during a 4–5 day test match, several prominent Australian pace/fast bowlers have fallen victim to pars injuries on numerous occasions recently…. no doubt contributing to the nations drop in test rankings (…a good excuse if we Aussies needed one).
Low back injuries account for 37–55% of injuries in junior cricket fast bowlers (Davies, Du Randt, Venter, & Stretch, 2008). In 36 asymptomatic professional adult fast bowlers (mean age 26), 81% had pars abnormalities (CA Ranson, Kerslake, Burnett, Batt, & Abdi, 2005). Another study found 33% of junior fast bowlers had at least one pars abnormality, mostly at the L5 level and on the non-dominant arm side (Crewe, Elliott, Couanis, Campbell, & Alderson, 2012)
Incidence — Tennis
Prevalence of trunk injuries in tennis have been reported at 3–21% (Abrams, Renstrom, & Safran, 2012). Younger players seem more likely to get a back injury, 6 years of injury surveillance at the USTA Boys National Championship found the back as the most common anatomical site of pain (3.4%) (Hutchinson, Laprade, Burnett, Moss, & Terpstra, 1995). An 1980s study found 38% of 148 professional tennis players withdrew from a tournament due to low back pain (Marks, Haas, & Wiesel, 1988).
In a review of 320 non-tennis athletes, stress fractures had an incidence of less than 1% and most commonly occur in the tibia (49.1%), tarsals (25.3%) and metatarsals (8.8%) (Boden et al., 2001). Whereas, in 139 elite tennis level players, stress fractures had a total incidence of 13%, 16% of these are Lumbar Spine Pars Interarticularis stress fractures, followed by the tarsal navicular (27%), metatarsals (16%) and the tibia (11%) (Maquirriain & Ghisi, 2006).
If you compare the total incidence of stress fractures from multiple sports from a 1996 study by Brukner et. Al., two things stick out (see below pic). Firstly, as aforementioned, incidence of stress fractures in tennis is far greater than that of other sports (13% vs 1%). Secondly, Pars stress fractures occur much more often in Tennis than in other sports (16% vs 3%), Dancers come close (9%) (Brukner, Bradshaw, Khan, White, & Crossley, 1996).
Tennis Australia data from 2013 found a 17% incidence of LBP in 12–18 year old male players, resulting in an average of 34 days of missed training which represented half of all days lost due to injury (Campbell, Straker, O’Sullivan, Elliott, & Reid, 2013). Pars injuries occur more often in elite tennis players under 18 years old (Maquirriain & Ghisi, 2006). Studies on asymptomatic tennis players have found a Spondylolysis incidence of 28.3% (Alyas et al., 2007) and 30% (Rajeswaran, Turner, Gissane, & Healy, 2014). The below table compares MR findings on asymptomatic Tennis vs Cricket players from the above studies.
Why talk about players who don’t have pain but have pars defects on MRI? We’ll discuss this further in the ‘diagnostic imaging’ section below but it relates to the lack of specificity of MR images to find ‘metabolically active’ lesions compared to older/chronic lesions.
Unilateral Pars defects occur rarely compared to bilateral defects. A 1951 survey of 4,200 skeletons found a 1:6 ratio of unilateral to bilateral defects (Roche & Rowe, 1951). In a large study (n=134), bilateral Pars defects were noted in 78% of the patients compared with 22% unilateral defects (Fujii, Katoh, Sairyo, Ikata, & Yasui, 2004). A unliteral Pars defect has a higher healing potential than a bilateral Pars defect (Debnath et al., 2007; Iwamoto et al., 2004; Sys, Michielsen, Bracke, Martens, & Verstreken, 2001).
Incidence — Field Athletes and Gymnasts
Any other athletes who repetitive ‘bounce’ into and out of coupled lumbar spine extension and rotation/side flexion repetitively also have a high prevalence of Spondylolysis. One study found a very high prevalence in Athletic throwers (Discuss, Javelin, Hammer Throw, Shot-Put), 26.67% (compared to 8% in general population) with 66% of these being symptomatic (Soler & Calderón, 2000).
Sport Specific Pathobiomechanics — How it goes wrong
Tennis Serve
During the tennis serve, the lumbar spine experiences lateral flexion forces 8 times greater than those encountered during running (Campbell et al., 2013; Chow, Shim, & Lim, 2003).
Young/at-risk tennis players spend increased time training on court and the repetitive and intense training periods put them at increased risk of developing overuse injuries. The serve, in particular the kick serve or top spin serve, has been reported as a higher risk serve (Abrams et al., 2012). Introducing this serve into a ‘musculoskeletally immature’ player may increase the risk of developing lumbar spine stress injuries such as spondylolysis or spondylolisthesis (Alyas et al., 2007).
An interesting finding in the Tennis Australia study (Campbell et al., 2013) was that the flat serve had greater lumbar loading than the kick serve, which is the opposite to what is commonly suggested (Abrams et al., 2012). My thoughts would be that the flat serve has more ground reaction force and compression and it is this compression, moreso than the amount of coupled extension, rotation and lateral flexion, that contributes more to lumbar loading. The Campbell (2013) study does suggest that the ‘leg drive’ emphasis of the serve may be contributing to this. Further studies are needed if there are ways of serving without compromising racquet velocity.
A study of the tennis serve in Tennis Australia National Academy players found that painful players had less trunk rotation during the windup of the serve and more rotation in the opposite direction during the follow-through. Painful players also increased their lateral trunk flexion in the windup, around 50% moreso than the painfree players (Campbell et al., 2013). The coupled movement of lumbar extension, rotation and lateral flexion, combined with the ground reaction force from rear leg drive in the serve, puts up to 10x body weight through the lower trunk and this has been suggested as a potential mechanism for abdominal tissue strain and low back injuries in adolescent players.
Poor conditioning and fitness also has negative flow-on effects. Tournament Physiotherapists at Junior events will note the high incidence of abdominal strains (opposite to racquet hand) from repetitive trunk flexion and rotation, however the other muscles at risk of fatigue and injury are erector spinae and multifidus muscles due to repetitive trunk extension and rotation (Perkins & Davis, 2006). As previously noted, muscle fatigue increases load on nearby bones (Boden et al., 2001; Pepper et al., 2006). The normal trunk extensor to flexor strength ratio has been reported as 1.3:1, and this has been found to be reduced in athletes with LBP (DN Foster & Fulton, 1991).
A recent increase in the open-stance forehand (trunk facing the net) has increased the incidence of spondylolysis in the lower back and hip injuries (due to the sudden anterversion and lumbar hyperextension during the stroke) (Ruiz-Cotorro, Balius-Matas, Estruch-Massana, & Angulo, 2006). Due to the extra rotation required from the lumbar spine in open stance groundstrokes, unilateral injuries would be more common as these occur more with repetitive rotation rather than repetitive extension (Alyas et al., 2007).
No association has been found between age, sex and skill level on injury rate in tennis players whereas volume of play (load) clearly contributes with both tennis (Abrams et al., 2012) and cricket bowlers (J. Orchard, James, Kountouris, & Portus, 2010).
Cricket
Fast bowlers have a high prevalence of bony vertebral stress lesions (67%) (Johnson et al., 2012) compared with the general population (6%) (Beutler et al., 2003). Some studies have found unilateral spondylolysis more likely on the contralateral side to the bowling arm lumbar side flexion away from the bowling arm (Debnath et al., 2007; Johnson et al., 2012), but there have been numerous other studies reporting equal rates of bilateral and unilateral injuries (Johnson et al., 2012). Lumbar side flexion and rotation during bowling loads the pars interarticularis and is also is a mechanism for disc herniations (d’Hemecourt, Gerbino, & Micheli, 2000) especially when considering the 6x body weight ground reaction force during the delivery (Portus, Mason, Elliott, Pfitzner, & Done, 2004).
A 2008 study examined the history of LBP in elite Australian female fast bowlers, the differences in lumbar spine and hip range of motion (ROM) in those with and without LBP and differences between male and female lumbar spine and hip ROM (Stuelcken, Ginn, & Sinclair, 2008). The authors found that 54% of their female fast bowlers had a LBP history, however it is difficult to know whether that was under-reported. They suggest their sample was a ‘survivor population’, as those female players with bad enough back pain may have switched to spin bowling or focused on becoming a batting specialist instead.
Female fast bowlers with LBP had less lumbar lateral flexion ROM on the bowling arm side, compared with those without LBP. Female bowlers had greater hip extension ROM than male bowlers, which may be beneficial in reducing repetitive lumbar hyperextension and also add to ball speed (Stuelcken et al., 2008).
Cricket — Bowling Action
Foster et al. (1989) suggested several intrinsic factors which can increase the risk of back pain in bowlers including flat feet, a reliance on upper body strength for ball velocity, excessive trunk rotation between back foot impact (BFI) and front foot impact (FFI) and a higher release position at FFI from end of range hip/knee extension. They also reported the link between increased external load (nr of overs) and back injuries.
Different bowling actions have different risks for developing a pars injury (Johnson et al., 2012). One study found 89% of bowlers with a lumbar spine stress injury had a mixed action (Portus et al., 2004), due to excess trunk rotation relative to the hips and a large contralateral lumbar side-flexion motion coupled with large ground reaction forces at BFI. Other research suggests that excessive contralateral flexion and ipsilateral rotation of the lumbar spine from FFI to ball release is more likely to cause a contralateral stress fracture to the rars rather than the trunk rotation between BFI and FFI (Glazier, 2010; C. A. Ranson, Burnett, King, Patel, & O’Sullivan, 2008).
The side-on action is the textbook/traditional action and it may be that front-on bowlers have been encouraged to develop a side-on action which has resulted in the hybrid mixed action over time (Johnson et al., 2012). A great post by a sports and exercise specialist on back pain in cricket compiling several studies on bowling actions found: 65% of bowlers use a mixed action, 25% front-on/semi-open action and 10% a side on action.
Below is a summary of the bowling actions but the key message is: ball speed is the same across all the actions so coaches should screen their players and try to make changes early in the development of their fast bowlers.
Perhaps the most dangerous bowling action of all was only seen once in history and it proved disastrous for not only cricket but Australia as a whole:
Cricket — QL Asymmetry
Another area of study in cricket bowlers has been focused on lumbar spine muscle morphology, particularly asymmetry of quadratus lumborum (QL).
Here is a quick summary of this research in chronological order:
· Big Asymmetry is a Big Problem — An increased QL size on the dominant side increases risk of developing a pars injury (C. Engstrom, Walker, Kippers, & Buckley, 2000; C. M. Engstrom, Walker, Kippers, & Mehnert, 2007).
· The Bigger The Asymmetry the Bigger The Problem — Bowlers with a QL asymmetry >25% have a 58% probability of developing a pars injury (Craig Ranson, Burnett, O’sullivan, Batt, & Kerslake, 2008), compared with 4% for those who had an asymmetry of 5% or less.
· Oh Wait! It’s protective! — Asymmetrical QL hypertrophy is a protective trunk stabilising mechanism to help control the large lumbar side-flexion moment during bowling between FFI and the follow-through (C. Ranson et al., 2008).
· Ummm.. There’s asymmetry all over the place! — 55% of junior male fast bowlers have >10% QL asymmetry, but on both sides of the trunk relative to the bowling arm (Kountouris, Portus, & Cook, 2012b).
· Sorry….Asymmetry is No Problem — There is no link between QL asymmetry and lumbar spine bone stress injuries (Kountouris, Portus, & Cook, 2012a).
· The Bigger the Asymmetry the Lesser The Problem — Bowlers without pain have a larger asymmetry than those who develop an injury (Kountouris, Portus, & Cook, 2013).
Cricket — External Load
Many early studies found an increased risk of injury with high bowling workloads (Bell, 1992; Dennis, Finch, & Farhart, 2005), for example bowlers who have less than 3.5 rest days on average between matches had a 3.1x increased risk of injury when compared with those had more than 3.5 rest days (Dennis et al., 2005). Injury risk from a workload of 51–99 overs has been shown to be no different to a workload of 50 overs or less over a short period (17days) (J. W. Orchard et al., 2015b). However, workloads of more than 100 overs in that short period did increase absolute injury risk, although it is uncommon.
Instead it is a spike in bowling workload over a short time that has an increased likelihood of injury, particularly 3–4 weeks later, a flashback to the previously mentioned ‘weak 3rd week’ (J. W. Orchard et al., 2015a, 2015b; J. W. Orchard et al., 2009). When fast bowlers exceed 50 overs in 5 days, they have a 50% increased injury risk (14% likelihood in the next month, compared to 9%). Furthermore, bowling substitutes are not permitted in cricket (fielding subs are ok), therefore once a team loses a bowler during a match, the other bowlers workloads spike (J. W. Orchard et al., 2015a).
Risk of injury was more likely in the period of 21–28 days following a big spike in bowling load in a study of Australia pace bowlers between 1998–2008 (J. W. Orchard et al., 2009). Over the summer, the highest injury incidence top bowlers was around January once the one day internationals (ODIs) commenced, however given that the test series is at its peak 3–4 weeks before the ODIs start and bowlers are capped to 10 overs during the ODIs, this increased injury incidence could be explained by the high loads during the test series (J. W. Orchard et al., 2009).
“It’s not the destination, it’s the ‘road to load’ that matters’ (Pluim & Drew, 2016) — a great title for paper on tennis injury prevention 2016, however it appears it rings true for cricketers too. For bone stress injuries, a career match workload of > 1200 overs is protective. Young players should therefore be working to gradually increase their bowling load to condition their bones to withstand the high workloads of a professional bowler (J. W. Orchard et al., 2015a). This can only be achieved through careful load management.
Cricket — Musculoskeletal characteristics
Flat feet, tight hamstrings, excessive lordotic posture and poor lumbar flexibility have all been suggested to play a role in the development of a lumbar spine stress injury (D Foster et al., 1989; Johnson et al., 2012).
Fatigue during matches has also been shown to increase the risk of sustaining a lumbar spine stress injury. For example, during an 8-over spell, a fast bowler will gradually fatigue and increase the shoulder counter-rotation which increases the load through the pars (Portus et al., 2004).
Poor conditioning and early fatigue during matches is more common in adolescent fast bowlers and increases shoulder-hip counter-rotation increasing pars injury risk (C. A. Ranson et al., 2008.
Subjective — What they say
The player will report a focal LBP with their activity that is less with rest. Eventually the pain sticks around following exercise (Boden et al., 2001). The player may report that they were able to push through the pain for a while (weeks) but then it suddenly became too painful to go on.There may be a referral of pain into the ipsilateral buttock.
A patient with a rare high-degree slip may report neurological symptoms, in these patients it’s most commonly a L5 radiculopathy from a L5 on S1 slip (Boden et al., 2001) .
The tennis coach may report that the player has less trunk rotation during wind up in the serve and doublehand backhand and perhaps more lumbar rotation in the opposite direction during the follow through (Campbell et al., 2013).
The cricket bowler may report a decrease in pain-free max ball speed, the speed at which they can bowl pain-free. The tennis player similarly will report a decrease in pain-free max serve speed.
Objective — What you see
“This is a radiological diagnosis.”
(Herring, 2017) https://soundcloud.com/bmjpodcasts/low-back-pain-in-adolescents-professor-stanley-herring-talks-spondylolysis
There may be localised pain on palpation (Boden et al., 2001) however this can also been found in asymptomatic players (Crewe et al., 2012). In patients with metabolically active spondylolysis there may be paraspinal and hamstring hypertonicity of muscle spasm (Garry & McShane, 1998), however again this may also be found in asymptomatic players. You shouldn’t find any dural tension(Herring, 2017).
There is a general lack of evidence for specific lumbar spine ‘special tests’ in detecting lumbar spine pathology (Dreyfuss, Michaelsen, Pauza, McLarty, & Bogduk, 1996; Maigne, Aivaliklis, & Pfefer, 1996). A ‘one-leg lumbar hyperextension test’ has been described (Jackson, Wiltse, Dingeman, & Hayes, 1981), the patient stands on their ipsilateral leg and leans back (hyperextends lumbar spine), however this has since been found to not be useful in detecting active spondylolysis (Masci et al., 2006).
However, objective testing will give you the opportunity to screen the athlete for any kinetic chain deficits in strength, mobility, stability and flexibility and provide an idea of what to address during treatment
Diagnostic Imaging — What machines see
An explanation of four complementary imaging tests is provided by Ruiz-Cotorro (2006):
Diagnostic Imaging — Xray — The Classic “Scotty Dog Collar”
The classic sign of a pars defect on XR imaging is from the oblique lumbosacral view and is called a ‘Scotty Dog Collar’ due to the resemblance of the structure to a Scottish Terrier. However XR imaging may not reveal any findings for months until the latter stages of an acute Spondylolysis when a fracture line may be evident (Niggemann et al., 2012).
Furthermore, the oblique view may be an unnecessary view as it adds another exposure to radiation and may not always show a stress fracture. A standing AP and lateral view is enough as you’re only looking for a spondylolisthesis and ruling out other sinister pathology (Herring, 2017) .
The below picture covers the ‘Scotty Dog Collar’ sign:
Diagnostic Imaging — Bone Scans (PBS/SPECT)
Bone scans (PBS/SPECT) are highly sensitive for detecting bony stress injuries. However, bone scans lack specificity, uptake of the radioactive material may cause intense signals by osteomas, osteomyelitis and other orthopaedic conditions in the area. Additionally, many asymptomatic players may have an increased signal in the Pars area (Ruiz-Cotorro et al., 2006).
Diagnostic Imaging — CT Scans
CT Scans have good detection and localisation of small stress fractures in the spine and pelvis. A fine slice CT scan will be used targeting the area of ‘high metabolic activity’ found on a PBS/SPECT image.
Diagnostic Imaging — MR Imaging
MRIs have a higher specificity than CT scans for isolating bony injury from soft-tissue injuries and is used to help grade time to recovery for most other stress fractures (Boden et al., 2001; Crewe et al., 2012).
For pars fractures, a MR imaging grading system was proposed by Hollenburg (2002)
Using MR imaging to predict injury
Acute bony stress on MR imaging in asymptomatic elite fast bowlers were likely to be symptomatic within 4 weeks if they weren’t rested and at risk of future stress fracture development (CA Ranson, Burnett, & Kerslake, 2010). An incidental finding in Kountouris’ 2013 paper on QL asymmetry was that bowlers who had bone oedema on preseason MR imaging ended up with symptomatic lumbar bone stress injuries, however admits that further research is required to back that up (Kountouris et al., 2013).
Diagnostic Imaging — So what imaging will we order for who?
As aforementioned, MRI can pick up many asymptomatic spondylolysis lesions and may result in false positives. Radiological Imaging and Nuclear Imaging involves a risk of radiation exposure, especially to children/adolescence and reproductive organs (for low back imaging).
In elite sport, if an athlete needs an exact diagnosis and prognosis you may need to do a full imaging workup:
- Rule out and/or measure the rate of a Spondylolisthesis. Rule out other sinister pathology (bony tumours, other fractures etc.). (XR Imaging)
- Rule in a metabolically active Spondylolysis (as opposed to a chronic and asymptomatic spondyloysis). (PBS & SPECT)
- (If needed) Grade a metabolically active stress fracture (based on size/location of fracture) in order to get a prognosis. (CT Scan)
However, if the athlete/coach/parents are happy to adhere to general advice (relative rest for 2–3 weeks to see if things will settle down, followed by gradual return to playu) then it may not be necessary to expose the athlete the above.
A gold standard for grading an active spondylolysis is suggested by Masci et al. (2006) and has been advocated recently by Dr Stanley Herring (2017)
- Standing AP and Lateral Xray to rule out sinister pathology and to look for a spondylolisthesis.
- If no evidence of a stress fracture and there is no need to get an exact return to play forecast, then there is no need to further expose an adolescent to further radiation.
However, if a prognosis is required for an elite athlete or if suspecting a strss fracture:
- PBS with SPECT — allows you to determine whether a fracture is metabolically active.
- If PBS is positive, reverse-gantry CT Scan will give a more accurate picture of the fracture.
Although MRI is tempting due to non-radiation and it shows other patholgoies well, it does not show stress reactions and single cortext fractures well, and they’re the ones we want to know about as we need to more aggressive in resting the athlete.
If you suspect your player has a stress fracture, get your Sports Physician on board for imaging and a medical evaluation to rule out other risk factors contributing to poor bone density (espec with female athletes).
Differential Diagnosis
Before proceeding with a diagnosis of a spondylolysis/pars stress fracture, other diagnoses need to be ruled out such as: muscle strain, nerve injuries, neoplasms, atypical Scheuermanns (thoracolumbar region), other stress fractures (transverse process, vertebral end plate), disc herniation, primary inflammatory conditions and infections (Boden et al., 2001; Trainor & Trainor, 2004). Conditions from the hip, pelvis and viscera should also be ruled out, renal issues, bowel pathology and reproductive organ disease also mimic LBP (Trainor & Trainor, 2004).
There should be no concurrent fever, unexplained weight loss or unremitting night pain indicating sinister pathology.
Treatment — What to do about it
The best treatment is prevention. Load monitoring will assist in reducing the risk of a player developing a stress reaction. Tennis players and cricket bowlers should be encouraged to report LBP when it occurs so it can be monitored by their sports medicine team.
Training programs for high-risk sports should consider biological age of their players as well as physical and psychological maturity, and adjust training intensity, duration, frequency and recovery to avoid overuse injuries (Maffulli, Longo, Spiezia, & Denaro, 2010). Simple external load monitoring such as counting number of baseball pitches, number of tennis serves or number of cricket overs/week can help monitor for spikes, and then act on these spikes accordingly (eg: rest the player 3–4 weeks after a spike).
Training loads and specific external loads (bowling, serving etc.) during rapid growth rate should also be monitored closely as there may be an increased risk of musculoskeletal injury (Maffulli et al., 2010).
Cricket bowling coaches should note that ball speeds are similar across all bowling actions, therefore they should target bowlers who are at increased risk of injury due to using a mixed action and help them develop another action.
Coaches of adolescent fast bowlers who are tracking towards professional/elite level should gradually increase their bowling load. As previously mentioned, a career match workload of > 1200 overs is protective of bone stress injuries (J. W. Orchard et al., 2015a).
A prevention screening strategy has been suggested (Crewe et al., 2012):
- Regular physical exam with a subjective flagging LBP symptoms and provocative testing for Pars injury.
- MRI if positive Pars injury signs or symptoms present.
- If MR positive for bone marrow oedema, rest from the sport to prevent injury from getting worse.
The majority of low-risk stress fractures can be treated with rest followed by a gradual return to sports program, the Pars stress fracture has been classified as low-risk due to its ability to heal up with rest (Boden et al., 2001)..Even a pars defect with a non-bony union can create a pain-free fibrous union with conservative treatment (Iwamoto et al., 2004).
Bracing, with activity restriction, has been suggested to be an effective analgesic via ROM restriction (Iwamoto et al., 2004; Zurakowski, Kriemler, & Micheli, 2002). Ruiz-Cotorro et al. (2006) recommends using a brace when the spondylolysis is metabolically active to help reduce the pain sooner. Sys et al. (2001) used a Boston overlap brace (has a hinge allowing hip extension) with their competitive athletes with spondylolysis (Sys et al., 2001). However recovery is the same with or without bracing, and the braces have been shown to not reduce segmental motion (sometimes they increase it in fact). They can be prescribed as a behavioural modifier, if the athletes symptoms haven’t settled by 3 weeks and you really want to make sure they aren’t participating in aggravating activities (Herring, 2017).
It has been suggested that tight anterior hip capsule structures and/or iliopsoas muscles can cause anterior rotation of the pelvis, increasing lumbar lordosis and the development of low back pain in bowlers (MacKay & Keech, 1988; Trainor & Trainor, 2004). You can try some anterior hip capsule and/or iliopsoas tissue release techniques to assist with this.
An off-season back strength program emphasising maintenance of the extensor to flexor strength ratio (1.3:1) is also recommended (Trainor & Trainor, 2004) however I haven’t seen this pop again in the research from the past 10 or so year, so I’d probably just focus on general trunk and posterior chain (glutes, hams, calf) strength.
The Tennis Physio Treatment Ideas
- Relative rest (from the aggravating sport/action)
- Cross training, incl cardio targeting sport-specific work/rest ratios.
- General cardiovascular fitness
- Footwear changes, podiatry review if needed
- Sports Dietian review (if needed)
- Sports Physician medical review (if needed)
Address deficits in kinetic chain strength, stability, flexibility and stability:
- Trunk, Spinal, and lower limb mobility exercises or manual therapy (eg: ankle dorsiflexion, hip extension, thoracic rotation)
- Address flexibility deficits of soft tissues around the trunk and lower limbs
- Address ‘Triple Flexion’ strength deficits (lower limb)
- Address ‘Triple Extension’ strength deficits (lower limb)
- Address trunk and lower limb strength deficits
- Spinal manual therapy where required
Address environmental and sport-specific items such as:
- Equipment changes (eg: racquet changes — weight, balance, string tension, string type, string pattern, head size etc.)
- Technique checks by coach
- Court movement checks
- Video analysis of players technique from past footage.
- Once returning to sport, monitor external load including serve count (for shoulder, lumbar injuries) and training load (RPE x Mins) for all injuries
- In Tennis when shifting to a clay season from a hardcourt season, be aware of the sudden increase in lumbar loading from a higher bounce/higher topspin
Prognosis
The majority of players will become asymptomatic and develop no long term issues, however only 30–50% of stress fractures will demonstrate bony healing (Boden et al., 2001).
There are different ideas of prongosis in the literature depending on the sport.
In elite cricket, bowlers can take 6–12 months to return to play following symptomatic spondylolysis (Debnath et al., 2007).
In tennis players, Ruiz-Cotorro et al. (2006) reported return to play timelines of around 2 months for acute on chronic (flare-up) spondylolysis and 4 months for developing or active spondylolysis.
Authors generally recommend that athletes with acute spondylolysis return to sport in 5–7 months whereas those with acute-on-chronic spondylolysis could return in 2–5 months (Iwamoto et al., 2004; Standaert, 2002).
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