In this negligence action against the District of Columbia (“District”), appellant Gary Messina (“Messina”), father and next friend of minor Karyne Messina (“Karyne”), seeks reversal of the entry of judgment as a matter of law in favor of the District, contending that the testimony of his expert witness was sufficient to establish the requisite standard of care. Messina also cоntends that it was reversible error for Judge Burgess to deny his motion to amend the pre-trial order to permit the testimony of a new witness. 1
For the reasons set forth below, we hold that, because Messina failed to present expert testimony sufficient to establish the standard of care owed to Karyne by the District, he did not present a prima fаcie case of négligence; accordingly, we affirm the trial court’s grant of the District’s motion for judgment as a matter of-law.
I.
In September 1990, while in the fourth grade at the Lafayette Elementary School in the District, Karyne Messina broke her arm *537 when she fell to the ground while playing on a set of monkey bars at the school’s playground. The monkey bars used by the child were known as a horizontal ladder; that is, a ladder of evenly-spaced bars bolted parallel to the ground to four wood posts approximately eight feet high. Karyne was swinging from one bar to the next with her hands when one bar rotated in its sockets, causing her to lose her balance and fall to the ground. 2 Karyne struсk the ground, which she described as “hard packed mud, dirt” with some wood “chips” on it, with her left hand and arm, causing a fracture which required her arm to be kept in a cast for several months. According to her testimony, Karyne continues to experience pain in the arm when she plays sports and during changes in the weather.
On December 27, 1991, Messinа brought this claim against the District, maintaining that the District was negligent in failing to make the ground safe beneath the monkey bars where Karyne fell. In a jury trial beginning on January 4,1994, Messina presented Mr. Paul Hogan (“Hogan”), a playground designer and builder, as an expert on standards of care in the construction of playgrounds. Hogan testified that “within the public playground industry” there was a standard of care that required the District to have a certain quantity and quality of resilient cushioning material, such as mulch, wood chips, or chopped tires, on the ground under the monkey bars where Karyne fell. The witness testified that these standards had first been developed in 1933-34 in a publication by the American Recreation Association which advised the public of the need for playground safety. They were later developed into a handbook, which contained two articles written by Hogan, entitled Guidelines for Public Playground Safety, which was published by the Consumer Products Safety Commission (“CPSC”) in 1981 (“1981 Handbook”), and again in 1991, a year after Kar-yne was injured, when the guidelines were “fine tuned.” Hogan testified that the 1981 standards “had been accepted ... worldwide as the guidelines for proper playground safety development ... even though they weren’t mandated by law and they weren’t enacted by Congress.”
In particular, Hogan testified that, to avoid fracturing a human skull, cushioning material below the monkey bars should provide a surface impact resistance of no more than 200 G’s. 3 Hogan stated that the 200 G guideline was developed in tests done on the human skull because “that is the only uniform part of a human body,” and that based on these tests, the 1981 Handbook “recommends” a playground surface resistance of no more than 200 Gs. 4 Mr. Hogan further testified that, in his opinion in order to meet that standard, using wood chips or similar material as cushioning, it would be necessary to provide a layer approximately ten to twelve inches deep for playground equipment eight feet high like the equipment Karyne was using when she was injured.
At the close of Mr. Hogan’s testimony, the trial court granted the District’s motion for judgment as a matter of law, ruling that Hogan’s testimony failed to establish a standard of care which the District was required to follow. This appeal followed.
II.
“The plaintiff in a negligence action bears the burden of proof on three issues: the applicable standard of care, a deviation from that standard by the defendant, and a causal relationship between that deviation and the plaintiffs injury.”
Toy v. District of
*538
Columbia,
Through Mr. Hogan, Messina presented evidence that, as of the time of the accident, various authorities had recommended the 200 G cushioning guideline to prevent skull fractures as a desirable safety practice, but that the guideline had not been promulgated as a law or regulation. Hogan expressed his opinion that this guideline represented the worldwide standard for public playground safety. Hogan also testified that in order to meet that guideline, and for a fall of eight feet, ten to twelve inches of certain cushioning materials was necessary. The issue before us is whether Hogan’s opinion was legally sufficient to permit this claim of negligence to go to a jury. We hold, on the circumstances presented here, that it was not.
The essence of Hogan’s testimony was that the applicable standard of care is determined in a two-step process. First, the 200 G guideline determines the limit in order to avoid skull fractures. Second, to meet the 200 G guideline, Hogan opined thаt cushioning material must be provided to a specified depth depending upon the cushioning material and the height of the fall. Both steps must be satisfied in order to establish a standard of care.
With respect to the first step, Hogan testified that the 200 G guideline was promulgated in the 1981 Handbook. 5 The 1981 Handbook specified, however, that any guidelines contained therein were not to be considered as CPSC standards, and were not mandatory. The 1981 Handbook, moreover, did not specify the depth of cushioning materials, which varies with the height of the equipment and the type of cushioning, necessary to meet the 200 G guideline. Nor did the 1981 Handbook provide a comparable guideline to avoid a broken arm like the one sustained in this case. In short, the 1981 Handbook did nothing more than recommend a 200 G guideline for skull fractures. Hogan, however, testified that the 200 G guideline, in his opinion, was a national standard for playground safety, and we will assume, without deciding, that it was sufficiently established as a national standard in this case. We now turn to thе second step'of the process.
Hogan testified that, through a series of tests he conducted some years after the 1981 Handbook was published, he determined that ten to twelve inches of mulch or similar material would meet the 200 G guideline for a fall of eight feet. A chart reflecting the results of his research was prepared by him and admitted into evidence. 6 Hogan also testified that the chart had been published many times, but he did not say when the *539 tests were performed or when or where the chart had been published. Hogan acknowledged that the results of his research have not been accepted by any government agency. 7
We conclude that Hogan’s testimоny, with respect to the depth of cushioning material, even when viewed in the light most favorable to Messina,
see Toy,
The only possible basis given by Hogan for his opinion that ten to twelve inches of mulch provides a national standard of care is his testimony that manufacturers of playground equipment, in their catalogues, recommend cushioning material of specific depths. That testimony, however, was objected to by the District on the grounds that Hogan did not specify which manufacturers provided the information or whether the information was being provided to customers by manufacturers before the injury occurred. 8 Although counsel for Messina agreed to elicit clarification on those points, he never did so. Thereforе, the record is silent whether, at the time of the injury, warnings concerning the depth of cushioning were being provided by manufacturers of the playground equipment.
Hogan’s testimony is not unlike the expert’s testimony in
Toy, supra,
Messina relies on
District of Columbia v. Peters, supra,
In sum, we hold that Hogan's testimony failed to establish the standard of care against which an impartial trier of fact could reasonably assess the District’s actions in this case. “Without sufficient proof of the standard of care,” the trial judge did not err in not sending the case to the jury.
See Carmichael,
Affirmed.
Notes
. Messina sought to introduce the testimony of Dale Miller, the president of the company that manufactured the playground equipment involved in this case. It is unclear exactly what
the
content of Miller’s testimony would have been, but it appears from the record that Messina was aware of the witness' identity long before discovery hаd closed. For that reason, we perceive no abuse of discretion on the part of the motions judge in denying the motion to amend.
See Daniels v. Beeks,
. Messina does not contend that the rotation of the bar, or the fall itself, were the result of negligence by the District.
. A "G” is "a unit of force equal to the gravity exerted on a body at rest.” Webster’s II, New Riverside University Dictionary. According to Hogan, a "G is the weight of your body."
. Hogan testified that the tests developing the 200 G guideline "evolved from the safety belt testing conducted by General Motors ... in the late '50s and early '60s, where they had these dummies in cars and they were strаpped in and they would smash a car through a concrete wall and the dummies would go forward and hit the dashboard or hit the glass and they had instrumentation in those dummies that indicated that an impact of more than 200 Gs would result in a skull fracture.”
. The 1981 Handbook, or at least copies of portions of the Handbook, was admitted into evidence, but it is nоt part of the record in this appeal. Therefore, the only record references to the contents of the 1981 Handbook are found in Hogan's testimony.
. That chart is not part of the record on appeal; however, a chart which purports to be a copy of the one admitted at trial, is included in Messina's brief.
. In 1991, after the child suffered her injury, the CPSC promulgated some guidelines concerning the accepted depth of various cushioning materials, and this publication was referred to during the course of Hogan's testimony. Like the 1981 Handbook, the 1991 publication is not part of the record on appeal, although Messina has included a chart in his brief which he claims was part of the 1991 CPSC publication.
. Although we have held that warnings by the manufacturer are admissible on the question of standard of care, we have never decided whether such warnings, without more, can serve as the sole basis for the expert’s opinion, and we do not do so now.
See generally Garvey v. O’Donoghue,
. In its brief, the District contends that "the absence of evidence on causation is the most glaring inadequacy in the Messinas’ case.” In short, the District argues that even if the District had violated some national standard concerning cushioning material necessary to prevent skull fractures, Messina has failed to show a violation of that standard caused the child’s broken arm. However, because the District moved for judgment as a matter of law at the close of Hogan's testimony, Messina did not have an opportunity to present his entire case, including medical testimony and the testimony of Mr. Messina. We, therefore, cannot assume that Messina would not have shown causation had he had the opportunity; therefore, we decline to resolve that issue.
